CN204792857U

CN204792857U - Many son knot compound photovoltaic cell

Info

Publication number: CN204792857U
Application number: CN201520438166.1U
Authority: CN
Inventors: 司红康
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-06-25
Filing date: 2015-06-25
Publication date: 2015-11-18
Anticipated expiration: 2025-06-25

Abstract

The utility model relates to a many son knot compound photovoltaic cell specifically is three son knot compound photovoltaic cell of inAlAsPInGaAsGe, this three son knots compound photovoltaic cell have the protruding structure of continuous second order, and are protruding and protruding including the second rank on inclined plane including the prime that has the inclined plane, and high refractive index transparent material m2 forms the region between the arch of second rank, and top surface and the protruding a's in second rank top surface flushes and for smooth, high refractive index transparent material m1 forms the region between the prime arch, and the top surface flushes and contact high refractive index transparent material m2 with the bellied top surface of prime, material m1's refracting index is greater than material m2, and on the light that shines the battery top surface inclines shine the smooth surface of the protruding structure of second order, but greatly increased shines the light intensity on the smooth surface that has high -quality epitaxial layer to increase photoelectric conversion efficiency.

Description

A kind of many son knot compound photovoltaic cell

Technical field

The utility model relates to a kind of compound photovoltaic cell, and excellent its relates to a kind of many son knot compound photovoltaic cell.

Background technology

III-V compounds of group photovoltaic cell is used in space field at first, but along with the progress of Ji Intraoperative, III-V compounds of group photovoltaic cell also more and more applies to non-space field.Compared with Silicon photrouics, III-V compounds of group photovoltaic cell has larger energy conversion efficiency, and III-V its opto-electronic conversion of compounds of group photovoltaic cell produced by advanced technologies becomes efficiency can more than 25%, and Silicon photrouics can not more than 20%.Compared to Silicon photrouics, III-V compounds of group photovoltaic cell is changed to the maximization realizing many solar radiations by using multiple sub-battery with different band-gap energy.

For III-V compounds of group photovoltaic cell, GaInP/GaAs/Ge is the most typical a kind of III-V the most ripe compounds of group photovoltaic cell, its density of photocurrent can reach 25mA/cm2, but existing III-V compounds of group photovoltaic cell is also insufficient to the spectral absorption of natural sunlight, and be mostly to be successively extended in Semiconductor substrate with the formation of vertical, many knots, often can not form flocked surface light to confinement effect as Silicon photrouics, existing III-V compounds of group photovoltaic cell has further lifting to be obtained.

Utility model content

In order to make up the deficiency of existing III-V compounds of group photovoltaic cell, further raising is to the utilance of light, the utility model provides a kind of InAlAsP/IGaAs/Ge tri-to tie compound photovoltaic cell, this InAlAsP/InGaAs/Ge tri-junction structure can improve the conversion efficiency of photovoltaic cell effectively, this InAlAsP/IGaAs/Ge tri-knot compound photovoltaic cell also has and has the second order bulge-structure of confinement effect and the refraction structure to light formation refraction optimization to light simultaneously, this structure can improve light contact area effectively, can confinement effect efficiently be produced to light and optimize light position.

The utility model provides a kind of many son knot compound photovoltaic cell, and namely InAlAsP/InGaAs/Ge tri-knot compound photovoltaic cell, comprises Ge substrate; Ge battery, is positioned on Ge substrate; The sub-battery of InGaAs, is positioned on Ge battery; The sub-battery of InAlAsP, is positioned on the sub-battery of InGaAs; The back surface field layer on n++Ge contact layer and n++Ge contact layer is comprised between described Ge substrate and Ge battery; The sub-battery of InAlAsP is Window layer, Window layer is p++ contact layer; Ge battery and the sub-battery of InGaAs, there is before the sub-battery of InGaAs and the sub-battery of InAlAsP the n++/p++ tunneling diode of Lattice Matching, specifically described many son knot compound photovoltaic cell tops plane of illumination shape is continuous print second order bulge-structure, each second order bulge-structure has the first rank projection and second-order rises, and wherein second-order projection raises up from the upper surface of the first rank projection; Between second order bulge-structure, form high refractive index transparent material, described high refractive index transparent material comprises the second high refractive index transparent material in the region be formed between second-order projection and is formed in the first high refractive index transparent material in the region between the first rank projection; The end face of described second high refractive index transparent material flushes with the end face of second-order projection and is smooth; The end face of described first high refractive index transparent material flushes with the end face of the first rank projection and contacts the second high refractive index transparent material.

