WO2010126290A1 - Dispositif à semi-conducteurs - Google Patents

Dispositif à semi-conducteurs Download PDF

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WO2010126290A1
WO2010126290A1 PCT/KR2010/002655 KR2010002655W WO2010126290A1 WO 2010126290 A1 WO2010126290 A1 WO 2010126290A1 KR 2010002655 W KR2010002655 W KR 2010002655W WO 2010126290 A1 WO2010126290 A1 WO 2010126290A1
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active layer
compound
semiconductor device
barrier layer
polarization field
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PCT/KR2010/002655
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English (en)
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Doyeol Ahn
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University Of Seoul Industry Cooperation Foundation
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Priority claimed from US12/430,406 external-priority patent/US20100270592A1/en
Priority claimed from US12/430,424 external-priority patent/US20100270547A1/en
Priority claimed from US12/431,921 external-priority patent/US20100276730A1/en
Priority claimed from US12/431,930 external-priority patent/US8253145B2/en
Application filed by University Of Seoul Industry Cooperation Foundation filed Critical University Of Seoul Industry Cooperation Foundation
Publication of WO2010126290A1 publication Critical patent/WO2010126290A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/12—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
    • H01L29/20—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only AIIIBV compounds
    • H01L29/201—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only AIIIBV compounds including two or more compounds, e.g. alloys
    • H01L29/205—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only AIIIBV compounds including two or more compounds, e.g. alloys in different semiconductor regions, e.g. heterojunctions
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/32—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/12—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
    • H01L29/20—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only AIIIBV compounds
    • H01L29/2003—Nitride compounds
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
    • H01L29/76—Unipolar devices, e.g. field effect transistors
    • H01L29/772—Field effect transistors
    • H01L29/778—Field effect transistors with two-dimensional charge carrier gas channel, e.g. HEMT ; with two-dimensional charge-carrier layer formed at a heterojunction interface
    • H01L29/7786—Field effect transistors with two-dimensional charge carrier gas channel, e.g. HEMT ; with two-dimensional charge-carrier layer formed at a heterojunction interface with direct single heterostructure, i.e. with wide bandgap layer formed on top of active layer, e.g. direct single heterostructure MIS-like HEMT
    • H01L29/7787—Field effect transistors with two-dimensional charge carrier gas channel, e.g. HEMT ; with two-dimensional charge-carrier layer formed at a heterojunction interface with direct single heterostructure, i.e. with wide bandgap layer formed on top of active layer, e.g. direct single heterostructure MIS-like HEMT with wide bandgap charge-carrier supplying layer, e.g. direct single heterostructure MODFET
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/04—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a quantum effect structure or superlattice, e.g. tunnel junction
    • H01L33/06—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a quantum effect structure or superlattice, e.g. tunnel junction within the light emitting region, e.g. quantum confinement structure or tunnel barrier
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/30—Structure or shape of the active region; Materials used for the active region

Definitions

  • the present invention relates to semiconductor devices having at least one barrier layer with a wide energy band gap.
  • Group M-V compound, Group II- VI compound, and Group I- VII compound semiconductors have particularly wide band gaps and are capable of emitting green or blue light.
  • semiconductor devices such as photo-electric conversion devices using III- V, II- VI, or I- VII group compound semiconductor crystals as base materials have been developed to improve efficiency and life time of the semiconductor devices.
  • a semiconductor device includes at least one active layer composed of a first compound, and at least one barrier layer composed of a second compound and disposed on at least one surface of the at least one active layer.
  • the at least one barrier layer may have a wider energy band gap than an energy band gap of the at least one active layer.
  • the compositions of the first and the second compounds may be controlled to reduce an internal polarization field in the at least one active layer.
  • FIGS. l(a) and (b) are schematic diagrams of an illustrative embodiment of a semiconductor device.
  • FIGS. 2(a) and (b) are schematic diagrams showing band gaps of the semiconductor devices of FIG. 1.
  • FIGS. 3 (a) and (b) are schematic diagrams illustrating an electron-phonon scattering and a carrier-carrier scattering, respectively.
  • FIG. 4 is a schematic diagram of an illustrative embodiment of a M-V group compound semiconductor device.
  • FIG. 5 is a graph showing an internal polarization field as a function of In composition of the AlGaInN barrier layer shown in FIG. 4.
  • FIG. 6 is a graph showing the relationship between In composition of the InGaN active layer and In composition of the AlGaInN barrier layer shown in FIG. 4.
  • FIG. 7 is a graph showing quasi-Fermi level separation as a function of In composition of the InGaN active layer shown in FIG. 4.
  • FIG. 8 is a graph showing a peak optical gain (y-axis) of the InGaN/AlGalnN semiconductor device as a function of In composition of the InGaN active layer (x-axis) shown in FIG. 4.
  • FIG. 9 is a graph showing the relationship between an internal polarization field and a scattering rate in the III- V group compound semiconductor device of FIG. 4.
  • FIG. 10 is a graph showing normalized optical matrix elements as a function of in- plane vectors for different compositions of the barrier layer shown in FIG. 4.
  • FIG. 11 is a graph showing an optical gain as a function of a wavelength for the
  • InGaN/ AlGaInN semiconductor device shown in FIG. 4 and a InGaN/GaN semiconductor device.
  • FIG. 12 is a schematic diagram of an illustrative embodiment of a II- VI group compound semiconductor device.
  • FIG. 13 is a graph showing an internal polarization field as a function of Mg composition of the MgZnO barrier layer for different mole fractions of Cd composition of the CdZnO active layer shown in FIG. 12.
  • FIG. 14 shows graphs illustrating (a) the relationship between Mg composition of the
  • MgZnO barrier layer and Cd composition of the CdZnO active layer shown in FIG. 12 (b) a wavelength of the semiconductor device shown in FIG. 9 as a function of Cd composition of the CdZnO active layer shown in FIG. 12.
  • FIG. 15 shows graphs illustrating (a) an optical gain as a function of a wavelength for different mole fractions of Cd compositions of the CdZnO active layer shown in FIG. 12, and (b) an optical gain as a function of different mole fractions of Cd composition of the CdZnO active layer shown in FIG. 12.
  • FIG. 16 is a schematic diagram of an illustrative embodiment of a I- VII group compound semiconductor device.
  • FIGS. 17(a)-(e) are schematic diagrams illustrating an illustrative embodiment of a method for fabricating a semiconductor device. Mode for the Invention
  • a semiconductor device includes at least one active layer composed of a first compound, and at least one barrier layer composed of a second compound and disposed on at least one surface of the at least one active layer.
  • An energy band gap of the at least one barrier layer may be wider than an energy band gap of the at least one active layer.
  • the compositions of the first compound and the second compound may be controlled to reduce an internal polarization field in the at least one active layer.
  • compositions of the first and/or second compounds can be controlled to make a sum of piezoelectric and spontaneous polarizations in the at least one active layer and a sum of piezoelectric and spontaneous polarizations in the at least one barrier layer substantially the same to reduce the internal polarization field.
  • Each of the first and second compounds can include a III- V group compound semiconductor material, a II- VI group compound semiconductor material, or I- VII group compound semiconductor material.
  • the first compound can include GaN, InGaN, CdZnO, AlN, AlP, AlAs, GaP, GaAs, InN, InP, InAs, AlGaN, AlGaP, AlGaAs, InGaN, InGaP, InGaAs, InAlN, InAlP, InAlAs, AlGaInN, AlGaInP, AlGaInAs, ZnO, ZnS, CdO, CdS, CdZnS, CdZnO, MgZnO, MgZnS, CdMgZnO, CdMgZnS, CuF, CuCl, CuBr, CuI, AgF, AgCl, AgBr, AgI, AuF, AuCl, AuBr, Au
  • the second compound can include AlInGaN, InGaN, AlGaN, AlGaP, AlGaAs, InGaN, InGaP, InGaAs, InAlN, InAlP, InAlAs, AlGaInP, AlGaInAs, CdZnS, CdZnO, MgZnO, MgZnS, CdMgZnO, CdMgZnS, CuFCl, CuBrF, CuFI, CuClBr, CuClI, CuBrI, AgFCl, AgFBr, AgFI, AgClBr, AgClI, AgBrI, AuFCl, AuFBr, AuFI, AuClBr, AuClI, AuBrI, AuBrI, AuBrI, AuBrI, AuBrI, AuBrI, CuFClBr, CuFClI, CuFBrI, CuIBrClCl, AgFBrI,
  • the first compound can include In x Ga 1 ⁇ N (O ⁇ x ⁇ l) and the second compound can include AI y1 Ga 1 ⁇ y2 In 511 N (0 ⁇ yl+y2 ⁇ l).
  • Variable x can be in the range of about 0.05 and 0.15
  • variable y 1 can be in the range of about 0.05 to 0.3
  • variable y2 can be in the range of about 0.1 and 0.22.
  • the first compound can include Cd x Zn 1 x O (O ⁇ x ⁇ l) and the second compound can include Mg y Zn ⁇ y O (O ⁇ y ⁇ l).
  • Variable x can be in the range of about 0 and 0.20, and variable y can be in the range of about 0.01 and 0.80.
  • the first compound can include CuBr x F 1 ⁇ (O ⁇ x ⁇ l), and the second compound can include CuI y1 Br 1 . y1 . y2 Cl y2 (0 ⁇ yl+y2 ⁇ l).
  • Variable x can be in the range of about 0.03 and 0.5
  • variable yl can be in the range of about 0.01 to 0.4
  • variable y2 can be in the range of about 0.2 and 0.35.
  • An optical gain of the semiconductor device can be substantially identical to or greater than 14,000/cm.
  • a method for fabricating a semiconductor device includes forming at least one active layer composed of a first compound on a substrate, forming at least one barrier layer composed of a second compound on at least one surface of the at least one active layer, and reducing an internal polarization field in the at least one active layer by controlling compositions of the first compound and/or the second compound.
  • An energy band gap of the at least one barrier layer can be wider than an energy band gap of the at least one active layer.
  • the internal polarization field can be reduced by controlling the compositions of the first compound and the second compound to increase a difference between Fermi functions for conduction band and valence band in the at least one active layer, to reduce a relaxation time of an electron or hole in the at least one active layer, to increase an optical dipole matrix element of the at least one active layer, or to strengthen an excitonic binding between an electron and a hole in the at least one active layer.
  • Each of the first and second compounds can include III-V group compound semiconductor material, II- VI group compound semiconductor material or I- VII group compound semiconductor material.
  • the at least one active layer and the at least one barrier layer can be formed by employing radio-frequency (RF) magnetron sputtering, pulsed laser deposition, metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy or radio- frequency plasma-excited molecular beam epitaxy.
  • RF radio-frequency
  • MOCVD metal organic chemical vapor deposition
  • the compositions of the first and/ or second compounds can be adjusted by controlling an amount of precursor gases or by controlling a processing temperature or processing time to adjust the difference between the Fermi functions for conduction band and valence band in the at least one active layer.
  • FIGS. l(a) and (b) are schematic diagrams of an illustrative embodiment of a semiconductor device 100.
  • FIG. 2(a) and (b) are schematic diagrams showing band gaps of semiconductor device 100.
  • semiconductor device 100 may have a single het- erostructure in which a barrier layer 110 is disposed on one surface (e.g., a top surface) of an active layer 120.
  • Barrier layer 110 has a wider band gap that is wider than the band gap of active layer 120.
  • a band gap (E g actlve i ayer ) 220 of active layer 120 is lower than a band gap (E gibamer layer ) 210 of barrier layer 110, so that a quantum well 240 is formed in active layer 120.
  • E &actlve layer is the difference between E c and E v at active layer 12O 1 and E gibamer layer is the difference between E c and E v at barrier layer 110.
  • E c refers to an energy level at a conduction band of a semiconductor material, for example, a M-V group, II- VI group, or I- VII group compound semiconductor material.
  • E v refers to an energy level at a valence band of a semiconductor material, for example, a M-V group, II- VI group, or I- VII group compound semiconductor material.
  • Quantum well 240 is a thin layer which can confine carriers, such as electrons or holes, in a dimension perpendicular to a surface of the thin layer. Due to the band gap differences between active layer 120 and barrier layer 110, particles, such as electrons or holes can be confined in quantum well 240.
  • semiconductor device 100 may optionally have a second barrier layer (e.g., a barrier layer 130), and thus form a double heterostructure.
  • semiconductor device 100 may have active layer 120, barrier layer 110 disposed on one surface (e.g., a top surface) of active layer 120 and a barrier layer 130 disposed on the other surface (e.g., a bottom surface) of active layer 120.
  • barrier layers 110 and 130 are hereinafter referred as upper barrier layer 110 and lower barrier layer 130.
  • Each barrier layer 110 or 130 has a wider band gap than that of active layer 120.
  • Quantum well 240 is also formed in active layer 120 because of the differences between band gap (E g , actlve layer ) 220 of active layer 120 and band gap (E g>upperbamer layer ) 210 of upper barrier layer 110 and a band gap (E g , lowerbamer i ayer ) 230 of lower barrier layer 130, as depicted in FIG. 2(b).
  • Active layer 120 may be composed of a M-V group compound semiconductor material, a II- VI group compound semiconductor material, or a I-V group compound semiconductor material.
  • M-V group semiconductor material includes, without limitation, GaN, InGaN, AlN, AlP, AlAs, GaP, GaAs, InN, InP, InAs, AlGaN, AlGaP, AlGaAs, InGaN, InGaP, InGaAs, InAlN, InAlP, InAlAs, AlGaInN, AlGaInP or AlGaInAs.
  • the II- VI group semiconductor material includes, without limitation, ZnO, ZnS, CdO, CdS, CdZnO, CdZnS, MgZnO, MgZnS, CdMgZnO or CdMgZnS.
  • the I- VII group semiconductor material includes, without limitation, CuF, CuCl, CuBr, CuI, AgF, AgCl, AgBr, AgI, AuF, AuCl, AuBr, AuI, CuFCl, CuBrF, CuFI, CuClBr, CuClI, CuBrI, AgFCl, AgFBr, AgFI, AgClBr, AgClI, AgBrI, AuFCl, AuFBr, AuFI, AuClBr, AuClI, AuBrI, CuFClBr, CuFClI, CuFBrI, CuIBrCl, AgFClBr, AgFClI, AgFBrI, AgClBrI, AuFClI, AuFBrI, AuFBrI, AuBrI, AuBrI, CuFClBr, CuFClI, CuFBrI, CuIBrCl, AgFClI, AgFBrI, AgClBrI, AuFClI, AuFB
  • Each of upper and lower barrier layers 110 and 130 in FIG. 1 may be composed of a
  • each of upper and lower barrier layers 110 and 130 may also include a ternary compound semiconductor material or a quaternary compound semiconductor material.
  • each of barrier layers 110 and 130 may include a M-V group compound semiconductor material, a II- VI group compound semiconductor, or a I- VII group compound semiconductor material.
  • the M-V group compound semiconductor material may include, without limitation, AlInGaN, InGaN, AlGaN, AlGaP, AlGaAs, InGaN, InGaP, InGaAs, InAlN, InAlP, InAlAs, AlGaInP or AlGaInAs.
  • the II- VI group compound semiconductor material may include, without limitation, CdZnS, MgZnS, CdZnO, MgZnO, CdMgZnO or CdMgZnS.
  • the I- VII group compound semiconductor material may include, without limitation, CuFCl, CuBrF, CuFI, CuClBr, CuClI, CuBrI, AgFCl, AgFBr, AgFI, AgClBr, AgClI, AgBrI, AuFCl, AuFBr, AuFI, AuClBr, AuClI, AuBrI, CuFClBr, CuFClI, CuFBrI, CuIBrCl, AgFClBr, AgFClI, AgFBrI, AgClBrI, AuFClI, AuFBrI, or AuClBrI.
  • Upper and lower barrier layers 110 and 130 may each have a thickness of about O.lnm to 500nm, or about lnm to lOOnm.
  • semiconductor device 100 can have two or more active layers and two or more barrier layers.
  • the two or more active layers and the two or more barrier layers can be sequentially deposited to form a sandwiched configuration in which an active layer is sandwiched with two barrier layers.
  • a quantum efficiency is a quantity defined as the percentage of photons that produces an electron-hole pair, and can be measured by, for example, an optical gain of semiconductor device 100.
  • the optical gain g( ⁇ ) can be calculated by using a non- Markovian model with many-body effects due to interband transitions.
  • the "many- body effects” refer to a band gap renormalization and an enhancement of optical gain due to attractive electron-hole interaction (Coulomb or excitonic enhancement).
  • the optical gain g( ⁇ ) is given by Equation (1) as below . For theory on the optical gain, see Doyeol Ahn, "Theory of Non-Markovian Gain in Strained-Layer Quantum- Well Lasers with Many-Body Effects", IEEE Journal of Quantum Electronics, Vol.
  • ⁇ is an angular frequency of photon in active layer 120; ⁇ is a vacuum permeability; n r is a refractive index of active layer 120; c is the speed of light in free space; V is the volume of active layer 120; f c and f h ⁇ are Fermi functions for conduction band and valence band of 3x3 block Hamiltonian H ⁇ , respectively; is a dipole matrix element between the conduction band with a spin state ⁇ and the valence band of the 3x3 block Hamiltonian H ⁇ ; ⁇ is an unit vector in the direction of the photon polarization; and
  • the optical gain g( ⁇ ) is proportional to the difference between Fermi functions for conduction band and valence band of the 3x3 block Hamiltonian H ⁇ , i.e. (f c -f h ⁇ ).
  • the Fermi function difference (f c -f h ⁇ ) relates to the separation of a quasi-Fermi level at steady state.
  • the quasi Fermi level describes a new Fermi level that each type of charge carriers, such as electrons and holes in a semiconductor appears to share when their populations are displaced from equilibrium. This displacement could be caused by the application of an electric potential, such as the electric potential caused by an internal polarization field existing in active layer 120.
  • Equation (2) r /;g (/7 ) _ l + Re g2 ( oc , ⁇ ( ⁇ , ))
  • Equation (2) [48] where the function g 2 is presented by the Equation (3) below.
  • the optical gain g( ⁇ ) decreases as the relaxation time ⁇ in increases according to Equation (1).
  • the relaxation time refers to the time period during which a carrier, such as an electron or hole, transits from a steady state to an equilibrium state.
  • a carrier emits energy in the form of, for example, light, corresponding to the band gap between the steady state and the equilibrium state in quantum well 240 while the carrier undergoes the transition.
  • the optical gain g( ⁇ ) will increase.
  • the relaxation time is related to an electron-phonon scattering and a carrier-carrier scattering in quantum well 240.
  • FIG. 3 (a) and (b) show schematic diagrams illustrating an electron-phonon scattering and a carrier-carrier scattering, respectively.
  • the electron-phonon scattering refers to a situation where that a hole 320 is scattered due to the emission or absorption of phonon from or into an electron 310 (FIG. 3(a)).
  • the carrier-carrier scattering refers to a situation where two electrons 330 and 340 collide and each scatter toward two holes 350 and 360. As the scatterings increase, the relaxation time ⁇ in increases because the excited electrons and holes less frequently collide.
  • the scatterings are related to the intensity of an internal polarization field in quantum well 240.
  • the internal polarization field exists in quantum well 240, it pushes electrons or holes to a wall of quantum well 240.
  • the effective well width is reduced, and the reduction results in the enhancement of the scattering rate.
  • the scattering rate can be decreased, and thus the relaxation time ⁇ in can be decreased. As illustrated above, this results in the enhancement of the optical gain of quantum well 240.
  • optical gain g( ⁇ ) increases in accordance with the increase of an optical dipole matrix element
  • optical dipole matrix element in quantum well 240.
  • the reduction of the internal polarization field causes the enhancement of the optical dipole matrix element, the decrease of the relaxation time of carriers, and the increase of the Fermi function difference in active layer 120.
  • the distance between electrons and holes in active layer 120 of semiconductor device 100 can be shortened.
  • the excitonic binding of electron-hole pairs in active layer 120 is increased and thus the optical gain of semiconductor device 100 is enhanced. Accordingly, the optical gain of semiconductor device 100 can be enhanced by reducing the internal polarization field in active layer 120.
  • the internal polarization field in quantum well 240 arises from spontaneous polarization P SP and piezoelectric polarization P PZ .
  • Piezoelectric polarization P PZ refers to polarization that arises from an electric potential generated in response to applied mechanical stress, such as strain of a layer.
  • Spontaneous polarization P SP refers to po- larization that arises in ferroelectrics without an external electric field.
  • the optical gain g( ⁇ ) is increased when a total internal polarization field that includes spontaneous and piezoelectric polarizations P SP and P sz , is reduced.
  • the total internal polarization field F z w in quantum well 240 can be determined from the difference between the sum of P SP and P PZ in quantum well 240 and the sum of P SP and P PZ in upper barrier layer 110 and lower barrier layer 130 and be presented by Equation (6) below.
  • internal polarization field F z w can have a value of zero by making the sum (P SP b + P PZ b ) of the spontaneous and piezoelectric polarizations at upper and lower barrier layers 110 and 130 and the sum (P SP W + P PZ b ) of the spontaneous and piezoelectric polarizations at quantum well 240 the same.
  • this can be achieved by controlling the mole fractions of the compound in upper and lower barrier layers 110 and 130, and/or active layer 120.
  • FIG. 4 is a schematic diagram of an illustrative embodiment of a III- V group compound semiconductor device.
  • FIG. 5 is a graph showing internal polarization field as a function of indium (In) composition of the AlGaInN barrier layer depicted in FIG. 4.
  • FIG. 6 is a graph showing the relationship between In composition of the InGaN active layer and In composition of the AlGaInN barrier layer depicted in FIG. 4.
  • FIG. 7 is a graph showing quasi-Fermi level separation as a function of In composition of the InGaN active layer depicted in FIG. 4.
  • FIG. 5 is a graph showing internal polarization field as a function of indium (In) composition of the AlGaInN barrier layer depicted in FIG. 4.
  • FIG. 6 is a graph showing the relationship between In composition of the InGaN active layer and In composition of the AlGaInN barrier layer depicted in FIG. 4.
  • FIG. 7 is a graph showing quasi-Fermi level separation as
  • FIG. 8 is a graph showing the peak optical gain (y-axis) of the InGaN/ AlGaInN semiconductor device as a function of In composition of the InGaN active layer (x-axis) depicted in FIG. 4.
  • FIG. 9 is a graph showing the relationship between an internal polarization field and a scattering rate in the M-V group compound semiconductor device of FIG. 4.
  • FIG. 10 is a graph showing normalized optical matrix elements as a function of in-plane vectors for different compositions of the barrier layer shown in FIG. 4.
  • FIG. 11 is a graph showing an optical gain as a function of a wavelength for the InGaN/ AlGaInN semiconductor device depicted in FIG. 4 and a InGaN/GaN semiconductor device.
  • a M-V group compound semiconductor device 400 includes an InGaN active layer 420 (i.e., an active layer composed of InGaN) and an AlGaInN barrier layer 410 (i.e. a barrier layer composed of AlGaInN) disposed on InGaN active layer 420.
  • M-V group compound semiconductor device 400 may further have additional barrier layer disposed under one surface (e.g., bottom surface) of InGaN active layer 420.
  • InGaN active layer 420 has a thickness of several nanometers to several hundreds nanometers (nm). In other embodiments, InGaN active layer 420 can have a thickness of about O.lnm to 300nm, or about lnm to 50nm.
  • AlGaInN barrier layer 410 can have a thickness of several nanometers to several hundreds nanometers (nm). Alternatively, AlGaInN barrier layer 410 has a thickness of about O.lnm to 500nm or about lnm and to lOOnm. In other embodiments, a M-V group compound semiconductor material having a band gap wider than a band gap of a M-V group compound semiconductor material of the active layer can be selected fro the barrier layer.
  • InGaN active layer 420 has a smaller band gap than the band gap of AlGaInN barrier layer 410, thus forming a quantum well in InGaN active layer 420.
  • the band gap of InGaN active layer 420 is in the range of about 0.7eV and 3.4 eV
  • the band gap of AlInGaN barrier layer 410 is in the range of about 0.7eV and 6.3 eV.
  • the difference between the band gaps of InGaN active layer 420 and AlGaInN barrier layer 410 can be controlled by adjusting the composition of InGaN active layer 420, the composition of AlInGaN barrier layer 410, or the compositions of both InGaN active layer 420 and AlInGaN barrier layer 410.
  • aluminum (Al) composition of AlInGaN barrier layer 410 can be controlled so that AlInGaN barrier layer 410 has a larger band gap than that of InGaN active layer 420.
  • the composition of AlInGaN barrier layer 410 can be controlled to achieve a mole fraction of Al composition in the range of about 0.05 to 0.3, assuming that the total mole value of a M group compound, that is, Al, In and Ga is one.
  • an internal polarization field in a quantum well can be reduced by controlling the mole fractions of the compositions of InGaN active layer 420 and AlInGaN barrier layer 410, which will now be described in detail.
  • the graph shown in FIG. 5 illustrates the internal polarization field (y-axis) depending on the mole fraction of indium (In) composition (x-axis) of AlGaInN barrier layer 410.
  • InGaN active layer 420 is composed of In 0 iGaogN and has the thickness of 3nm.
  • AlGaInN barrier layer 410 is composed of Al 0 iGa O 9 - y In y N and has the thickness of about 3nm to 15nm.
  • Variable y which indicates the mole fraction of indium (In) composition of Al 0 iGao 9 _ y In y N barrier layer 410, may be controlled such that the sum P PZ w + P SP W of the piezoelectric and spontaneous polarizations in InGaN active layer 420 and the sum P PZ b + P SP b of the piezoelectric and spontaneous polarizations in AlGaInN barrier layer 410 are substantially the same.
  • the cancellation of the sum of piezoelectric and spontaneous polarizations between a quantum well and AlGaInN barrier layer 410 makes a total internal polarization field in InGaN active layer 420 zero as defined in Equation (6).
  • the solid line indicates the sum (P PZ W + P SP W ) of the piezoelectric and spontaneous polarizations in the quantum well.
  • the dotted or dashed line indicates the sum (P PZ b + P SP b ) of the piezoelectric and spontaneous polarizations inAlGalnN barrier layer 410.
  • An experimental test showed that the solid line meets the dotted line when indium (In) composition (y) of Al 0 ! Ga 09 ⁇ M y N barrier layer 410 has a mole fraction of approximately 0.16.
  • the internal polarization field in InGaN active layer 420 becomes approximately zero according to Equation (6). Accordingly, when variable y is approximately 0.16, that is, AlGaInN barrier layer 410 has the composition of Al 0 1 Ga 074 In 0 16 N, the internal polarization field becomes approximately zero. Through the minimization of the internal polarization field, quasi-Fermi separation can be largely enhanced and the optical gain g( ⁇ ) of semiconductor device 400 can be maximized in accordance with enhancement of quasi-Fermi separation, as illustrated above with respect to Equations (1).
  • Compositions of InGaN active layer 420 and AlGaInN barrier layer 410 can be controlled.
  • the graph shown in FIG. 6 illustrates the relationship between In composition of InGaN active layer 420 (having the thickness of 3nm) and In composition of AlGaInN barrier layer 410 (having the thickness of about 3nm to 15nm) when the internal polarization field is zero.
  • an x-axis indicates the mole fraction of In composition of InGaN active layer 420
  • y-axis indicates the mole fraction of In composition of AlGaInN barrier layer 410
  • the linear line indicates the points where the internal polarization field has a zero value.
  • the internal polarization field can be approximately zero when In compositions (variable x and y) of InGaN active layer 420 and AlGaInN barrier layer 410 are approximately 0.05 and 0.11 respectively (black square (a) on the linear line).
  • InGaN active layer 420 has the composition of In 005 Ga 095 N
  • AlGaInN barrier layer 410 has the composition of Al 0 1 Ga 079 In 0 nN.
  • semiconductor device 400 has In 0 1 Ga 09 N active layer and Al 0 1 Ga 074 In 0 16 N barrier layer, and the internal polarization field becomes approximately zero. Still further, at the black square (c) on the linear line (that is, x and y are approximately 0.15 and 0.21, respectively), semiconductor device 400 has In 0 15 Ga 085 N active layer and Al o 1 Ga 069 In 02I N barrier layer, and the internal polarization field becomes approximately zero.
  • In composition (y) of AlGaInN barrier layer 410 and/or In composition (x) of InGaN active layer 420 can be selected.
  • In composition (x) of In x Ga 1 ⁇ N active layer 420 can be in the range of about zero (0) and 0.3
  • In composition (y) of Al 0 ! Ga 09 ⁇ M y N barrier layer 410 can be in the range of about 0.01 and 0.3.
  • In composition (x) of In x Ga 1 ⁇ N active layer 420 is in the range of about 0.05 and 0.15, and In composition (y) of Al 0 !
  • Ga 09 ⁇ M y N barrier layer 410 can be in the range of about 0.1 and 0.22.
  • In composition (x) of In x Ga 1 ⁇ N active layer 420 is in the range of about 0.05 and 0.15
  • In composition (y) of Al 01 Ga 09 _ y In y N barrier layer 410 can be in the range of about 0.1 and 0.22.
  • the mole fractions of Al, Ga and In compositions of AlGaInN barrier layer 410 can be controlled to accomplish zero internal polarization field.
  • AlGaInN barrier layer 410 can have a composition of Al y iGai. y i. y2 ln y2 N (0 ⁇ yl+y2 ⁇ l).
  • Variables yl and y2 denote the mole fractions of Al and In compositions, respectively.
  • a subtraction of yl and y2 from one, that is, l-yl-y2 denotes the mole fraction of Ga composition of Al yl Ga 1 . y1 . y2 ln y2 N barrier layer 410.
  • yl can be in the range of about 0.05 to 0.3
  • y2 can be in the range of about 0.1 and 0.22, in order to accomplish the zero internal polarization field.
  • the relationship between III-V group compound semiconductor materials of an active layer and a barrier layer can show non-linear relationship, such as logarithmic or exponential relationship in accordance with the type of the III-V group compound semiconductor materials of the active layer and barrier layer and the variety of compositions of the III-V group compound semiconductor materials.
  • the mole fractions of In compositions of InGaN active layer 420 and AlGaInN barrier layer 410 can be selected in consideration of the compressive strain of InGaN active and AnGaInN barrier layers 420 and 410. Since the higher In composition (e.g., about 0.3 or more) of InGaN active layer 420 results in larger compressive strain and the growth of the strained layers is limited to a critical thickness, the lower In composition (e.g., about 0.01 to 0.1) can be selected.
  • the quasi-Fermi level separation increases, that is, the difference between the Fermi functions for the conduction band and valence band, i.e., (f c - f h ⁇ ), increases. Accordingly, by controlling the compositions of an active layer and/or a barrier layer to reduce the internal po- larization field, the quasi-Fermi level separation can be increased, and thus the optical gain g( ⁇ ) can be enhanced.
  • the graph shown in FIG. 7 illustrates the quasi-Fermi level separation (y-axis) for
  • InGaN/ AlGaInN semiconductor device 400 as a function of In composition of InGaN active layer (x-axis) 420.
  • the quasi-Fermi level separation decreases as In composition of AlGaInN barrier layer 410 increases.
  • the total quasi-Fermi level separation is 0.15 when the mole fraction of In composition is 0.05.
  • the quasi-Fermi level separation is 0.14 when the mole fraction of In composition is 0.15. Accordingly, it can be known that when In composition of AlGaInN barrier layer 410 is low, the quasi-Fermi level separation is high, thus the optical gain is high according to Equation (1).
  • the change of the optical gain for different In compositions of AlGaInN barrier layer 410 is shown in FIG. 8.
  • the graph shown in FIG. 8 illustrates a peak optical gain (y-axis) of InGaN/ AlGaInN semiconductor device 400 as a function of In composition of InGaN active layer (x-axis) 420.
  • the carrier density in InGaN active layer 420 (N 2D ) i.e. the number of carriers in InGaN active layer 420 per a square meter, is 20*10 12 cm 2 .
  • the peak optical gain increases as In composition of AlGaInN barrier layer 410 decreases.
  • the peak optical gain is approximately 12,600/cm when the mole fraction of In composition of InGaN active layer 420 is 0.05.
  • the peak optical gain is approximately 10,000/cm when the mole fraction is 0.15. Accordingly, the optical gain can be enhanced by controlling the composition of InGaN active layer 420.
  • a scattering rate in a quantum well decreases as an internal polarization field in the quantum well decreases. Accordingly, by reducing the internal polarization field, the scattering rate can be decreased, and thus the relaxation time can be decreased. This results in the enhancement of the optical gain.
  • the change of the scattering rate for different values of internal polarization field is illustrated in FIG. 9.
  • InGaN active layer 420 as a function of E t /h ⁇ q (x-axis) for different values of an internal polarization field F in InGaN active layer 420.
  • solid lines indicate when internal polarization field F is 200k V/F and dotted lines indicate when internal polarization field F is Ok V/F.
  • E t is a transition energy level
  • fi is the Plank constant
  • ⁇ q is a phonon angular frequency.
  • the scattering rate is low for both holes and electrons.
  • the low scattering rate results in a short relaxation time, and thus a high optical gain.
  • optical dipole matrix element in the quantum well increases as the internal polarization field decreases. Accordingly, by reducing the internal polarization field, the optical dipole matrix element can be increased and, thus, optical gain g( ⁇ ) can be enhanced.
  • the change of the optical dipole matrix for different compositions of the barrier layer is illustrated in FIG. 10.
  • the graph shown in FIG. 10 illustrates a normalized optical matrix element (y-axis) for InGaN/ AlGai_ y In y N semiconductor device 400 as a function (x-axis) of in-plane vectors for several In compositions of AlGa 1 ⁇ In 51 N barrier layer 410.
  • the carrier density (N 2D ) in active layer 420 i.e. the number of carriers in active layer 420 per a square meter, is about 20*10 12 cnr 2 .
  • the normalized optical matrix element is changed in accordance with In composition of AlGa 1 ⁇ In 51 N barrier layer 410.
  • this graph shows that the normalized optical matrix element for InGaNZAlGa 1 _ y In y N is enhanced as In composition (y) of AlGa 1 ⁇ In 5 N barrier layer 410 becomes smaller.
  • the normalized optical matrix element can be enhanced by controlling the composition of the barrier layer (e.g., In composition of AlGa 1 ⁇ In 51 N barrier layer 410).
  • the graph shown in FIG. 11 illustrates an optical gain (y-axis) of In x Ga 1 ⁇ NZAlGaInN semiconductor device 400 and a In x Ga 1 ⁇ NZGaN semiconductor device as a function (x-axis) of wavelength.
  • variable x is 0.05
  • the peak optical gain of In 05 Ga 05 NZAlGaInN semiconductor device 400 is approximately 13,000Zcm and the peak optical gain of the In 05 Ga 05 NZGaN semiconductor device is approximately 9,000Zcm.
  • the peak wavelength is shifted to shorter wavelength with the quaternary barrier layer.
  • InGaNZAlGaInN semiconductor device 400 has much larger optical gain than that of the InGaNZGaN semiconductor device due to disappearance of the internal field.
  • a semiconductor device may have II- VI group compound.
  • FIG. 12 is a schematic diagram of an illustrative embodiment of a II- VI group compound semiconductor device.
  • FIG. 13 is a graph showing an internal polarization field as a function of Mg composition of the MgZnO barrier layer for different Cd compositions of the CdZnO active layer depicted in FIG. 12.
  • FIG. 14 shows graphs illustrating (a) the relationship between Mg composition of the MgZnO barrier layer and Cd composition of the CdZnO active layer depicted in FIG. 12 and (b) a wavelength of the semiconductor device as a function of Cd composition of the CdZnO active layer depicted in FIG. 12.
  • FIG. 12 is a schematic diagram of an illustrative embodiment of a II- VI group compound semiconductor device.
  • FIG. 13 is a graph showing an internal polarization field as a function of Mg composition of the MgZnO barrier layer for different Cd compositions of the CdZnO active layer depicted in FIG. 12.
  • FIG. 14
  • a II- VI group compound semiconductor device 500 includes CdZnO active layer 520 (i.e. an active layer composed of CdZnO) and upper and lower MgZnO barrier layers 510 and 530 (i.e. upper and lower barrier layers each composed of MgZnO) disposed on opposite surfaces (e.g., top and bottom surfaces) of CdZnO active layer 520.
  • CdZnO active layer 520 i.e. an active layer composed of CdZnO
  • MgZnO barrier layers 510 and 530 i.e. upper and lower barrier layers each composed of MgZnO
  • II- VI group compound semiconductor device 500 may have either upper or lower MgZnO barrier layer 510 or 530 disposed on one side (e.g. top surface or bottom surface) of active layer 520.
  • CdZnO active layer 520 is composed of a II- VI group compound semiconductor material, for example, ZnO, ZnS, CdO, CdS, CdZnO, CdZnS, MgZnO, MgZnS, CdMgZnO or CdMgZnS.
  • CdZnO active layer 520 may have a thickness of several nanometers to several hundreds nanometers. In other embodiments, the thickness of CdZnO active layer 520 may be about 0. lnm to 300nm, or about lnm to 50nm.
  • upper and lower MgZnO barrier layers 510 and 530 each have a thickness of several nanometers to several hundreds nanometers. In other embodiments, upper and lower MgZnO barrier layers 510 and 530 may each have a thickness of about 0. lnm to 500nm or about lnm and to lOOnm.
  • the II- VI group compound semiconductor material of the upper and lower barrier layers e.g., upper and lower MgZnO barrier layers 510 and 530
  • a II- VI group compound semiconductor material having a wider band gap than that of a II- VI group semiconductor material of the active layer can be selected for the upper an lower barrier layers.
  • CdZnO active layer 520 has a band gap of about 2.2 eV to
  • upper and lower MgZnO barrier layers 510 and 530 each have a band gap of about 3.35 eV to 5.3 eV.
  • the band gaps of upper and lower MgZnO barrier layers 510 and 530 and CdZnO active layer 520 can vary depending on the compositions of Mg, Zn or Cd.
  • a quantum well is formed in CdZnO active layer 520.
  • the internal polarization field in the quantum well can be reduced by controlling the mole fractions of the compositions of CdZnO active layer 520 and upper and lower MgZnO barrier layers 510 and 530.
  • CdZnO active layer 520 has a composition of Cd x Zni_ x O (O ⁇ x ⁇ l) and a thickness of about 3nm
  • upper and lower MgZnO barrier layers 510 and 530 have the composition of Mg 5 Zn 1 ⁇ O (O ⁇ y ⁇ l) and have the thickness of about 3nm to 15nm.
  • III- V group compound semiconductor 400 with respect to FIG.
  • compositions of Cd x Zn 1 x O active layer 520 and upper and lower Mg 5 Zn 1 ⁇ O barrier layers 510 and 530 can be controlled to make the internal polarization field in CdZnO active layer 520 approximately zero.
  • II- VI group compound semiconductor device 500 has active/barrier layers of Cd 02 Zn 08 O/Mg 0 7 Zn 03 ⁇ .
  • Cd composition (x) of Cd x Zni_ x O active layer 520 is in the range of about zero (0) and 0.2
  • Mg composition (y) of Mg y Zni_ y O barrier layers 510 and 530 can be in the range of about 0.01 and 0.8.
  • Mg composition of upper and lower Mg y Zni_ y O barrier layers 510 and 530 can increase logarithmically in accordance with the increase of Cd composition of Cd x Zn 1 x O active layer 520 in the condition of zero internal polarization field.
  • Mg composition of upper and lower Mg 5 Zn 1 ⁇ O barrier layers 510 and 530 and Cd composition of Cd x Zn 1 x O active layer 520 are in a logarithmic relationship.
  • the relationship between II- VI group compound semiconductor materials of a barrier layer and an active layer at a zero internal polarization field can be inverse proportional or exponential depending on the type of the II- VI group compound semiconductor materials of the layers or various compositions of the II- VI group compound semiconductor materials.
  • a relationship between the II- VI group compound semiconductor materials of the barrier layer and the active layer at the zero internal polarization field can be linear depending on a type of the II- VI group compound semiconductor materials and compositions of the II- VI group compound semiconductor materials.
  • Graph (b) in FIG. 14 illustrates a transition wavelength of II- VI group compound semiconductor device 900 as a function of Cd composition of CdZnO active layer 520.
  • the transition wavelength of II- VI group compound semiconductor device 500 can be changed by controlling Cd composition of CdZnO active layer 520. Therefore, Cd composition is selected in accordance with a desirable transition wavelength for various optoelectronic devices. Further, Mg composition can be selected depending on the selected Cd composition to have substantially the zero internal polarization field in CdZnO active layer 520.
  • Graph (a) in FIG. 15 illustrates an optical gain (y-axis) of Cd x Zn 1 ⁇ OZMg 02 Zn 08 O semiconductor device for different Cd compositions, as a function of the transition wavelength (x-axis).
  • the optical gain is correlated to Cd composition. That is, the optical gain can be changed by controlling Cd composition of Cd x Zn 1 x O active layer 520. As Cd composition of Cd x Zn 1 x O active layer 520 changes, the optical gain and the transition wavelength varies.
  • the transition wavelength of II- VI group compound semiconductor device 500 is shifted to the left, that is, peak wavelength of II- VI group compound semiconductor device 500 is reduced, and the optical gain of II- VI group compound semiconductor device 500 increases.
  • the peak wavelength is approximately 0.385m and the optical gain in the peak wavelength is approximately 12,500/cm.
  • the peak of the transition wavelength of II- VI group compound semiconductor device 500 is approximately 0.375 and the optical gain of II- VI group compound semiconductor device 500 is approximately 20,000/cm. Accordingly, the optical gain of II- VI group compound semiconductor device 500 can be enhanced by controlling the mole fraction of Cd composition of Cd x Zn 1 x O active layer 520.
  • Graph (b) in FIG. 15 illustrates a peak gain (y-axis) Of Cd x Zn 1 ⁇ OZMg 02 Zn 08 O semiconductor device as a function of Cd composition (x-axis) of Cd x Zn 1 x O active layer 520.
  • a thickness of Cd x Zn 1 x O active layer 520 is about 3nm
  • a carrier density (N 2D ) in Cd x Zn 1 x O active layer 520 i.e.
  • II- VI group compound semiconductor device 500 can have the optical gain of approximately more than 17,000/cm when the mole fraction of Cd composition of Cd x Zn 1 x O active layer 520 is approximately 0.07.
  • a semiconductor device may have I- VII group compound.
  • I- VII group compound semiconductor device will be described with reference to FIG. 16.
  • FIG. 16 is a schematic diagram of an illustrative embodiment of a I- VII group compound semiconductor device.
  • a I- VII group compound semiconductor device 600 includes a CuBrF active layer 620 (i.e., an active layer composed of CuBrF) and a CuIBrCl barrier layer 610 (i.e., a barrier layer composed of CuIBrCl) disposed on one surface (e.g. a top surface) of CuBrF active layer 620.
  • I- VII group compound semiconductor device 600 may further have at least one additional barrier layers formed under one surface (e.g. a bottom surface) of CuBrF active layer 620.
  • CuBrF active layer 620 may have a thickness of several nanometers to several hundreds nanometers (nm). In other embodiments, CuBrF active layer 620 may have a thickness of f about 0.1 nm to 300nm, or about lnm to 50nm.
  • CuIBrCl barrier layer 610 may have a thickness of several nanometers to several hundreds nanometers (nm). In other embodiments, CuIBrCl barrier layer 610 may have a thickness of about 0. lnm to 500nm or about lnm and to lOOnm. In some embodiments, a I- VII group compound semiconductor material having a band gap wider than a band gap of a I- VII group compound semiconductor material of the active layer can be selected for the barrier layer.
  • CuBrF active layer 620 has a smaller band gap than the band gap of CuIBrCl barrier layer 610, thus forming a quantum well in CuBrF active layer 620.
  • the band gap of CuBrF active layer 620 is in the range of about 0.7eV and 3.4eV
  • the band gap of CuIBrCl barrier layer 610 is in the range of about 0.7eV and 6.3eV.
  • the difference between the band gaps of CuBrF active layer 620 and CuIBrCl barrier layer 610 can be controlled by adjusting the composition of CuBrF active layer 620, the composition of CuIBrCl barrier layer 610, or the compositions of both CuBrF active layer 620 and CuIBrCl barrier layer 610.
  • iodine (I) composition of CuIBrCl barrier layer 610 can be controlled so that CuIBrCl barrier layer 610 has a larger band gap than that of CuBrF active layer 620.
  • the composition of CuIBrCl barrier layer 610 can be controlled to achieve a mole fraction of I composition in the range of about 0.05 to 0.3, assuming that the total mole value of V group compound, that is the sum of mole fractions of I, Br and Cl, is one.
  • the internal polarization field in the quantum well formed in CuBrF active layer 620 can be reduced by controlling the mole fractions of the compositions of CuBrF active layer 620 and CuIBrCl barrier layer 610.
  • CuBrF active layer 620 is composed of CuBr 0 15 F 085 and has a thickness of 3nm.
  • CuIBrCl barrier layer 610 is composed of CuI 02 Br 08 - y Cl y and has a thickness of about 3nm to 15nm.
  • Variable y which indicates the mole fraction of a chlorine (Cl) composition of CuI 02 Br 08 _ y Cl y barrier layer 610.
  • Variable y is in the range of about 0 and 0.8, and is controlled such that the sum P PZ W + P SP W of piezoelectric and spontaneous polarizations in CuBrF active layer 620 and the sum P PZ b + P SP b of piezoelectric and spontaneous polarizations in CuIBrCl barrier layer 610 are substantially the same.
  • the cancellation of the sum of piezoelectric and spontaneous polarizations between the quantum well and CuIBrCl barrier layer 610 makes a total internal po- larization field in CuBrF active layer 620 substantially zero as illustrated with reference to Equation (6) above.
  • the mole fractions of I, Br and Cl compositions of CuIBrCl barrier layer 610 can be controlled to accomplish zero internal polarization field.
  • CuIBrCl barrier layer 610 can have a composition of CuI y1 Br 1 ⁇ y2 CI y2 (0 ⁇ yl+y2 ⁇ l).
  • Variables yl and y2 denote the mole fractions of I and Cl compositions, respectively.
  • the subtraction of the sum of yl and y2 from one (1), that is, l-yl-y2 denotes the mole fraction of Br composition of CuIBrCl barrier layer 610.
  • variable yl can be in the range of about 0.01 and 0.4
  • variable y2 can be in the range of about 0.2 and 0.35, in order to reduce the internal polarization field or accomplish the zero internal polarization field.
  • the composition control can be performed for CuBrF active layer 620.
  • the mole fractions of I, Br and Cl compositions of CuIBrCl barrier layer 610 are fixed to a certain number, the mole fractions of Br and F compositions of CuBrF active layer 620 can be adjusted to accomplish the zero internal polarization field.
  • CuBrF active layer 620 is composed of CuBr x F 1 ⁇ (O ⁇ x ⁇ l).
  • Variable x indicates the mole fraction of Br composition, and the subtraction of x from one (1), i.e. 1-x, indicates the mole fraction of F composition of CuBrF active layer 620.
  • Variable x can be adjusted to reduce the internal polarization field in CuBrF active layer 620 or accomplish the zero internal polarization field in CuBrF active layer 620.
  • variable x can be in the range of about 0.03 and 1.
  • variable x can be selected to be one (1).
  • active layer 620 is composed of CuBr.
  • CuBr has an excitonic binding energy of about 108meV which is much larger than that of ZnO. Accordingly, by selecting one as a value of x, active layer 620 can have a large excitonic binding energy and thus semiconductor device 600 can have a high optical gain.
  • the composition control can be performed for both CuBrF active layer 620 and CuIBrCl barrier layer 610.
  • CuBrF active layer 620 can have a composition of CuBr x F 1 ⁇ (O ⁇ x ⁇ l) and CuIBrCl barrier layer 610 can have a composition of (0 ⁇ yl+y2 ⁇ l).
  • variable x indicates the mole fraction of Br composition of CuBrF active layer 620
  • variables yl and y2 indicates the mole fractions of I and Cl compositions of CuIBrCl barrier layer 610, respectively.
  • Variables x, yl and y2 can be adjusted to reduce the internal polarization field in CuBrF active layer 620 or accomplish substantially the zero internal polarization field in CuBrF active layer 620.
  • variables x, yl and y2 can be in the ranges of about 0.03 and 0.5, about 0.01 to 0.4, and about 0.2 and 0.35, respectively.
  • FIGS. 17(a)-(e) are schematic diagrams illustrating an illustrative embodiment of a method for fabricating a semiconductor device 700.
  • a substrate 710 is provided.
  • Substrate 710 may be composed of a C-face (0001) or A-face (1120) oriented sapphire (Al 2 O 3 ).
  • substrate 710 may include silicon (Si), silicon carbide (SiC), spinel (MgA12O4), aluminum nitride (AlN), gallium nitride (GaN), or aluminum gallium nitride (AlGaN) without limitation.
  • a buffer layer 720 can be optionally disposed on one surface (e.g. a top surface) of substrate 710.
  • Buffer layer 720 can be made of a III- V group compound semiconductor material, a II- VI group compound semiconductor material, or a I- VII group compound semiconductor material.
  • the material for buffer layer 720 is not limited to aforementioned III- V, II- VI, and I- VII groups, but may also include any material that establishes good structural quality.
  • Buffer layer 720 can have a thickness of from about 0.1 ⁇ m to 300/M.
  • a lower barrier layer 730 may be disposed on a top surface of buffer layer 720, as depicted in FIG. 7(b).
  • Lower barrier layer 730 can include a M-V group compound semiconductor material, a II- VI group compound semiconductor material, or a I- VII group compound semiconductor material. Suitable materials and thickness for lower barrier layer 730 are substantially the same as the materials and thickness described above for lower barrier layer 110.
  • Lower barrier layer 730 can be formed by using any deposition techniques known in the art, such as radio-frequency (RF) magnetron sputtering, pulsed laser deposition, metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy, and radio-frequency plasma-excited molecular beam epitaxy, without limitation.
  • the composition of lower barrier layer 730 can be adjusted by controlling an amount of precursor gases provided to a deposition device (e.g. MOCVD) or by controlling a processing temperature or processing time.
  • an active layer 740 is disposed over lower barrier layer 730.
  • Active layer 740 can include a M-V group compound semiconductor material, a II- VI group compound semiconductor material, or a I- VII group compound semiconductor material. Suitable materials and thickness for active layer 740 are substantially the same as the materials and thickness described above for active layer 120. Active layer 740 can be formed by using any of the aforementioned deposition techniques known in the art.
  • an upper barrier layer 750 can be disposed on a top surface of active layer 730, as depicted in FIG. 17(d).
  • Upper barrier layer 750 can be composed of the same material as lower barrier layer 730.
  • upper barrier layer 750 can include a III- V group compound semiconductor material, a II- VI group compound semiconductor material or a I- VII group compound semiconductor material. Suitable materials and thickness for upper barrier layer 750 are substantially the same as the materials and thickness described above for lower barrier layer 110.
  • Upper barrier layer 750 can be formed by using any of the aforementioned deposition techniques known in the art.
  • lower barrier layer 730 or upper barrier layer 750 can be selectively disposed on active layer 730.
  • semiconductor device 700 can have lower barrier layer 730 disposed on a bottom surface of active layer 740, upper barrier layer 750 disposed on a top surface of active layer 740, or both lower and upper barrier layers 730 and 750 disposed on bottom and top surfaces of active layer 740, respectively.
  • the III- V group compound semiconductor materials, the II- VI group compound semiconductor materials, or the I- VII group compound semiconductor materials for active layer 740 and/or upper and lower barrier layers 750 and 730 can be selected such that active layer 740 has a narrower band gap than that of upper and lower barrier layers 750 and 730. This band gap difference forms a quantum well in active layer 740.
  • Electrode 760 can be optionally disposed on a top surface of upper barrier layer 750.
  • Electrode 760 can include conductive material such as an n-type doped semiconductor material, a p-type doped semiconductor material, or a metal.
  • Electrode 760 can include, without limitation, Al, Ti, Ni, Au, Ti/ Al, