JP2015041620A - Photoelectric conversion element and method for manufacturing photoelectric conversion element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a photoelectric conversion element achieving a high power generation efficiency and power generation output in a wide emitter temperature Te range (400°C≤Te≤2,000°C); and a method for manufacturing a photoelectric conversion element.SOLUTION: A photoelectric conversion element has a light absorption layer including at least one pair of a P type light absorption layer and an N type light absorption layer that are adjacent to each other and relaxed in a lattice mismatch. The light absorption layer has a layer thickness d satisfying 0.5 μm≤d≤5 μm, and a lattice constant (a) at room temperature satisfying 5.886Å≤a≤6.058Å.

Description

  The present invention relates to a photoelectric conversion element used for thermophotovoltaic power generation and a method for manufacturing the photoelectric conversion element.

  Thermophotovoltaic (TPV) power generation is a technology for generating heat by converting thermal radiation light into electricity with a photoelectric conversion element. Usually, in thermophotovoltaic power generation, a ceramic or metal called an emitter is heated, and infrared light emitted from the emitter is converted into electricity. Thermophotovoltaic power generation is attracting attention as a power generation technology with high energy density that can be expected to produce highly efficient power by controlling the radiation spectrum, and can use various heat sources. Non-Patent Document 1 entitled "Application of Thermal Radiation Spectrum Control Technology to Thermophotovoltaic Power Generation" and Non-Patent Document 2 entitled "Current Status of TPV Power Generation System and Selected Emitter Material Technology" Power generation is introduced. The light absorption layer of the photoelectric conversion element for thermophotovoltaic power generation introduced in those documents is made of a material such as Ge, GaSb, InGaAs or the like. These materials have a band gap wavelength of 1.6 μm to 1.8 μm, and absorb light having a shorter band gap wavelength.

  Emitter temperature is limited by emitter material and lifetime. Usually, the temperature of the emitter is 800 to 1200 ° C., and the peak wavelength of the light spectrum emitted from the emitter is as long as 2 to 3 μm. For this reason, in the photoelectric conversion element of the related art, only a part of the radiated light can be converted into current, and the output and efficiency of thermophotovoltaic power generation are limited. The band gap wavelength of the light absorption layer of the photoelectric conversion element is preferably longer than the peak wavelength of the emitted light. When an optical filter is installed between the emitter and the photoelectric conversion element, some wavelength component of the emitted light longer than the band gap wavelength of the light absorption layer of the photoelectric conversion element can be returned to the emitter. However, with such a technique, the efficiency of the photoelectric conversion element is somewhat improved, but the electrical output is not increased.

  In the case of a metal emitter, the emitter temperature is often kept below 1000 ° C. in order to reduce deterioration due to oxidation and extend the lifetime. As the emitter temperature decreases, the peak wavelength of the emitted light increases. Therefore, the power generation efficiency is significantly reduced in the photoelectric conversion element in the related art. In other words, the photoelectric conversion element for photovoltaic power generation in the related art cannot perform high-efficiency and high-power thermophotovoltaic power generation in a wide range of emitter temperatures.

For example, an In _0.53 Ga _0.47 As crystal lattice-matched to an InP substrate is used for an InGaAs light absorption layer of a photoelectric conversion element in related technology. The band gap energy of In _X Ga _1-X As is
Eg (X) = 1.42−1.49 · X + 0.43 · X · X (Formula 1)
And change. The band gap wavelength of In _0.53 Ga _0.47 As lattice-matched to InP is 1.65 μm. Theoretically, the band gap wavelength can be increased from 1.6 μm to 3.4 μm by increasing the In composition x of In _X Ga _1-X As. Then, highly efficient thermophotovoltaic power generation becomes possible over a wider emitter temperature range. Furthermore, conversion efficiency can be further improved by returning to the emitter the wavelength component that the element could not absorb using an optical filter.

However, when the In composition of In _X Ga _1-X As is increased by the conventional epitaxial growth method, the lattice constant of the crystal increases, causing lattice mismatch to the InP crystal as the substrate, resulting in misfit dislocations. Crystal quality will deteriorate. For example, in order to obtain a light absorption layer with an absorption wavelength of 2 μm, the In composition of In _X Ga _1-X As needs to be 0.68 or more. At that time, the degree of lattice mismatch of In _0.68 Ga _0.32 As with respect to InP is 1.0% or more. The degree of lattice mismatch is defined by the ratio Δa / a of the lattice constant difference Δa between the substrate and the epitaxial film and the lattice constant a of the substrate. Usually, since the entire thickness of the light absorption layer is as thick as 0.5 μm or more and 5 μm or less, the deterioration of crystal quality due to lattice mismatch is remarkable.

  From the experiments and theories of critical film thickness, the degree of lattice mismatch for obtaining good crystals with 0.1 μm thick InGaAs is 0.2 to 0.3%. The In composition of the InGaAs crystal at that time is 0.56 to 0.575, and the band gap wavelength of InGaAs at room temperature is 1.72 to 1.75 μm. When the lattice mismatch degree is 0.3%, the In composition of the InGaAs crystal is 0.575, and the lattice constant at room temperature is 5.886 mm. In other words, the long wavelength limit of the InGaAs light absorbing layer pseudo-matched to the InP substrate is 1.75 μm. In other words, in the conventional photoelectric conversion element for photovoltaic power generation, an InGaAs light absorption layer that absorbs light having a wavelength of 1.75 μm or more could not be obtained.

  In recent years, the metamorphic growth method has been used to fabricate some electronic devices. The metamorphic growth method is a crystal growth technique in which the lattice constant is changed while maintaining a good crystal quality of the upper epitaxial layer by using a metamorphic relaxation layer whose lattice constant is gradually changed. When the metamorphic growth method is used, dislocations are formed in a network shape in the metamorphic relaxation layer, and a stable terminal state can be formed, so that the dislocation density in the upper layer can be lowered. If this method is used, a high-quality growth layer may be obtained if the lattice mismatch of the growth layer to the crystal substrate is up to about 3%.

In Non-Patent Document 3, an AlGaInAs relaxation layer is grown on a GaAs substrate using MBE (Molecular Beam Epitaxy) method, and then an InGaAs growth layer that is lattice-matched to InP is grown to realize a transistor element. ing. The AlGaInAs relaxed layer changes the In composition from linear to GaAs to In _0.52 Al _0.48 As.

In Non-Patent Document 4, after growing a metamorphic relaxation layer of In _0.12 Ga _0.88 As on a GaAs substrate by MOVPE (Metal-Organic Vapor Phase Epitaxy) method to a thickness of 1.6 μm, a 1.3 μm band semiconductor A laser is formed. The lattice constant of this InGaAs light emitting layer is slightly larger than that of GaAs and considerably smaller than that of InP.

In Patent Document 1, after a GaSb metamorphic relaxation layer is grown on a GaAs substrate, a photodetector having an undoped In _0.15 Ga _0.85 As _0.14 Sb _0.86 photosensitive layer or an In _0.77 Ga _0.23 As photosensitive layer is formed. . This photodetector has a PIN-type structure in which an undoped photosensitive layer is sandwiched between a P-type hole barrier layer having a band gap larger than that of the photosensitive layer and an N-type electron barrier layer. A reverse bias is applied to the element to receive light in a state where the photosensitive layer is depleted, and photocarriers generated in the photosensitive layer are taken out as a current.

The metamorphic growth method almost always uses a GaAs substrate. The reason is that there is a possibility that an element structure which has been conventionally produced on an expensive InP substrate can be produced on a GaAs substrate having a large diameter with a relatively low cost. However, since there is a lattice mismatch of 3.8% between the GaAs substrate and the InP growth layer, it is not easy to obtain a high quality growth layer. Although it depends on the material and growth conditions, if the degree of lattice mismatch is greater than 4%, three-dimensional growth is likely to occur and it becomes difficult to obtain a flat growth layer. Therefore, it is difficult to grow a material having a larger lattice constant than InP. For example, In _0.68 Ga _0.32 As has a lattice mismatch of 4.9% with respect to the GaAs substrate, so that it is difficult to obtain a flat epitaxial film having a thickness of 100 nm or more.

  Therefore, Patent Document 2 discloses that after forming an InAsP strained superlattice buffer layer on an InP substrate, a GaInAs absorption layer with relaxed lattice mismatch is formed.

  In addition, there is an epitaxial lift-off (ELO) technique in which a growth layer is peeled off from a substrate and transferred to another support. In this technique, a sacrificial layer, which is a layer to be etched, is formed between a substrate and a growth layer, and the sacrificial layer is removed by etching to peel the growth layer from the substrate. The substrate is not etched and can be reused.

In Non-Patent Document 5, an InGaAs relaxation layer (800 nm thickness), InAlAs (100 nm thickness), an AlAs sacrificial layer (4 nm thickness), and an In _0.56 Al _0.44 As barrier layer (1.9 μm layer) with varying In composition on a GaAs substrate. The Hall elements are sequentially stacked. The Hall element portion has a lattice constant close to InP. The In composition of the InGaAs relaxation layer changes in 8 steps from 0.19 to 0.62. However, the AlAs sacrificial layer, which is a lattice mismatching layer, is very thin and takes a very long time to lift off. Therefore, there is a problem that it is difficult to use a large substrate.

  In Patent Document 3, an AlAsSb sacrificial layer lattice-matched to InP and a semiconductor element are formed on an InP substrate, and a semiconductor element thin film lattice-matched to InP is obtained by an ELO method. Such a transfer technique has an advantage that the element can be manufactured at a low cost because the growth substrate can be reused.

  Non-Patent Document 6 reports on the mechanical strength of compound semiconductors.

Applied Physics Vol.73, No.7, P952 (2004) Applied Physics Vol.76, No.3, P281 (2007) W. E. Hoke, J. Vac. Sci. Technol. B 17, 1131 (1999) M. Arai, Electron Lett., Vol. 44, No. 23, pp. 1359-1360 (2008) Y. Jeong, Applied Physics Express 1 (2008) 021201 Yonenaga, “Mechanical Properties and Dislocation Dynamics in III-V Compounds”, Journal De Physique III Vol. 71435-1450 (1997)

JP2012-146806 JP 06-188447 A JP 2008-258563 A

  However, in the photodiode described in Patent Document 3, a transition network existing in the InAsP strained superlattice buffer layer causes many optical carriers to disappear. For this reason, only weak light could be detected. That is, the techniques disclosed in Non-Patent Documents 1 to 6 and Patent Documents 1 to 3 cannot realize a photoelectric conversion element that can obtain high power generation efficiency and power generation output in a wide range of emitter temperatures.

  The objective of this invention is providing the manufacturing method of the photoelectric conversion element which solves the above-mentioned subject, and a photoelectric conversion element.

  The photoelectric conversion device of the present invention has a light absorption layer including at least one pair of P-type light absorption layer and N-type light absorption layer which are adjacent to each other and relaxed by lattice mismatch, and the layer thickness d of the light absorption layer is 0.5 μm. ≦ d ≦ 5 μm, and the lattice constant a of the light absorption layer at room temperature is 5.8865.8 ≦ a ≦ 6.058Å.

The method for producing a photoelectric conversion element of the present invention includes a step of forming a metamorphic relaxation layer on an InP substrate, a step of forming a sacrificial layer on the metamorphic relaxation layer, a P-type light absorption layer and an N on the sacrificial layer. A step of forming a light absorption layer including a mold absorption layer, a step of removing the sacrificial layer by an etching method, and a light absorption layer from which the InP substrate and the metamorphic relaxation layer are peeled off by etching, a transport substrate, a heat sink substrate or And transferring to any one of the laminate substrates.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the photoelectric conversion element which can obtain high power generation efficiency and power generation output in the emitter temperature Te (400 degreeC <= Te <= 2000 degreeC) of wide range can be provided.

1 is a cross-sectional structure diagram of a photoelectric conversion element 100 according to a first embodiment. FIG. 2 is an explanatory diagram of a method for manufacturing the photoelectric conversion element 100 according to the first embodiment. 3 is a cross-sectional structure diagram of a growth layer of the photoelectric conversion element 200 according to the first embodiment. FIG. 1 is a cross-sectional structure diagram of a photoelectric conversion element 200 according to a first embodiment. FIG. 3 is an explanatory diagram of a method for manufacturing the photoelectric conversion element 200 according to the first embodiment. It is explanatory drawing of the 2nd manufacturing method of the photoelectric conversion element 200 concerning a 1st Example. 6 is a cross-sectional structure diagram of a growth layer of a photoelectric conversion element 300 according to a second embodiment. FIG. 3 is a cross-sectional structure diagram of a photoelectric conversion element 300 according to a second embodiment. FIG. 6 is a schematic diagram of a band structure of a photoelectric conversion element 300 according to a second embodiment. FIG. 6 is a cross-sectional structure diagram of a growth layer of a photoelectric conversion element 400 according to a third embodiment. FIG. 6 is a cross-sectional structure diagram of a photoelectric conversion element 400 according to a third embodiment. FIG. FIG. 6 is a schematic diagram of a photoelectric conversion element 400 band structure according to a third embodiment. 6 is a cross-sectional structure diagram of a growth layer of a photoelectric conversion element 500 according to a fourth embodiment. FIG. FIG. 6 is a cross-sectional structure diagram of a photoelectric conversion element 500 according to a fourth embodiment. FIG. 10 is a cross-sectional structure diagram of a growth layer of a photoelectric conversion element 600 according to a fifth embodiment. FIG. 6 is a cross-sectional structure diagram of a photoelectric conversion element 600 according to a fifth embodiment. FIG. 10 is a cross-sectional structure diagram of a growth layer of a photoelectric conversion element 700 according to a sixth embodiment. FIG. 10 is a cross-sectional structure diagram of a photoelectric conversion element 700 according to a sixth embodiment. FIG. 10 is a cross-sectional structure diagram of a growth layer of a photoelectric conversion element 800 according to a seventh embodiment. FIG. 10 is a cross-sectional structure diagram of a photoelectric conversion element according to a seventh embodiment. FIG. 10 is a cross-sectional structure diagram of a growth layer of a photoelectric conversion element 900 according to an eighth embodiment. FIG. 10 is a cross-sectional structure diagram of a photoelectric conversion element 900 according to an eighth embodiment. FIG. 10 is a cross-sectional structure diagram of a growth layer of a photoelectric conversion element 1000 according to a ninth embodiment. FIG. 10 is a cross-sectional structure diagram of a photoelectric conversion element 1000 according to a ninth embodiment. It is a figure which shows the wavelength dependence of the radiation intensity when changing emitter temperature. It is a figure which shows the current-voltage characteristic of the InGaAs type photoelectric conversion element from which a light absorption layer differs. It is a figure which shows the band gap wavelength dependence of the photoelectric conversion efficiency when changing emitter temperature. It is a figure which shows the band gap wavelength dependence of the output density when changing emitter temperature. It is a figure which shows the lattice constant dependence of the conductor of a compound semiconductor, and the energy of a valence band. It is a figure which shows the standard production | generation enthalpy and melting | fusing point of a compound semiconductor. It is a figure which shows the reverse temperature dependence of the critical shear stress of a compound semiconductor. It is a figure which shows the structure of the photoelectric conversion element of patent document 3. FIG.

[First Embodiment]
FIG. 1 is a cross-sectional structure diagram of a photoelectric conversion element 100 according to the first embodiment. The photoelectric conversion element 100 includes at least a pair of adjacent lattice mismatch relaxed P-type light absorption layer 15 and N-type light absorption layer 14 (hereinafter referred to as P-type light absorption layer 15 and N-type light absorption layer 14). And a light absorption layer 19).

The light absorption layer 19 is composed of In _x Ga _1-x As (0.58 ≦ x ≦ 1), In _x Ga _1-x As _y P _1-y (0.58 ≦ x ≦ 1, 0.8 ≦ y <1) or InAs _z P _1-z (0.1 ≦ z ≦ 1) is included.

  The lattice constant a of the light absorption layer 19 at room temperature is 5.8865.8 ≦ a ≦ 6.058Å. Here, 5.886 mm is a value (5.868 × 1.003) considering a critical lattice constant difference of 0.3% with InP. 6.058Å is the lattice constant of InAs at room temperature.

  The layer thickness d of the light absorption layer 19 is 0.5 μm ≦ d ≦ 5 μm. From the viewpoint of shortening the growth time, it is more preferably 1.0 μm or more and 2.5 μm or less. If the light absorption layer is too thin, the incident light cannot be absorbed sufficiently. On the contrary, if the light absorption layer is too thick, the diffusing carriers are recombined in the light absorption layer, and accordingly, the photoelectric conversion efficiency is reduced because it cannot be taken out as current.

  FIG. 2 is an explanatory diagram of a method for manufacturing the photoelectric conversion element 100. For the growth of the epitaxial layer, the MOVPE method or the MBE method is used. First, the metamorphic relaxation layer 12 is formed on the InP substrate 11 (a). Next, a sacrificial layer 13 is formed on the metamorphic relaxation layer 12 (b). Thereafter, an N-type light absorption layer 14 and a P-type light absorption layer 15 are formed in this order on the sacrificial layer 13 (c). Thereafter, the sacrificial layer 13 is etched to peel the metamorphic relaxation layer 12 and the InP substrate 11 from the light absorption layer 19 (d). Note that the P-type light absorption layer 15 and the N-type light absorption layer 14 may be formed in this order on the sacrificial layer 13.

  According to the photoelectric conversion element 100 according to the present embodiment, by forming the metamorphic relaxation layer 12 on the InP substrate, it is possible to obtain a light absorbing layer with a band gap wavelength of 1.8 μm or more with a relaxed lattice mismatch. Further, by peeling the InP substrate 11 and the metamorphic relaxation layer 12 from the light absorption layer 19, the capture of optical carriers in the transition network existing in the metamorphic relaxation layer 12 is eliminated. As a result, conversion efficiency can be improved. Therefore, high power generation efficiency and power generation output can be realized in a wide range of emitter temperatures.

[Example 1]
Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 3 shows a cross-sectional structure diagram of the growth layer of the photoelectric conversion element 200 according to the first embodiment. The growth layer of the photoelectric conversion element 200 is an n-InP substrate 21, an n-In _X Ga _1-X As (0.53 ≦ X ≦ 0.70) metamorphic relaxation layer 22 having a layer thickness of 300 nm, and an n-AlAs _0.44 Sb having a layer thickness of 100 nm. _{A 0.56} sacrificial layer 23, an n-In _0.68 Ga _0.32 As light absorbing layer 24 having a layer thickness of 1.5 μm, and a p-In _0.68 Ga _0.32 As light absorbing layer 25 having a layer thickness of 0.5 μm are included.

  Since InGaAs material is a direct transition material, light absorption efficiency is high. The thickness of the InGaAs light absorption layer can be, for example, 0.5 μm or more and 5 μm or less in order to absorb infrared light. From the viewpoint of shortening the growth time, the thickness of the light absorption layer is preferably 1.0 μm or more and 2.5 μm or less. If the light absorption layer is too thin, the incident light cannot be absorbed sufficiently. If the light absorbing layer is too thick, the efficiency is reduced. This is because the diffusing carriers are recombined in the light absorption layer and cannot be taken out as current.

In addition, In _x Ga _1-x As (0.58 ≦ x ≦ 1) light-absorbing layer, In _x Ga _1-x As _y P _1-y (0.58 ≦ x ≦ 1, 0.8 ≦ y <) relaxed by lattice mismatch. 1) Or lattice mismatch relaxed InAs _z P _1-z (0.1 ≦ z <1) can be used. The lattice constants of these light absorption layers at room temperature are larger than 5.886 mm, which is 1.003 times the critical constant of InP at room temperature (5.868 mm) (critical lattice constant difference: 0.3%), and smaller than the lattice constant of InAs, 6.058 mm.

The metamorphic relaxation layer 22 includes n-In _0.53 Ga _0.47 As 220, n-In _0.58 Ga _0.42 As 221, n-In _0.63 Ga _0.37 As 222, n-In _0.68 Ga _0.32 As 223, n- It comprises 6 layers of In _0.70 Ga _0.30 As 224 and n-In _0.68 Ga _0.32 As 225. For the growth of the epitaxial layer, the MOVPE method or the MBE method is used. The growth temperature is about 600 ° C. to 700 ° C. for the MOVPE method and about 450 ° C. to 650 ° C. for the MBE method. The InP layer having a thickness of 50 nm to be grown at the start of growth is included in the InP substrate 21 in FIG. The metamorphic relaxation layer 22 grows at a growth temperature similar to the normal growth temperature. At the same growth temperature, the mechanical strength of an InGaAs metamorphic relaxation layer with an In composition greater than 0.53 is weaker than the mechanical strength of InP (lower yield point for shear stress), so misfit dislocations are relaxed in InGaAs metamorphic. Confined in a layer.

In this embodiment, the In composition of each layer of the metamorphic relaxation layer 22 is in the range of 0.53 to 0.7, and basically the In composition is increased stepwise by 0.05. However, it may be increased continuously. In the metamorphic relaxation layer 22, when n-In _0.70 Ga _0.30 As 224 having an In composition slightly higher than the In composition of the n-In _0.68 Ga _0.32 As light absorbing layer 24 is grown, the dislocation network is confined in the metamorphic relaxation layer 22 Increases effectiveness.

Si or Se is used for the n-type dopant, and Be, Zn or the like is used for the p-type dopant. Typical doping concentrations are 1 × 10 ¹⁷ cm ^{−3 to} 6 × 10 ¹⁸ cm ⁻³ . Contact resistance can be reduced by locally increasing the doping concentration of the portion in contact with the electrode to about 1 × 10 ¹⁹ cm ⁻³ . The lattice constant of the n-In _0.68 Ga _0.32 As light absorption layer 24 is 5.928Å, and the lattice constant of InP is 5.868Å. By forming the metamorphic relaxation layer 22, the n-In _0.68 Ga _0.32 As light absorption layer 24 has a lattice constant difference of 1.0% relative to InP, but is completely lattice mismatch relaxed.

FIG. 4 shows a cross-sectional structure diagram of the photoelectric conversion element 200. The photoelectric conversion element 200 includes a heat sink 31, a metal layer 32, a P electrode 33, a p-In _0.68 Ga _0.32 As light absorption layer 25, an n-In _0.68 Ga _0.32 As light absorption layer 24, an N electrode 34, and an antireflection film. Comprising 35. As the electrode in contact with the InGaAs layer, Au _0.88 Ge _0.12 (200 nm) Ni (50 nm) / Au (350 nm) is used for the N electrode, and Au _0.8 Zn _0.2 (200 nm) Ni (50 nm) / Au (350 nm) is used for the P electrode. be able to. Alternatively, Ti / Pt / Au may be used for both electrodes.

The antireflection film 35 has a layer structure in which dielectrics having different refractive indexes such as SiO ₂ and Si ₃ N ₄ or SiO ₂ and TiO ₂ are alternately laminated. It is desirable that the antireflection film 35 has a characteristic of transmitting radiated light having a wavelength band of 1 to 2 μm with a high transmittance and reflecting light having a wavelength of 2 μm or more with the highest possible reflectance. The transmittance characteristic T (λ) of the antireflection film 35 is 0 ≦ T (λ ₂ ) <0.5 <T (λ ₁ ) <1 when 1 μm ≦ λ ₁ ≦ λ _g and λ _g ≦ λ ₂ <5 μm. It is desirable to satisfy the following conditions. λ _g is a band gap wavelength.

  As the heat sink 31, an insulator substrate such as an aluminum nitride (AlN) substrate, a sapphire substrate, or a ceramic substrate can be used. In particular, since the aluminum nitride substrate has a thermal expansion coefficient number close to that of an epitaxial layer, it is possible to reduce the stress of the wafer caused by bonding. It is also possible to use a low temperature co-fired ceramic (LTCC) substrate.

  A method for manufacturing the photoelectric conversion element 200 will be described. FIG. 5 is an explanatory diagram of a method for manufacturing the photoelectric conversion element 200. First, the P electrode 33 is formed on the surface of the grown wafer by vacuum deposition. Thereafter, for example, heating is performed in nitrogen at 350 ° C. for 10 minutes to obtain an ohmic junction (FIG. 5 (1)). Next, the P electrode 33 is fusion-bonded to the metal layer 32 formed on the heat sink 31 at about 280 ° C. For example, a fusion material such as AuSn is used as the fusion material. After the heat sink 31 side is protected with wax, the wafer is immersed in an etching solution for several hours, the sacrificial layer 23 is selectively etched, and the InP substrate 21 is removed (lifted off) (FIG. 5B).

As a selective etching solution for the n-AlAs _0.44 Sb _0.56 sacrificial layer 23, HF (hydrogen fluoride) having a concentration of about 40% is used. Alternatively, a hydrofluoric acid solution (HF: H ₂ O ₂ = 1: 1) diluted with water may be used to increase the etching rate. Diluted nitric acid water, hydrochloric acid water, ammonia water, phosphoric acid, etc. can also be used for the diluent. HF and hydrofluoric acid-based solutions can be excellently etched selectively. That is, they etch only the layer containing Sb and do not etch layers such as InGaAs, InP, InAsP, InAlGaAs, and InGaAsP that do not contain Sb. Methyl alcohol or ethylene glycol can also be used for the diluent. When ethylene glycol is used, the etching rate is slow, but etching with high specularity can be performed on the Sb-based compound semiconductor.

  The time required for lift-off depends on the thickness of the sacrificial layer. The etching rate in the horizontal direction parallel to the wafer surface is 8 mm / h when the thickness of the sacrificial layer 23 is 50 nm, and 16 mm / h when the thickness is 100 nm. Therefore, even in the case of a 4-inch InP substrate (diameter 10 cm), it can be lifted off in a practical time of about 3 to 6 hours. Therefore, the layer thickness d2 of the sacrificial layer 23 may be 20 nm ≦ d2 ≦ 200 nm, and more preferably 70 nm ≦ d2 ≦ 120 nm.

  Although hydrofluoric acid is used as the etching solution for the sacrificial layer, any etching solution can be used as long as it is a chemical that can achieve a high etching selectivity between the constituent materials of the sacrificial layer and the epitaxial layer. For example, an etching solution in which ammonia water or phosphoric acid is mixed with hydrofluoric acid can also be used.

  The wafer is bonded to a thin Teflon (registered trademark) carrier, immersed in a hydrofluoric acid-based etching solution while being attached to a jig, and etched while rotating. When a load is applied to the transport substrate, the etchant easily enters the gap to be peeled off, so that the lift-off time can be shortened.

  After removing the wax by organic cleaning, an N electrode 34 is formed on a part of the N-type light absorption layer 24. The wafer is heated at 400 ° C. for about 10 minutes to obtain an ohmic junction of the N electrode 34. Thereafter, an antireflection film 35 is formed on the wafer surface where the N electrode 34 is not formed by CVD or the like. Next, the surface is protected with a resist or the like, and element isolation is performed to a size of about 1 cm square using wet etching or dry etching. Etching is performed until the metal layer 32 connected to the P electrode 33 is exposed.

  When etching an InGaAs epitaxial layer, a phosphoric acid-based etching solution (H3PO4: H2O2: H2O = 3: 1: 500) or the like is used. This can selectively etch InGaAs with respect to InP. In order to selectively etch InGaAs with respect to InAlAs, a citric acid-based etching solution (citric acid: H 2 O 2: H 2 O = 50 g: 50 cc: 50 cc) or the like can be used. In this case, the etching rate of InGaAs in the epi direction at a room temperature is 180 nm / min, the etching rate of InAlAs in the epi direction is 6 nm / min, and the selection ratio is about 30. Alternatively, a higher selectivity can be obtained by a photoetching method in which etching is performed while irradiating light from an excimer lamp. For example, when photoetching is performed by immersing in an HBr solution supplied at 10 sccm at 80 ° C. and 120 torr, the etching rate of InGaAs in the epi direction is 6 nm / min, the etching rate of InAlAs is 0.06 nm / min, and the selection ratio Becomes 100. When performing etching, not only the wafer may be immersed in the solution but also the solution may be sprayed and supplied to the wafer.

After the lift-off is completed, the Au residue on the wafer is removed by etching (etching solution type TFA, manufactured by Transene). In order to reuse the InP substrate, the metamorphic relaxation layer on the InP substrate must be selectively removed. When the metamorphic relaxation layer is InGaAs or InAsP, a phosphoric acid based etching solution is used. H ₃ PO ₄ : HCl (1: 3), H ₂ SO ₄ : H ₂ O ₂ : H ₂ O (1: 1: 10), citric acid: H ₂ O ₂ (20: 1) in that order, and the InGaAs residue Remove. When the metamorphic relaxation layer is AlAsSb or InPSb, a hydrofluoric acid etching solution is used. When a hydrofluoric acid-based etchant diluted with ethylene glycol is used, etching with high specularity can be performed. The newly exposed InP substrate surface was degreased by sequential immersion in heated trichlorethylene, acetone, and heated isopropanol, and an oxide was intentionally generated by exposure to UV / ozone for 10 minutes.

  The photoelectric conversion element 200 can be manufactured not only by the above manufacturing method but also by other methods using lift-off.

  FIG. 6 shows an explanatory diagram of the second manufacturing method of the photoelectric conversion element 200. In the second manufacturing method, the P-type electrode 33, the N-type electrode 34, and the antireflection film 35 are formed on the surface of the epi-wafer, and then the surface is covered with the protective wax 219 and fixed to the transfer substrate 210 (FIG. 6 (1)). ). In this state, the sacrificial layer 23 of the wafer is etched to lift off the InP substrate 21 (FIG. 6B). The lifted surface of the wafer is bonded to the base material 212 with the adhesive 211 (FIG. 6 (2)). After the wafer is heated to melt the protective wax 219 and the transfer substrate 210 is removed, the protective wax 219 on the wafer surface is removed by organic cleaning, whereby a photoelectric conversion element formed on the base 210 is obtained.

  In the above manufacturing method, in the manufacturing process other than lift-off, not only wet etching but dry etching using reactive ions or the like may be used.

The first characteristic of the photoelectric conversion element 200 according to the first embodiment is that the band gap of the n-In _0.68 Ga _0.32 As light absorption layer 24 is 0.61 eV, that is, the band gap wavelength is 2.0 μm. This is suitable when the emitter temperature is relatively high at 1200 ° C. or higher. The second feature is that the same material system as the light absorption layer is used for the metamorphic relaxation layer 22. This reduces the number of necessary materials. The third feature is that the n-AlAs _0.44 Sb _0.56 sacrificial layer 23 is lattice-matched with the n-In _0.68 Ga _0.32 As light absorption layer 24. Therefore, since the thickness of the n-AlAs _0.44 Sb _0.56 sacrificial layer 23 can be increased, the lift-off time can be shortened. As a result, the manufacturing time can be shortened when the size of the substrate is large. A fourth feature is that an unstrained n-In _0.68 Ga _0.32 As light absorption layer 24 having a lattice constant relatively close to that of the InP substrate 21 is used. Thereby, a high-quality light absorption layer can be obtained. The fifth feature is that the InP substrate 21 and the metamorphic relaxation layer 22 are removed from the light absorption layer. Thereby, there is no capture of carriers in the dislocation network, and heat generated in the light absorption layer is easily radiated to the heat sink, thereby improving the photoelectric conversion efficiency. The sixth feature is that since the element structure is simple, there is no energy potential barrier while carriers generated in the light absorption layer diffuse to the electrode. Thereby, a low resistance element is obtained.

  In the following examples, a photoelectric conversion element can be produced by a method similar to the manufacturing method described in the first embodiment and Example 1.

[Example 2]
FIG. 7 is a cross-sectional structure diagram of the growth layer of the photoelectric conversion element 300 according to the second embodiment. The growth layer of the photoelectric conversion element 300 is an n-InP substrate 21, an In _X Ga _1-X As (0 ≦ X ≦ 0.77) metamorphic relaxation layer 42 having a layer thickness of 400 nm, and a p-AlAs _0.38 Sb _0.62 layer having a layer thickness of 100 nm. Layer 43, p-In _0.68 Ga _0.27 Al _0.05 As carrier recombination prevention layer 44 with a layer thickness of 50 nm, p-In _0.75 Ga _0.25 As light absorption layer 45 with a layer thickness of 2 μm, n-In _0.75 Ga _{0.25 with} a layer thickness of 0.6 μm As light absorption layer 46 is included. The undoped In _X Ga _1-X As (0.53 ≦ X ≦ 0.77) metamorphic relaxation layer 42 includes In _0.53 Ga _0.47 As 420, In _0.58 Ga _0.42 As 421, and In _0.63 Ga _0.37 As 422, each having a thickness of 50 nm. In _0.68 Ga _0.32 As 423, In _0.72 Ga _0.28 As 424, In _0.75 Ga _0.25 As 425, In _0.77 Ga _0.23 As 426, and In _0.75 Ga _0.25 As 427.

FIG. 8 shows a cross-sectional structure diagram of the photoelectric conversion element 300 of the second embodiment. The photoelectric conversion element of the second embodiment includes a heat sink 31, a metal layer 32, an N electrode 34, an n-In _0.75 Ga _0.25 As light absorption layer 46, a p-In _0.75 Ga _0.25 As light absorption layer 45, and a p-In _0.68. It includes a Ga _0.27 Al _0.05 As carrier recombination prevention layer 44, a P electrode 33, and an antireflection film 57.

FIG. 9 shows a schematic diagram of a band structure of the photoelectric conversion element 300. An external resistor R is connected to the element so that an optimum forward bias voltage + V 65 is applied during light irradiation. The emitted light 66 that has passed through the antireflection film 57 generates electrons in the conduction band 61 and holes in the valence band 62 mainly in the p-In _0.75 Ga _0.25 As light absorption layer 45 on the surface side. Electrons and holes move in opposite directions by the internal electric field of the PN junction and are absorbed by the N electrode 34 and the P electrode 33, respectively, to generate a photocurrent Iph. Since the photocurrent flows to the external resistor, a forward bias V 65 consumed by the resistor is applied to the element. As a result, the carrier barrier at the PN junction decreases, so that carriers diffuse in the direction over the barrier and reverse saturation current Is (V) flows. Eventually, the total current due to the hole flow 64 is I = Iph−Is (V). The voltage at which the total current becomes zero is called the open circuit voltage Voc, and the current when the external resistance is zero (voltage zero) is called the short-circuit current Isc.

FIG. 29 shows the lattice constant dependence of the compound semiconductor conductor and valence band energy. Comparing the energy difference ΔEc of the conduction band between the p-In _0.75 Ga _0.25 As light absorption layer 45 and the p-In _0.68 Ga _0.27 Al _0.05 As carrier recombination prevention layer 44 and the energy difference ΔEv of the valence band, ΔEc is more It can be seen that it is about 4 times larger. ΔEc is 70 meV to 80 meV. Since holes have small ΔEv, they pass through the p-In _0.68 Ga _0.27 Al _0.05 As carrier recombination prevention layer and are absorbed by the p electrode. On the other hand, electrons generated in the p-In _0.75 Ga _0.25 As light absorption layer 45 move toward the N electrode, but are blocked by the p-In _0.68 Ga _0.27 Al _0.05 As carrier recombination prevention layer 44. Further, since the carrier recombination prevention layer 44 is thin, almost no electrons are present on the surface of the carrier recombination prevention layer 44. For this reason, electrons and holes do not recombine on the surface of the carrier recombination prevention layer 44, so that almost no current loss occurs.

The photoelectric conversion element 300 according to the second embodiment basically has the same characteristics as the photoelectric conversion element 200 according to the first embodiment, but the first characteristic of the photoelectric conversion element 300 is that there is no distortion. The p-In _0.75 Ga _0.25 As light absorption layer 45 has a band gap of 0.54 eV, that is, a band gap wavelength of 2.3 μm. Therefore, according to the photoelectric conversion element 300, higher output and efficiency than the photoelectric conversion element 200 can be obtained. The second feature is that the p-AlAs _0.38 Sb _0.62 sacrificial layer 43 is lattice-matched with the p-In _0.75 Ga _0.25 As light absorption layer 45. Therefore, since the thickness of the p-AlAs _0.38 Sb _0.62 sacrificial layer 43 can be increased, the lift-off time can be shortened. The third feature is that the p-In _0.68 Ga _0.27 Al _0.05 As carrier recombination preventing layer 44 is provided. As a result, the surface recombination of carriers can be prevented without increasing the element resistance, so that the photoelectric conversion efficiency increases.

[Example 3]
FIG. 10 shows a cross-sectional structure diagram of the growth layer of the photoelectric conversion element 400 according to the third embodiment. The growth layer of the photoelectric conversion element 400 includes an InP substrate 71, an InAs _X P _1-X (0 ≦ X ≦ 0.50) metamorphic relaxation layer 72 having a layer thickness of 520 nm, an n-AlAs _0.38 Sb _0.62 sacrificial layer 73 having a layer thickness of 100 nm, Includes n-InAs _0.47 P _0.53 anti-recombination layer 74 with a layer thickness of 50 nm, n-In _0.75 Ga _0.25 As light absorption layer 75 with a layer thickness of 2 μm, and p-In _0.75 Ga _0.25 As light absorption layer 76 with a layer thickness of 0.6 μm It consists of

InAs _X P _1-X (0 ≤ X ≤ 0.50) metamorphic relaxation layer 72 is 50 nm thick InP 720, InAs _0.05 P _0.95 721, InAs _0.10 P _0.90 722, InAs _0.15 P _0.85 723, InAs _0.20 P _0.80 724, InAs _0.25 P _0.85 725, InAs _0.30 P _0.70 726, InAs _0.35 P _0.65 727, InAs _0.40 P _0.60 728, InAs _0.45 P _0.55 729, InAs _0.50 P _0.50 730, InAs _0.47 P _0.53 731. InAs _X P _1-X decreases in mechanical strength as the As composition increases, so misfit dislocations are unlikely to occur in InP. The growth temperature of the InAs _X P _1-X (0 ≦ X ≦ 0.50) metamorphic relaxation layer 72 grows at a temperature about 50 ° C. higher than the growth temperature of the In _0.75 Ga _0.25 As light absorption layer. Since the mechanical strength is lowered by increasing the growth temperature of the metamorphic relaxation layer, the dislocation confinement effect is enhanced.

FIG. 11 shows a cross-sectional structure diagram of the photoelectric conversion element 400. The photoelectric conversion element 400 includes a heat sink 31, a metal layer 32, a P electrode 83, a p-In _0.75 Ga _0.25 As light absorption layer 76, an n-In _0.75 Ga _0.25 As light absorption layer 75, and an n-InAs _0.47 P _0.53 recombination prevention. It includes a layer 74, an N electrode 84, and an antireflection film 87.

FIG. 12 is a schematic diagram of a band structure of the photoelectric conversion element 400. An external resistor R is connected to the element so that an optimum forward bias voltage + V 95 is applied during light irradiation. The radiation 66 transmitted through the antireflection film 87 generates electrons in the conduction band 91 and holes in the valence band 92 mainly in the n-In _0.75 Ga _0.25 As light absorption layer 75 on the surface side. Electrons and holes move in opposite directions by the internal electric field of the PN junction and are absorbed by the N electrode 84 and the P electrode 83, respectively, to generate a photocurrent Iph. Since the photocurrent flows to the external resistor, a forward bias V 65 consumed by the resistor is applied to the element.

Looking at the lattice constant dependence of the energy of the compound semiconductor conductor and valence band in FIG. 29, the conduction bands of the n-In _0.75 Ga _0.25 As light absorption layer 75 and the n-InAs _0.47 P _0.53 recombination prevention layer 74 are shown. Comparing the energy difference ΔEc with the energy difference ΔEv of the valence band, it can be seen that ΔEc is almost zero while ΔEv is large. The ΔEv in the example is 100 meV to 130 meV, which is sufficiently larger than the room temperature thermal energy of 26 meV. Since ΔEc is almost zero, the electron passes through the n-InAs _0.47 P _0.53 recombination preventing layer 74 and is absorbed by the N electrode 84. On the other hand, the holes generated in the n-In _0.75 Ga _0.25 As light absorption layer 75 move toward the P electrode 83, but at the same time, the n-InAs _0.47 P _0.53 recombination prevention layer 74 prevents the hole diffusion to the surface. Be disturbed. Further, since the carrier recombination prevention layer 74 is thin, almost no holes are present on the surface of the carrier recombination prevention layer 74. For this reason, electrons and holes do not recombine on the surface of the carrier recombination prevention layer 74, so that almost no current loss occurs.

The photoelectric conversion element 400 according to the third embodiment basically has the same characteristics as the photoelectric conversion element 300 according to the second embodiment. The first feature of the photoelectric conversion element 400 is that the band gap wavelength of the light absorption layer is 2.3 μm. Therefore, high output and efficiency can be obtained as in the photoelectric conversion element 300. The second characteristic is to have a _{InAs X P 1-X (0} ≦ X ≦ 0.50) metamorphic relieving layer 72. InAs _X P _1-X (0 ≤ X ≤ 0.50) metamorphic relaxation layer 72, comparison is made by increasing the flow rate of AsH ₃ as an As raw material relative to the flow rate of PH ₃ as a P raw material A step structure can be formed easily. The third feature is that the n-InAs _0.47 P _0.53 recombination preventing layer 74 is provided. As a result, even when the light absorption layer on the surface side is n-type, the recombination prevention layer can be formed without increasing the resistance, so that high photoelectric conversion efficiency can be obtained.

[Example 4]
FIG. 13 shows a cross-sectional structure diagram of a growth layer of a photoelectric conversion element 500 according to the fourth embodiment. The growth layer of the photoelectric conversion element 500 is a p-InP substrate 100, p-AlAs _1-X Sb _X (0.44 ≦ X ≦ 0.69) metamorphic relaxation layer 102 with a thickness of 350 nm, p-AlAs _0.33 Sb _{0.67 with} a thickness of 100 nm Layer 103, p-In _0.81 Ga _0.15 Al _0.04 As carrier recombination prevention layer 104 with a layer thickness of 50 nm, unstrained p-In _0.81 Ga _0.19 As light absorption layer 105 with a layer thickness of 2 μm, n-In with a layer thickness of 0.7 μm _{A 0.81} Ga _0.19 As light absorbing layer 106, an n-InAs _0.6 P _0.4 etching stop layer 107 having a layer thickness of 100 nm, and an n-In _0.81 Ga _0.19 As conductive layer 108 having a layer thickness of 2 μm are included. The p doping concentration of the metamorphic relaxation layer 102 is 5 × 10 ¹⁸ cm ⁻³ .

The metamorphic relaxation layer 102 is composed of p-AlAs _0.56 Sb _0.44 1020, p-AlAs _0.51 Sb _0.49 1021, p-AlAs _0.46 Sb _0.54 1022, p-AlAs _0.41 Sb _0.59 1023, p-AlAs _0.36 each having a thickness of 50 nm. Sb _0.64 1024, p-AlAs _0.31 Sb _0.69 1025, p-AlAs _0.33 Sb _0.67 1026. The degree of lattice mismatch with respect to InP of the unstrained p-In _0.81 Ga _0.19 As light absorption layer 105 is 1.9%. The p-AlAs _0.33 Sb _0.67 sacrificial layer 103 and the p-In _0.81 Ga _0.15 Al _0.04 As carrier recombination prevention layer 104 are lattice-matched with the unstrained p-In _0.81 Ga _0.19 As light absorption layer 105.

FIG. 14 shows a cross-sectional structure diagram of the photoelectric conversion element 500. The photoelectric conversion element 500 includes a heat sink 111, an insulating layer 112, an n-In _0.81 Ga _0.19 As conductive layer 108, an n-InAs _0.6 P _0.4 etching stop layer 107, an n-In _0.81 Ga _0.19 As light absorbing layer 106, p. -In _0.81 Ga _0.19 As light absorption layer 105, p-In _0.81 Ga _0.15 Al _0.04 As carrier recombination prevention layer 104, N electrode 113, P electrode 114, and antireflection film 117. The antireflection film 117 is designed to transmit light having a wavelength of 1 to 2.7 μm and reflect light having a wavelength of 2.7 μm or more as much as possible.

The first feature of the photoelectric conversion element 500 according to the fourth embodiment is that the band gap wavelength of the light absorption layer is 2.7 μm. Therefore, the highest power generation output and power generation efficiency can be obtained over a wide temperature range of 800 ° C to 1400 ° C. The second feature is that the growth layer has a p-AlAs _1-X Sb _X (0.44 ≦ X ≦ 0.69) metamorphic relaxation layer 102 having a layer thickness of 350 nm. The p-AlAs _1-X Sb _X layer is grown at a higher temperature than the InP buffer layer. As the growth temperature rises, the p-AlAs _1-X Sb _X layer becomes softer, and the effect of confining the dislocation network in the p-AlAs _1-X Sb _X layer increases. Further, if the metamorphic relaxation layer 102 is doped with a high concentration of p-type, the mechanical strength of the p-AlAs _1-X Sb _X layer decreases. As a result, there is an effect that the quality of the crystal grown on the metamorphic relaxation layer 102 is improved. Further, since the AlAs _1-X Sb _X metamorphic relaxation layer 102 is etched at the time of lift-off similarly to the p-AlAs _0.33 Sb _0.67 sacrificial layer 103, the lift-off time is shortened. The third feature is that since the p-In _0.81 Ga _0.15 Al _0.04 As carrier recombination prevention layer 104 is provided, the photoelectric conversion efficiency can be increased without increasing the resistance. A fourth feature is that there is an n-InAs _0.6 P _0.4 etching stop layer 107. As a result, a photoelectric conversion element having a P electrode and an N electrode on the surface of one side can be manufactured using inexpensive wet etching without the etching stop layer being a barrier for electron flow.

[Example 5]
FIG. 15 shows a cross-sectional structure diagram of a growth layer of a photoelectric conversion element 600 according to the fifth embodiment. The growth layer of the photoelectric conversion element 600 is an n-InP substrate 121, an n-AlAs _1-X Sb _X (0.44 ≦ X ≦ 0.69) metamorphic relaxation layer 122 having a layer thickness of 280 nm, and an n-AlAs _0.33 Sb _{0.67 having} a layer thickness of 80 nm. Sacrificial layer 123, n-InAs _0.6 P _0.4 carrier recombination prevention layer 124 with a layer thickness of 50 nm, n-In _0.81 Ga _0.19 As light absorption layer 125 with a layer thickness of 2 μm, p-In _0.81 Ga _0.19 As light with a layer thickness of 0.7 μm It includes an absorption layer 126, a p-In _0.81 Ga _0.15 Al _0.04 As etching stop layer 127 with a layer thickness of 100 nm, and a p-In _0.81 Ga _0.19 As conductive layer 128 with a layer thickness of 1.5 μm. The n doping concentration of the metamorphic relaxation layer 122 is 5 × 10 ¹⁸ cm ⁻³ . n-AlAs _1-X Sb _X (0.44 ≦ X ≦ 0.69) metamorphic relaxation layer 122 is n-AlAs _0.56 Sb _0.44 1220, n-AlAs _0.51 Sb _0.49 1221, n-AlAs _0.46 Sb _0.54 1222, n-AlAs _0.41 Sb _0.59 1223, n-AlAs _0.36 Sb _0.64 1224, n-AlAs _0.31 Sb _0.69 1225, n-AlAs _0.33 Sb _0.67 1226.

FIG. 16 shows a cross-sectional structure diagram of the photoelectric conversion element 600. The photoelectric conversion element 600 includes a heat sink 111, an insulating layer 112, a p-In _0.81 Ga _0.19 As conductive layer 128, a p-In _0.81 Ga _0.15 Al _0.04 As etching stop layer 127, and an n-In _0.81 Ga _0.19 As light absorption 126. P-In _0.81 Ga _0.19 As light absorption 125, p-In _0.81 Ga _0.15 Al _0.04 As carrier recombination prevention layer 124, N electrode 135, P electrode 138, and antireflection film 137.

A photoelectric conversion element 600 according to the fifth example is a surface PN electrode type photoelectric conversion element having a band gap wavelength of a light absorption layer of 2.7 μm, similar to the photoelectric conversion element 500 according to the fourth example. The light-absorbing layer on the surface side where incident light enters is P-type in the photoelectric conversion element 500, but N-type in the photoelectric conversion element 600. Wherein the photoelectric conversion element 600, by _{p-In 0.81 Ga 0.15 Al 0.04} As the carrier recombination preventing layer, the etch stop layer is used _{p-In 0.81 Ga 0.15 Al 0.04} As which is not the hole of the barrier is there. These layers are lattice matched to relaxed n-In _0.81 Ga _0.19 As light absorption 126. Therefore, the crystal quality is maintained even when these layer thicknesses are changed. In addition, according to the photoelectric conversion element 600, excellent effects similar to those of the photoelectric conversion element 500 can be obtained.

[Example 6]
FIG. 17 is a sectional structural view of a growth layer of a photoelectric conversion element 700 according to the sixth embodiment. The growth layer of the photoelectric conversion element 700 includes an Fe-InP substrate 141, a 400 nm thick InP _1-X Sb _X (0 ≦ X ≦ 0.28) metamorphic relaxation layer 142, a 100 nm thick p-InP _0.74 Sb _0.26 sacrificial layer _{143, p-in 0.92 Ga 0.04} Al 0.04 As carrier recombination prevention layer 144 having a thickness of _{50nm, p-in 0.92 Ga 0.08} As light-absorbing layer 145 having a thickness of 2 [mu] m, the layer thickness 0.6μm n-in _0.92 Ga _0.08 As A light absorbing layer 146 is included.

InP _1-X Sb _X (0 ≦ X ≦ 0.28) Metamorphic relaxation layer 142 has InP 1420, InP _0.95 Sb _0.05 1421, InP _0.90 Sb _0.10 1422, InP _0.85 Sb _0.15 1423, InP _0.80 Sb _0.20 1424, InP _0.75 Sb _0.25 1425, InP _0.72 Sb _0.28 1426, InP _0.74 Sb _0.26 1427. The metamorphic relaxation layer 142 can be formed by gradually increasing the supply flow rate of SbH ₃ or TMSb (trimethylantimony), which is a raw material of Sb, stepwise with respect to PH ₃ supplied during growth. The metamorphic relaxation layer 142 may be p-type doped.

FIG. 18 is a cross-sectional structure diagram of the photoelectric conversion element 700. The photoelectric conversion element 700 includes a polymer film 151 having a thickness of 50 μm to 100 μm, a metal film 152 having a thickness of 50 μm, an alloy layer 153, an N electrode 154, a P electrode 155, an n-In _0.92 Ga _0.08 As light absorption layer 146, p -In _0.92 Ga _0.08 As light absorption layer 145, p-In _0.92 Ga _0.04 Al _0.04 As carrier recombination prevention layer 144, and antireflection film 157.

  The antireflection film 157 is designed to transmit light of 1 to 3 μm and reflect light of 3 μm or more as much as possible. The polymer film 151 is pressure-bonded (laminated) with a metal film 152. For the metal film 152, materials such as aluminum, copper, and stainless steel can be used. For the polymer film 151, polyamide, polyimide, polyethersulfone, polyester, acrylic butadiene styrene, or the like, which is a high heat resistant polymer material, can be applied. Alternatively, polycarbonate, polymethyl methacrylate, polyethylene naphthalate, and polyethylene terephthalate, which are highly transparent polymer materials, can also be applied. Since the laminate film substrate is flexible, it can be attached to the inner wall of an aluminum heat sink having an inner wall on a cylinder, for example. By installing the emitter in the center of the cylinder, the photoelectric conversion element attached to the inner wall on the cylinder can be irradiated without leaking the radiation light radiated radially.

The first feature of the photoelectric conversion element 700 according to the sixth embodiment is that a light absorption layer having a band gap wavelength of 3.0 μm is used. Thus, when the emitter temperature is relatively low, 800 ° C. to 1000 ° C., the maximum output and efficiency of the photoelectric conversion element can be realized. The second feature is that the InP _1-X Sb _X (0 ≦ X ≦ 0.28) metamorphic relaxation layer 142 is used. As a result, a high-quality n-In _0.92 Ga _0.08 As light absorption layer 146 is obtained. Further, since the metamorphic relaxation layer 142 is etched together with the p-InP _0.74 Sb _0.26 sacrificial layer 143 at the time of lift-off, the lift-off time is shortened. The third feature is that a laminated film substrate is used. As a result, the photoelectric conversion element can be arranged in a curved shape so as to surround the emitter, so that the radiated light can be received efficiently. Moreover, since the film base is light, the power generation device is reduced in weight.

The second feature will be described in detail. When the In composition of InGaAs is large, it is better to use InP _1-X Sb _X for the metamorphic relaxation layer than to use AlAs _1-X Sb _X for higher quality n-In _0.92 Ga _0.08 As light absorption layer 146 is obtained.

  FIG. 30 shows the standard generation enthalpy and melting point of a compound semiconductor. The standard enthalpy of formation and the melting point are approximately proportional. This is because the standard formation enthalpy and melting point increase as the crystal becomes harder. As can be seen from FIG. 30, the melting point of InGaAs used in the present invention is 950 ° C. to 1100 ° C., the melting point of InPSb is 850 ° C. to 1000 ° C., and the melting point of AlAsSb is 1250 ° C. to 1350 ° C. That is, the melting point decreases in the order of AlAsSb, InGaAs, and InPSb. Since dislocation occurs in a layer with low crystal strength, InPSb with low crystal strength has a high effect of confining the dislocation network.

FIG. 31 shows the inverse temperature dependence of the critical shear stress of a compound semiconductor. Critical shear stress represents the mechanical strength of a material. The higher the temperature, the lower the critical shear stress. Since the epilayer is at the same temperature during growth, the critical shear stress is compared at the same temperature. InPSb or InPAs used in the metamorphic relaxation layer of the present invention has the same mechanical strength as In ⁺ GaAs having an In composition greater than 0.58 used in the present invention. On the other hand, AlAsSb has higher mechanical strength than In ⁺ GaAs. Therefore, since InPSb or InPAs has a lower mechanical strength than AlAsSb, the effect of confining the dislocation network in InP _1-X Sb _X or InP _1-X As _X is great. In ^- GaAs growth on a GaAs substrate in the related technology did not become a significant problem, but in In ⁺ GaAs growth on the InP substrate of the present invention, in order to obtain a high-quality light absorption layer, a metamorphic layer was used. It is necessary to use InPSb or InPAs.

[Example 7]
FIG. 19 is a cross-sectional structure diagram of the growth layer of the photoelectric conversion element 800 according to the seventh embodiment. The growth layer of the photoelectric conversion element 800 includes an Fe-InP substrate 161, a 400 nm thick InP _1-X Sb _X (0 ≦ X ≦ 0.28) metamorphic relaxation layer 162, and a 100 nm thick n-InP _0.74 Sb _0.26 sacrificial layer. 163, n-InAs _0.83 P _0.17 carrier recombination prevention layer 164 with a layer thickness of 50 nm, relaxed n-In _0.92 Ga _0.08 As light absorption layer 165 with a layer thickness of 2 μm, p-In _0.92 Ga _0.08 As light with a layer thickness of 0.6 μm An absorbent layer 166 is included. InP _1-X Sb _X (0 ≦ X ≦ 0.28) Metamorphic relaxation layer 162 has InP 1620, InP _0.95 Sb _0.05 1621, InP _0.90 Sb _0.10 1622, InP _0.85 Sb _0.15 1623, InP _0.80 Sb, each having a thickness of 50 nm. _0.20 1624, InP _0.75 Sb _0.25 1625, InP _0.72 Sb _0.28 1626, InP _0.74 Sb _0.26 1627. The metamorphic relaxation layer 162 may be subjected to n-type doping.

FIG. 20 shows a cross-sectional structure diagram of the photoelectric conversion element 800. The photoelectric conversion element 800 includes a polymer film 151 having a thickness of 50 μm to 100 μm, a metal film 152 having a thickness of 50 μm, an alloy layer 153, an N electrode 174, a P electrode 175, a p-In _0.92 Ga _0.08 As light absorption layer 166, n -In _0.92 Ga _0.08 As light absorption layer 165, n-InAs _0.83 P _0.17 carrier recombination prevention layer 164, and antireflection film 177. The antireflection film 177 is designed to transmit light having a wavelength of 1 to 3 μm and reflect light having a wavelength of 3 μm or more as much as possible.

In the photoelectric conversion element 800 according to the seventh example, the band gap wavelength of the light absorption layer is 3.0 μm, like the photoelectric conversion element 700 according to the sixth example. In the photoelectric conversion element 700, the light absorption layer on the emission surface side is P-type, whereas in the photoelectric conversion element 800, the light absorption layer on the emission surface side is N-type. Further, in the photoelectric conversion element 700, the carrier recombination prevention layer is p-In _0.92 Ga _0.04 Al _0.04 As, whereas in the photoelectric conversion element 800, the carrier recombination prevention layer is n-InAs _0.83 P _0.17. Different.

[Example 8]
FIG. 21 is a cross-sectional structure diagram of the growth layer of the photoelectric conversion element 900 according to the eighth embodiment. The growth layer of the photoelectric conversion element 900 includes an InP substrate 181, an InP _1-X Sb _X (0 ≦ X ≦ 0.35) metamorphic relaxation layer 182 having a layer thickness of 450 nm, an n-InP _0.68 Sb _0.32 sacrificial layer 183 having a layer thickness of 100 nm, It includes an n-InAs _0.90 P _0.10 strain carrier recombination preventing layer 184 having a layer thickness of 10 nm, an n-InAs light absorption layer 185 having a layer thickness of 2 μm, and a p-InAs light absorption layer 186 having a layer thickness of 0.5 μm. InP _1-X Sb _X (0 ≦ X ≦ 0.35) metamorphic relaxation layer 182 is 50 nm thick InP 1820, InP _0.95 Sb _0.05 1821, InP _0.90 Sb _0.10 1822, InP _0.85 Sb _0.15 1823, InP _0.80 Sb _0.20 1824, InP _0.75 Sb _0.25 1825, InP _0.70 Sb _0.30 1826, InP _0.65 Sb _0.35 1827, InP _0.68 Sb _0.32 1828. In order to realize a high-quality InAs light absorption layer, it is preferable to use the InP _1-X Sb _X (0 ≦ X ≦ 0.35) metamorphic relaxation layer 182. The metamorphic relaxation layer 182 may be n-doped.

FIG. 22 shows a cross-sectional structure diagram of the photoelectric conversion element 900. Photoelectric conversion element 900, polymer film 151 having a thickness of 50 μm to 100 μm, metal film 152 having a thickness of 50 μm, alloy layer 153, P electrode 194, N electrode 195, p-InAs light absorption layer 186, n-InAs light absorption layer 185, an n-InAs _0.90 P _0.10 strain carrier recombination preventing layer 184, and an antireflection film 197. The antireflection film 197 is designed to transmit light having a wavelength of 1.4 to 3.4 μm and reflect light having a wavelength of 3.4 μm or more as much as possible.

  In the photoelectric conversion element 900 according to the eighth embodiment, the band gap wavelength of the InAs light absorption layer is 3.4 μm. Thereby, it is possible to realize a thin film photoelectric conversion element capable of obtaining a high output and efficiency with respect to a low emitter temperature of about 800 ° C.

[Example 9]
FIG. 23 is a cross-sectional structure diagram of the growth layer of the photoelectric conversion element 1000 according to the ninth embodiment of the present invention. The growth layer of the photoelectric conversion element 1000 includes an InP substrate 220, an InP _1-X Sb _X (0 ≦ X ≦ 0.30) metamorphic relaxation layer 221, an n-InP _0.75 Sb _0.25 sacrificial layer 223, and an n-InAs _0.90 P _0.10 light absorption. The layer 224 includes a p-InGaAsP light absorption layer 225. The InP _1-X Sb _X (0 ≦ X ≦ 0.30) metamorphic relaxation layer 221 includes nine layers, each having a thickness of 50 nm. In the metamorphic relaxation layer 221, the Sb composition increases to 0.30 in 0.05 steps and finally returns to 0.25. The n-InP _0.75 Sb _0.25 sacrificial layer 223, the n-InAs _0.90 P _0.10 light absorption layer 224, and the p-InGaAsP light absorption layer 225 are lattice-matched to each other. The room temperature band gap wavelength of the n-InAs _0.90 P _0.10 light absorption layer 224 is 2.2 μm.

FIG. 24 shows a cross-sectional structure diagram of the photoelectric conversion element 1000. The photoelectric conversion element 1000 includes a polymer film 151, a metal film 152, an alloy layer 153, a P electrode 194, a p-InGaAsP light absorption layer 225, an n-InAs _0.90 P _0.10 light absorption layer 224, an N electrode 195, and an antireflection film 227. Comprising. The antireflection film 227 is designed to transmit light having a wavelength of 1 μm to 2.2 μm and reflect light having a wavelength of 2.2 μm or more as much as possible.

The first feature of the photoelectric conversion element 1000 according to the ninth embodiment is that the band gap wavelength of the main light absorption layer is 2.2 μm. This absorption wavelength provides high power and efficiency over a wide range of emitter temperatures. The second feature is that In _x Ga _1-x As _y P _1-y (0.58 ≦ x ≦ 1, 0.8 ≦ y <1) mixed crystal or InAs _z P _1-z (0.1 ≦ z ≦ 1) ) Mixed crystals are used. That is, a compound semiconductor material containing no Sb other than InGaAs can be used for the light absorption layer of the photoelectric conversion element.
[Effect of the invention]
The effects of the present invention will be described using experimental results of the photoelectric conversion element 2000 created by the same method as in the first embodiment and Examples 1 to 9. In the photoelectric conversion element 2000, an In _0.80 Ga _0.20 As light absorption layer was used as the light absorption layer. For comparison, a photoelectric conversion element 3000 described in Patent Document 3 was manufactured. FIG. 32 shows a structure of the photoelectric conversion element 3000 and a manufacturing method thereof. First, an AlAs _0.56 Sb _0.44 sacrificial layer 2 that is lattice-matched with the substrate is formed on the InP substrate 1 by an epitaxial growth technique. Next, an n-type InP layer 3, an n-type In _0.53 Ga _0.47 As layer 4, and a p-type In _0.53 Ga _0.47 As layer 5 are sequentially stacked on the sacrificial layer 2. Thereafter, although not shown, each layer is processed to form a photodiode (PD). Next, after forming an insulating film covering the PD, an electrode connected to each element of the PD is formed. On the other hand, a support substrate on which electrodes corresponding to PD electrodes are formed is prepared. Then, the support substrate is bonded or bonded to the substrate side so that the electrodes of the PD and the electrodes formed on the support substrate are bonded to each other. Thereafter, the sacrificial layer 2 is removed by etching, and the substrate 1 is peeled off from the n-type InP layer 3. In Patent Document 3, an InGaAs-based PD element lattice-matched to InP is formed, and a PD element thin film is formed by the ELO method. Unlike the solar cell, the obtained PD element receives light with a reverse bias applied.

FIG. 25 shows the wavelength dependence of the radiation intensity when the emitter temperature is changed. The emitter radiation characteristics are approximated by blackbody radiation. In FIG. 25, the band gap wavelength of 1.65 μm of In _0.53 Ga _0.47 As used in the photoelectric conversion element 3000 and the band gap wavelength of 2.7 μm of In _0.80 Ga _0.20 As used in the photoelectric conversion element 2000 are shown simultaneously. . The peak wavelengths of the emission spectra for the emitter temperatures of 1400 ° C., 1200 ° C., 1000 ° C., and 800 ° C. are 1.7 μm, 2.0 μm, 2.3 μm, and 2.8 μm, respectively. As the emitter temperature decreases, the radiation intensity decreases and the peak wavelength of the emission spectrum increases. The InGaAs light absorption layer absorbs radiation having a wavelength shorter than the band gap wavelength. It can be seen that the photoelectric conversion element 2000 has a larger radiation spectrum area than the photoelectric conversion element 3000 can absorb. When the emitter temperature is 1000 ° C. or less, the area of the radiation spectrum that can be absorbed at the band gap wavelength of the photoelectric conversion element 3000 becomes extremely small.

FIG. 26 shows current-voltage characteristics of InGaAs photoelectric conversion elements having different light absorption layers. As a light absorption layer, an element using In _0.53 Ga _0.47 As according to Patent Document 3 (In _0.53 Ga _0.47 As element) and an element using In _0.80 Ga _0.20 As according to the present invention (In _0.80 Ga _0.20 As element) are used. The current-voltage characteristics at a typical emitter temperature of 1200 ° C. were measured at room temperature. The light intensity received by the element was obtained by estimating and correcting the light intensity transmitted through the antireflection film.

The open circuit voltage of the In _0.53 Ga _0.47 As element was 0.51 (V), the short-circuit current density was 4.2 (A / cm ² ), the filling factor was 80%, and the output density was 1.75 (W / cm ² ). On the other hand, the open-circuit voltage of the In _0.80 Ga _0.20 As element was 0.26 (V), the short-circuit current density was 19.6 (A / cm ² ), the filling factor was 70%, and the output density was 3.52 (W / cm ² ). Even in the In _0.80 Ga _0.20 As device, an InGaAs photoelectric conversion device having a crystal quality equivalent to that of a lattice-matched crystal was obtained. In the In _0.80 Ga _0.20 As device, the high crystal quality InGaAs layer was obtained because an InP substrate having a smaller lattice mismatch between the substrate and the growth layer was used. In the high crystal quality InGaAs layer, since the carrier diffusion length is as large as several tens of μm compared to the low quality, the reverse saturation current value is reduced by an order of magnitude, and the open-circuit voltage Voc is increased by 0.1 V or more. Output is improved.

Compared with the In _0.53 Ga _0.47 As element, the In _0.80 Ga _0.20 As element has a small band gap, so the open-circuit voltage is halved, but the short-circuit current density is quadrupled. As a result, the power density doubled. As a result, at a typical emitter temperature of 1200 ° C., the InGaAs-based photoelectric conversion element according to the present invention provided an output twice that of the photoelectric conversion element according to Patent Document 3.

  FIG. 27 shows the bandgap wavelength dependence of the photoelectric conversion efficiency when the emitter temperature is changed. The photoelectric conversion efficiency was defined by the output density from the device with respect to the radiant energy density of all wavelengths of the emitted light from the emitter. A curve represents a value calculated from device characteristics. The black circle is the experimental value when the emitter temperature is 1200 ° C, and the white circle is the experimental value when the emitter temperature is 800 ° C.

The peak band gap wavelengths of the efficiency for the emitter temperatures of 1400 ° C., 1200 ° C., 1000 ° C., and 800 ° C. are 2.6 μm, 2.7 μm, 3.0 μm, and 3.2 μm, respectively. The optimum bandgap wavelength depends on the emitter temperature. As the emitter temperature decreases, the peak bandgap wavelength of efficiency increases. At an emitter temperature of 800 ° C. to 1400 ° C., a suitable band gap wavelength was 2.0 μm to 3.4 μm, and a more suitable band gap wavelength was 2.5 μm to 3.2 μm. At an emitter temperature of 1200 ° C., the efficiency of the In _0.53 Ga _0.47 As element was 6.5%, and the efficiency of the In _0.80 Ga _0.20 As element was 13.2%. At an emitter temperature of 800 ° C., the efficiency of the In _0.53 Ga _0.47 As element was 1.4%, and the efficiency of the In _0.80 Ga _0.20 As element was 5.9%. With the element structure according to the present invention, an effect of increasing the photoelectric conversion efficiency by 2 to 4 times was obtained.

  The peak wavelength of efficiency at an emitter temperature of 400 ° C. is 3.2 μm. According to the element structure of the eighth embodiment, high conversion efficiency can be obtained even at an emitter temperature of 400 ° C. The peak wavelength of efficiency at an emitter temperature of 2000 ° C. is 2.3 μm. According to the element structure of the first embodiment, high conversion efficiency can be obtained even at an emitter temperature of 2000 ° C. Accordingly, in a thermophotovoltaic power generation apparatus including a high-temperature emitter and a photoelectric conversion element, according to the present invention, a photoelectric conversion element that realizes the maximum power generation efficiency in a wide range of emitter temperatures Te (400 ° C. ≦ Te ≦ 2000 ° C.) is provided. can do.

  FIG. 28 shows the band gap wavelength dependence of the output density when the emitter temperature is changed. A curve represents a value calculated from device characteristics. The black circle is the experimental value when the emitter temperature is 1200 ° C, and the white circle is the experimental value when the emitter temperature is 800 ° C.

The output peak band gap wavelengths for emitter temperatures of 1400 ° C, 1200 ° C, 1000 ° C, and 800 ° C are 2.6 μm, 2.7 μm, 3.0 μm, and 3.2 μm, respectively, which are almost the same as the peak bandgap wavelength of efficiency. . At an emitter temperature of 1200 ° C., the efficiency of the In _0.53 Ga _0.47 As element was 1.75 (W / cm ² ), and the efficiency of the In _0.80 Ga _0.20 As element was 3.52 (W / cm ² ). At an emitter temperature of 800 ° C., the efficiency of the In _0.53 Ga _0.47 As element was 0.11 (W / cm ² ), and the efficiency of the In _0.80 Ga _0.20 As element was 0.44 (W / cm ² ). With the element structure according to the present invention, an effect of increasing the output density after photoelectric conversion by 2 to 4 times was obtained. In particular, at a low emitter temperature, the device structure according to the present invention provided four times the efficiency and output of the photoelectric conversion device according to Patent Document 3.

  The peak wavelength of output at an emitter temperature of 400 ° C. is 3.2 μm. According to the element structure of the eighth embodiment, the maximum output can be obtained even at an emitter temperature of 400 ° C. The peak wavelength of the output at an emitter temperature of 2000 ° C. is 2.2 μm, and the maximum output can be obtained even at an emitter temperature of 2000 ° C. by the element structure of the first embodiment. Therefore, in a thermophotovoltaic power generation apparatus including a high temperature emitter and a photoelectric conversion element, according to the present invention, a photoelectric conversion element that realizes the maximum power generation output in a wide range of emitter temperatures Te (400 ° C. ≦ Te ≦ 2000 ° C.) is provided. can do.

  The doped InP substrate absorbs the infrared light component from the emitter, thereby increasing the element temperature and reducing the power generation efficiency. According to the element structure of the present invention, a photoelectric conversion element excellent in heat dissipation can be obtained by removing the InP substrate. In the present invention, since the metamorphic relaxation layer is removed, current loss due to the dislocation network existing in the relaxation layer does not occur. Moreover, in the manufacturing method according to the present invention, since the InP substrate after lift-off can be reused, the manufacturing cost of the element can be reduced. Various materials such as a flexible polymer base material can be selected for the substrate to be transferred. By disposing the photoelectric conversion element so as to surround the emitter, the area of the element that receives the emitted light from the emitter can be increased. Further, by selecting an ideal configuration for the antireflection film or the multilayer filter disposed between the photoelectric conversion element and the emitter, it is possible to realize thermoelectric power generation with higher efficiency and higher output.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, It cannot be overemphasized that another modification and an application example are included unless it deviates from the meaning of this invention.

  Part or all of the above embodiments can be described as follows, but is not limited to the following.

(Appendix 1)
A light absorption layer comprising at least a pair of adjacent lattice mismatch relaxed P-type light absorption layer and N-type light absorption layer;
The thickness d of the light absorbing layer is 0.5 μm ≦ d ≦ 5 μm,
The photoelectric conversion element, wherein the light absorption layer has a lattice constant a at room temperature of 5.886Å ≦ a ≦ 6.058Å.

(Appendix 2)
The light absorption layer is made of In _x Ga _1-x As (0.58 ≦ x ≦ 1), In _x Ga _1-x As _y P _1-y (0.58 ≦ x ≦ 1, 0.8 ≦ y <1) or InAs _z P _The photoelectric conversion element according to appendix 1, including any one of _1-z (0.1 ≦ z ≦ 1).

(Appendix 3)
A P-type In _x Ga _1-xw Al _w As (0.58 ≦ x ≦ 1, 0.02 ≦ w ≦ 0.2) layer lattice-matched with the P _- type light absorption layer is formed adjacent to the P-type light absorption layer, or The photoelectric according to appendix 1 or 2, wherein an N-type InAs _u P _1-u (0.1 ≦ u ≦ 0.9) layer lattice-matched to the N _- type light absorption layer is formed adjacent to the N-type light absorption layer. Conversion element.

(Appendix 4)
Further comprising an antireflection film made of a dielectric provided on the light absorption layer,
The transmittance characteristic T (λ) of the antireflection film is 0 ≦ T (λ ₂ ) <0.5 <T (λ ₁ ) <1 and 1 μm ≦ λ with respect to the band gap wavelength λ _g (μm) of the light absorption layer. _The photoelectric conversion element according to any one of appendices 1 to 3, wherein the conditions of ₁ ≦ λ _g and λ _g ≦ λ ₂ <5 μm are satisfied.

(Appendix 5)
Forming a metamorphic relaxation layer on the InP substrate;
Forming a sacrificial layer on the metamorphic relaxation layer;
Forming a light absorption layer including a P-type light absorption layer and an N-type absorption layer on the sacrificial layer;
Removing the sacrificial layer by an etching method;
Transferring the light absorbing layer from which the InP substrate and the metamorphic relaxation layer have been peeled off by the etching to any one of a transport base, a heat sink base, and a laminate base. A method for manufacturing a conversion element.

(Appendix 6)
The method for producing a photoelectric conversion element according to appendix 5, wherein at least a part of the lattice constant in the metamorphic relaxation layer increases stepwise or continuously from the lattice constant of InP to the lattice constant of the light absorption layer.

(Appendix 7)
The metamorphic relaxation layer is made of In _X Ga _1-X As (0.53 ≦ x ≦ 1), InAs _y P _1-y (0 ≦ y ≦ 1), AlAs _1-X Sb _X (0.44 ≦ x ≦ 0.84) or The method for producing a photoelectric conversion element according to appendix 5 or 6, including at least one of InP _1-y Sb _y (0 ≦ y ≦ 0.32).

(Appendix 8)
The method for manufacturing a photoelectric conversion element according to any one of appendices 5 to 7, wherein the sacrificial layer is lattice-matched to the light absorption layer.

(Appendix 9)
The method of manufacturing a photoelectric conversion element according to any one of appendices 5 to 8, wherein a layer thickness d2 of the sacrificial layer is 20 nm ≦ d2 ≦ 200 nm.

(Appendix 10)
The sacrificial layer includes any one of AlAs _1-X Sb _X (0.48 ≦ x ≦ 0.84) and InP _1-y Sb _y (0.05 ≦ y ≦ 0.32), according to any one of appendices 5 to 9. The manufacturing method of the photoelectric conversion element of description.

(Appendix 11)
An InP substrate,
A metamorphic relaxation layer formed on the InP substrate;
A sacrificial layer formed on the metamorphic relaxation layer;
A light absorption layer formed on the sacrificial layer,
The semiconductor device according to claim 1, wherein the light absorption layer includes a P-type InGaAs layer and an N-type InGaAs light absorption layer.

1, 11, 21, 71, 100, 121, 141, 161, 181, 220 InP substrate
33, 83, 114, 138, 155, 175, 194 P electrode
34, 84, 113, 135, 154, 174, 195 N electrode
35, 57, 87, 117, 137, 157, 177, 197, 217, 227 Antireflection film
2 AlAs _0.56 Sb _0.44 sacrificial layer
3 n-type InP layer
4 n-type In _0.53 Ga _0.47 As layer
5 p-type In _0.53 Ga _0.47 As layer
12 Metamorphic relaxation layer
13 Sacrificial layer
14 N-type absorber layer
15 P-type light absorption layer
16 emitter
19 Light absorption layer
22 n-In _X Ga _1-X As (0.53 ≦ X ≦ 0.70) metamorphic relaxation layer
23 n-AlAs _0.44 Sb _0.56 sacrificial layer
24 n-In _0.68 Ga _0.32 As light absorption layer
25 p-In _0.68 Ga _0.32 As light absorption layer
220 n-In _0.53 Ga _0.47 As
221 n-In _0.58 Ga _0.42 As
222 n-In _0.63 Ga _0.37 As
223 n-In _0.68 Ga _0.32 As
224 n-In _0.70 Ga _0.30 As
225 n-In _0.68 Ga _0.32 As
31 Heat sink
32 metal layers
203 Sacrificial layer
219 Protective wax
210 Transfer board
212 Substrate
211 Adhesive
42 In _X Ga _1-X As (053 ≦ X ≦ 0.77) metamorphic relaxation layer
43 p-AlAs _0.38 Sb _0.62 sacrificial layer
44 p-In _0.68 Ga _0.27 Al _0.05 As Carrier recombination prevention layer
45 p-In _0.75 Ga _0.25 As light absorption layer
46 n-In _0.75 Ga _0.25 As light absorption layer with a layer thickness of 0.6μm
420 In _0.53 Ga _0.47 As
421 In _0.58 Ga _0.42 As
422 In _0.63 Ga _0.37 As
423 In _0.68 Ga _0.32 As
424 In _0.72 Ga _0.28 As
425 In _0.75 Ga _0.25 As
426 In _0.77 Ga _0.23 As
427 In _0.75 Ga _0.25 As
46 n-In _0.75 Ga _0.25 As light absorption layer
45 p-In _0.75 Ga _0.25 As light absorption layer
44 p-In _0.68 Ga _0.27 Al _0.05 As Carrier recombination prevention layer
72 InAs _X P _1-X (0 ≦ X ≦ 0.50) metamorphic relaxation layer
73 n-AlAs _0.38 Sb _0.62 sacrificial layer
74 n-InAs _0.47 P _0.53 Anti-recombination layer
75 n-In _0.75 Ga _0.25 As light absorption layer
76 p-In _0.75 Ga _0.25 As light absorption layer
721 InAs _0.05 P _0.95
722 InAs _0.10 P _0.90
723 InAs _0.15 P _0.85
724 InAs _0.20 P _0.80
725 InAs _0.25 P _0.85
726 InAs _0.30 P _0.70
727 InAs _0.35 P _0.65
728 InAs _0.40 P _0.60
729 InAs _0.45 P _0.55
730 InAs _0.50 P _0.50
731 InAs _0.47 P _0.53
95 Forward bias voltage + V
66 Synchrotron radiation
91 conduction band
92 Valence band
102 AlAs _1-X Sb _X (0.44 ≦ X ≦ 0.69) metamorphic relaxation layer
103 p-AlAs _0.33 Sb _0.67 sacrificial layer
104 p-In _0.81 Ga _0.15 Al _0.04 As carrier recombination prevention layer
105 p-In _0.81 Ga _0.19 As light absorption layer
106 n-In _0.81 Ga _0.19 As light absorption layer
107 n-InAs _0.6 P _0.4 Etching stop layer
108 n-In _0.81 Ga _0.19 As conductive layer
1020, 1220 AlAs _0.56 Sb _0.44
1021, 1221 AlAs _0.51 Sb _0.49
1022, 1222 AlAs _0.46 Sb _0.54
1023, 1223 AlAs _0.41 Sb _0.59
1024, 1224 AlAs _0.36 Sb _0.64
1025, 1225 AlAs _0.31 Sb _0.69
1026, 1226 AlAs _0.33 Sb _0.67
111 heat sink
112 Insulation layer
122 AlAs _1-X Sb _X (0.44 ≦ X ≦ 0.69) metamorphic relaxation layer
123 n-AlAs _0.33 Sb _0.67 sacrificial layer
124 n-InAs _0.6 P _0.4 Carrier recombination prevention layer
125 n-In _0.81 Ga _0.19 As light absorption layer
126 p-In _0.81 Ga _0.19 As light absorption layer
127 p-In _0.81 Ga _0.15 Al _0.04 As etch stop layer
128 p-In _0.81 Ga _0.19 As conductive layer
142 InP _1-X Sb _X (0 ≦ X ≦ 0.28) metamorphic relaxation layer
143 p-InP _0.74 Sb _0.26 sacrificial layer
144 p-In _0.92 Ga _0.04 Al _0.04 As Carrier recombination prevention layer
145 p-In _0.92 Ga _0.08 As light absorption layer
146 n-In _0.92 Ga _0.08 As light absorption layer
151 polymer film
152 Metal film
153 Alloy layer
162 InP _1-X Sb _X (0 ≦ X ≦ 0.28) metamorphic relaxation layer
163 n-InP _0.74 Sb _0.26 sacrificial layer
164 n-InAs _0.83 P _0.17 Carrier recombination prevention layer
165 n-In _0.92 Ga _0.08 As light absorption layer
166 p-In _0.92 Ga _0.08 As light absorption layer
720, 1420, 1620, 1820 InP
1421, 1621, 1821 InP _0.95 Sb _0.05
1422, 1622, 1822 InP _0.90 Sb _0.10
1423, 1623, 1823 InP _0.85 Sb _0.15
1424, 1624, 1824 InP _0.80 Sb _0.20
1425, 1625, 1825 InP _0.75 Sb _0.25
1426, 1626, 1826 InP _0.72 Sb _0.28
1427, 1627, 1827 InP _0.74 Sb _0.26
182 InP _1-X Sb _X (0 ≦ X ≦ 0.35) metamorphic relaxation layer
183 n-InP _0.68 Sb _0.32 sacrificial layer
184 n-InAs _0.90 P _0.10 Strain carrier recombination prevention layer
185 n-InAs light absorption layer
186 p-InAs light absorption layer
1828 InP _0.68 Sb _0.32
221 InP _1-X Sb _X (0 ≦ X ≦ 0.30) metamorphic relaxation layer
223 n-InP _0.75 Sb _0.25 sacrificial layer
224 n-InAs _0.90 P _0.10 Light absorption layer
225 p-InGaAsP light absorption layer

Claims (10)

Having a light absorption layer including at least one pair of lattice mismatch relaxed P-type light absorption layer and N-type light absorption layer adjacent to each other;
The thickness d of the light absorbing layer is 0.5 μm ≦ d ≦ 5 μm,
The photoelectric conversion element, wherein the light absorption layer has a lattice constant a at room temperature of 5.886Å ≦ a ≦ 6.058Å. The light absorption layer is made of In _x Ga _1-x As (0.58 ≦ x ≦ 1), In _x Ga _1-x As _y P _1-y (0.58 ≦ x ≦ 1, 0.8 ≦ y <1) or InAs _z P _The photoelectric conversion element according to claim 1, comprising any one of _1-z (0.1 ≦ z ≦ 1). A P-type In _x Ga _1-xw Al _w As (0.58 ≦ x ≦ 1, 0.02 ≦ w ≦ 0.2) layer lattice-matched with the P _- type light absorption layer is formed adjacent to the P-type light absorption layer, or The N-type InAs _u P _1-u (0.1 ≦ u ≦ 0.9) layer lattice-matched to the N _- type light absorption layer is formed adjacent to the N-type light absorption layer. Photoelectric conversion element. Further comprising an antireflection film made of a dielectric provided on the light absorption layer,
The transmittance characteristic T (λ) of the antireflection film is 0 ≦ T (λ ₂ ) <0.5 <T (λ ₁ ) <1 and 1 μm ≦ λ with respect to the band gap wavelength λ _g (μm) of the light absorption layer. _The photoelectric conversion element according to any one of claims 1 to 3, wherein the conditions of ₁ ≦ λ _g and λ _g ≦ λ ₂ <5 μm are satisfied. Forming a metamorphic relaxation layer on the InP substrate;
Forming a sacrificial layer on the metamorphic relaxation layer;
Forming a light absorption layer including a P-type light absorption layer and an N-type absorption layer on the sacrificial layer;
Removing the sacrificial layer by an etching method;
Transferring the light absorbing layer from which the InP substrate and the metamorphic relaxation layer have been peeled off by the etching to any one of a transport base, a heat sink base, and a laminate base. A method for manufacturing a conversion element. The method for manufacturing a photoelectric conversion element according to claim 5, wherein at least a part of the lattice constant in the metamorphic relaxation layer increases stepwise or continuously from the lattice constant of InP to the lattice constant in the light absorption layer. The metamorphic relaxation layer is made of In _X Ga _1-X As (0.53 ≦ x ≦ 1), InAs _y P _1-y (0 ≦ y ≦ 1), AlAs _1-X Sb _X (0.44 ≦ x ≦ 0.84) or The method for producing a photoelectric conversion element according to claim 5, comprising at least one of InP _1-y Sb _y (0 ≦ y ≦ 0.32). The method for manufacturing a photoelectric conversion element according to claim 5, wherein the sacrificial layer is lattice-matched to the light absorption layer. 9. The method of manufacturing a photoelectric conversion element according to claim 5, wherein the sacrificial layer has a layer thickness d 2 of 20 nm ≦ d 2 ≦ 200 nm. The sacrificial layer includes at _{least one} of AlAs _1-X Sb _X (0.48 ≦ x ≦ 0.84) or InP _1-y Sb _y (0.05 ≦ y ≦ 0.32). The manufacturing method of the photoelectric conversion element of description.