Further, the refractive index of described first high refractive index transparent material is greater than the refractive index of described second high refractive index transparent material.

Further, described Ge battery is comprising nGe base successively away from the direction of substrate, p+Ge emitter region, and the band gap with about 0.66eV; The sub-battery of described InGaAs is comprising nInGaAs base successively away from substrate direction, p+InGaAs emitter region, and the band gap with about 1.40eV; The sub-battery of the institute InAlAsP that tells is comprising nInAlAsP base successively away from substrate direction, p+InAlAsP emitter region, and has the band gap of about 1.90eV.

Further, the bottom thickness from the end face of second-order projection to Ge substrate is 300 ~ 400 μm, and the thickness of protruding bottom surface to the first rank, top of the first rank projection is 50 ~ 80 μm; And the top of second-order projection is at least greater than the twice of top thickness of protruding bottom surface to the first rank of the first rank projection to the thickness at the top of the first rank projection; Interval between every two second order bulge-structures is less than the thickness of protruding bottom surface to the first rank, top of the first rank projection.

Further, the n++/p++ tunnel-through diode of described Lattice Matching is heterojunction tunnel-through diode.

Further, the n++/p++ tunnel-through diode of described Lattice Matching is n++InGaP/p++InGaAsP heterojunction tunnel-through diode; Its gross thickness is 30-45 nanometer.

Accompanying drawing explanation

Fig. 1 is the structural representation of three son knot compound photovoltaic cell;

Fig. 2 is the enlarged drawing of a-quadrant in Fig. 1, i.e. photovoltaic cell each son knot material layer schematic diagram;

Fig. 3 is the structural representation that the utility model has three son knot compound photovoltaic cell of high refractive transparent material.

Embodiment

Be described further the utility model below with reference to preferred forms, the beneficial effects of the utility model will become clear in describing in detail.

See the structural representation that Fig. 1-3, Fig. 1 is three sub-junction photovoltaic batteries, Fig. 2 is the enlarged drawing of a-quadrant in Fig. 1, which show the details of the utility model photovoltaic cell, an aspect of the present utility model, there is see Fig. 2 compound photovoltaic cell of the present utility model the InAlAsP/InGaAs/Ge structure of many son knots, wherein the band gap of the sub-battery of InAlAsP (300) is at about 1.9eV, the band gap of the sub-battery of InGaAs (200) is at about 1.40eV, the band gap of Ge battery (100) is about 0.66eV, optimizing structure of the band gap that three junction photovoltaic batteries of the present utility model have can mate the wavelength structure of nature solar spectrum, make full use of the photon energy of each wavelength period of photovoltaic, optimize the absorption to solar spectrum on the whole, improve battery efficiency.And, see Fig. 1, compound photovoltaic cell top of the present utility model plane of illumination shape is continuous print second order bulge-structure (a, b), each second order bulge-structure (a, b) have the first rank projection (b) and second-order projection (a), wherein second-order projection (a) raises up from the upper surface on the first rank projection (b).

See Fig. 2, be positioned on Ge substrate (001) and be followed successively by Ge battery (100), the sub-battery of InGaAs (200), the sub-battery of InAlAsP (300) to form three junction batteries of 1.90eV/1.40eV/0.66eV band structure.Wherein the band gap of each sub-battery is progressively increasing away from the direction of substrate, this is extremely conducive to the raising of density of photocurrent, wherein Ge battery (100) have about 0.66eV band gap and away from the direction of substrate being followed successively by nGe base (101), p+Ge emitter region (102), nGe base (101) thickness is preferably 2.5 microns, and p+Ge emitter region (102) thickness is preferably 80-100 nanometer; The sub-battery of InGaAs (200) has the band gap of about 1.40eV, and away from the direction of substrate being followed successively by nInGaAs base (201), p+InGaAs emitter region (202), the thickness of nInGaAs base (201) is preferably 2.2 microns, and the thickness of p+InGaAs emitter region (202) is preferably 80-100 nanometer; The sub-battery of InAlAsP (300) has the band gap of about 1.90eV, and away from the direction of substrate being followed successively by nInAlAsP base (301), p+InAlAsp emitter region (302), the thickness of nInAlAsP base (301) is preferably 1.8-2.0 micron, and the thickness of p+InAlAsp emitter region (302) is preferably 80-100 nanometer.N++Ge contact layer (002) and back surface field layer (003) is also comprised between Ge substrate (001) and nGe base (101); Upper at the sub-battery of InAlAsP (300) is Window layer (006), Window layer (006) is upper is p++ contact layer (007), is less than the little sub-battery away from plane of illumination of energy gap in the utility model for the sub-battery being optimized for the large close plane of illumination of energy gap of each sub-battery base thickness; Specifically, the thickness being exactly nInAlAsP base (301) is less than the thickness of nInGaAs base (201), the thickness of nInGaAs base (201) is less than the thickness of nGe base (101), is conducive to the maximum using to natural photovoltaic spectrum like this.

There is the n++/p++ tunnel-through diode (004,005) of Lattice Matching between each sub-battery layers; can with in the multi-junction photovoltaic battery of system at this InAlAsP/InGaAs/Ge, the n++/p++ tunnel-through diode of Lattice Matching needs to select heterojunction structure, this is conducive to provide potential barrier between high knot, tunnel-through diode (005) particularly between the sub-battery of InAlAsP and InGaAs, in our experiment, observe this by son diffusion few between the sub-battery of the InAlAsP on upper strata (300) and minimizing knot, favourable effect is played to light, we used n++InGaP/p++InGaAsP heterojunction tunnel-through diode in an experiment, this improves the photoelectric current efficiency of battery to the full extent, certainly as epitaxially grown many knots III-V race's photovoltaic cell, the thickness of tunnel-through diode is very important and responsive, when selecting n++InGaP/p++InGaAsP heterojunction tunnel-through diode as tunnel-through diode (005) between the sub-battery of body series multi-junction photovoltaic battery InAlAsP and InGaAs, the gross thickness of the n++InGaP/p++InGaAsP heterojunction tunnel-through diode (005) of optimum experimental is 30-45 nanometer.

This compound photovoltaic cell comprises and has continuous print second order bulge-structure (a, b) Ge substrate (001), second order bulge-structure (a of InAlAsP/InGaAs/Ge tri-junction photovoltaic battery, b) be based upon on the Ge substrate of second order bulge-structure, each sub-battery and other functional layers are covered on this Ge substrate successively.The second order bulge-structure of InAlAsP/InGaAs/Ge tri-junction photovoltaic battery.First the second order bulge-structure (a, b) of the utility model InAlAsP/InGaAs/Ge tri-junction photovoltaic battery is based upon on the Ge substrate of second order bulge-structure, and each sub-battery and other functional layers are covered on this Ge substrate successively.Bottom thickness d1 from the end face of second-order projection (b) to Ge substrate is about 300-400 μm, and the top on the first rank projection (b) is preferably 50 ~ 80 μm to the bottom surface d2 on the first rank projection (b), and namely the height d2 on the first rank projection (b) is 50 ~ 80 μm; The top of second-order projection (a) to the first rank projection (a) top between thickness d 3 be at least greater than the twice of the height d2 on the first rank projection (b), be preferably 150 ~ 200 μm, namely the height d3 of second-order projection (a) is preferably 150 ~ 200 μm; Interval between every two second order bulge-structures is less than the height on the first rank projection (b); The width of each second order bulge-structure is preferably 150 ~ 200 μm.By the optimization of above-mentioned parameter, when incident ray is irradiated to photovoltaic cell surface at a certain angle, first a part is absorbed on the surface of second-order bulge-structure by battery, the unabsorbed part being irradiated to the second bulge-structure side reflexes to the surface of the first rank projection and is absorbed by the first rank projection, and can not reflexed on the battery surface between second order projection cube structure by the light of a first rank projection cube structure Surface absorption part.Thus and thus, make originally to utilize the light being irradiated to battery upper surface, tightly the light being irradiated to upper surface can not be utilized by second order bulge-structure, can also utilize by the reflection of side the light being irradiated to side more, this part light is exactly the additional light rays increased, in a way, this structure has carried out the utilization of architecture light, therefore can reach maximized utilization to solar incident ray.Even more noteworthy, the light reflected from the battery surface between second order projection cube structure again can the surface of directive first rank projection cube structure and/or the surface of second-order projection cube structure, photovoltaic light like this is maximized ground confinement on the surface of photovoltaic cell with second order projection cube structure, and the utilization of battery to sunray is greatly improved; Can realize above-mentioned limit neck effect is inseparable with above-mentioned parameter choose, if the interval that the height of second-order projection is less than between the height of the first rank projection or second order bulge-structure too mostly can not be played confinement effect to sunray or can greatly slacken confinement effect.

From above-mentioned analysis, the utilization of bulge-structure to sunlight with vertical side is optimized, but, formed in practical cell process, formed by epitaxy technology, epitaxy technology is undesirable often to the deposition of vertical side, during such as, active layer for each battery of extension, can form stress at knuckle place to concentrate, this can have influence on cell integrated performance; Simultaneously; often uneven thickness is there will be in the outer time delay of vertical side; this is also the restriction factor affecting battery performance; under actual conditions; the side of the first and second projections is compared with smooth surface; photoelectric conversion efficiency can be much lower, therefore design a kind of make light maximum to be irradiated to the solar cell that smooth surface has second order bulge-structure to the utility model be very significant.

As Fig. 3, in order to favourable light is towards the smooth surface irradiation of battery, high refractive index transparent material m1(material1 is formed between second order bulge-structure) and m2(material2), high refractive index transparent material m2 is formed in the region between second-order projection, and end face flushes with the end face of the protruding a of second-order and is smooth; High refractive index transparent material m1 is formed in the region between the first rank projection, and end face flushes with the end face of the first rank projection and contacts high refractive index transparent material m2.As light L1 with certain angular illumination to battery surface, the place had a common boundary at air and m2 reflects, the light being originally irradiated to second order bulge-structure side is made to be more prone to be irradiated on the flat surfaces of second order bulge-structure, so just considerably increase the light intensity be irradiated on the flat surfaces with high-quality epitaxial loayer, thus increase photoelectric conversion efficiency.Further, the refractive index of high refractive index transparent material m1 is greater than m2, the light L2 reflected through high refractive index transparent material m2 like this can be irradiated to the side of the first rank projection originally, but in the interface of material m2 and material m1 through another refraction, L2 is made to tend on the flat surfaces of the high-quality epitaxial loayer be irradiated between second order bulge-structure, so will promote the performance of battery further, what high index of refraction described in the utility model represented is than ambient refractive index and the high refractive index of air refraction, can be silicon dioxide as preferred embodiment high refractive index transparent material m2, high refractive index transparent material m1 can be titanium oxide, the refractive index of high refractive index transparent material m1 be greater than high refractive index transparent material m2 refractive index 20% and more than.

For this second order bulge-structure other parameters arrange as follows: the bottom thickness d1 from the end face of second-order projection (b) to Ge substrate is about 300-400 μm, the top on the first rank projection (b) is preferably 50 ~ 80 μm to the bottom surface d2 on the first rank projection (b), and namely the height d2 on the first rank projection (b) is 50 ~ 80 μm; The top of second-order projection (a) to the first rank projection (a) top between thickness d 3 be at least greater than the twice of the height d2 on the first rank projection (b), be preferably 150 ~ 200 μm, namely the height d3 of second-order projection (a) is preferably 150 ~ 200 μm; Interval between every two second order bulge-structures is less than the height on the first rank projection (b); The width of each second order bulge-structure is preferably 150 ~ 200 μm.Limit neck effect more can be optimized, if the interval that the height of second-order projection is less than between the height of the first rank projection or second order bulge-structure too mostly can not be played confinement effect to sunray or can greatly slacken confinement effect by above-mentioned parameter.

By the description of above-mentioned specific embodiment, disclose design of the present utility model very all sidedly, those skilled in the art should understand advantage part of the present utility model; Understanding for the application should not limit in the above-described embodiments, and the execution mode of the obvious distortion consistent with the utility model spirit also should belong to design of the present utility model.

Claims

1. the knot of son a more than compound photovoltaic cell, namely InAlAsP/InGaAs/Ge tri-knot compound photovoltaic cell, comprises Ge substrate; Ge battery, is positioned on Ge substrate; The sub-battery of InGaAs, is positioned on Ge battery; The sub-battery of InAlAsP, is positioned on the sub-battery of InGaAs; The back surface field layer on n++Ge contact layer and n++Ge contact layer is comprised between described Ge substrate and Ge battery; The sub-battery of InAlAsP is Window layer, Window layer is p++ contact layer; Ge battery and the sub-battery of InGaAs, there is before the sub-battery of InGaAs and the sub-battery of InAlAsP the n++/p++ tunneling diode of Lattice Matching, it is characterized in that: described many son knot compound photovoltaic cell tops plane of illumination shape is continuous print second order bulge-structure, each second order bulge-structure has the first rank projection and second-order rises, and wherein second-order projection raises up from the upper surface of the first rank projection; Between second order bulge-structure, form high refractive index transparent material, described high refractive index transparent material comprises the second high refractive index transparent material in the region be formed between second-order projection and is formed in the first high refractive index transparent material in the region between the first rank projection; The end face of described second high refractive index transparent material flushes with the end face of second-order projection and is smooth; The end face of described first high refractive index transparent material flushes with the end face of the first rank projection and contacts the second high refractive index transparent material.

2. many son knot compound photovoltaic cell batteries as claimed in claim 1, is characterized in that: the refractive index of described first high refractive index transparent material is greater than the refractive index of described second high refractive index transparent material.

3. many son knot compound photovoltaic cell as claimed in claim 1, is characterized in that: described Ge battery is comprising nGe base successively away from the direction of substrate, p+Ge emitter region, and the band gap with about 0.66eV; The sub-battery of described InGaAs is comprising nInGaAs base successively away from substrate direction, p+InGaAs emitter region, and the band gap with about 1.40eV; The sub-battery of the institute InAlAsP that tells is comprising nInAlAsP base successively away from substrate direction, p+InAlAsP emitter region, and has the band gap of about 1.90eV.

4. many son knot compound photovoltaic cell as claimed in claim 3, the bottom thickness from the end face of second-order projection to Ge substrate is 300 ~ 400 μm, and the thickness of protruding bottom surface to the first rank, top of the first rank projection is 50 ~ 80 μm; And the top of second-order projection is at least greater than the twice of top thickness of protruding bottom surface to the first rank of the first rank projection to the thickness at the top of the first rank projection; Interval between every two second order bulge-structures is less than the thickness of protruding bottom surface to the first rank, top of the first rank projection.

5. many son knot compound photovoltaic cell as claimed in claim 1, the n++/p++ tunnel-through diode of described Lattice Matching is heterojunction tunnel-through diode.

6. many son knot compound photovoltaic cell as claimed in claim 5, the n++/p++ tunnel-through diode of described Lattice Matching is n++InGaP/p++InGaAsP heterojunction tunnel-through diode; Its gross thickness is 30-45 nanometer.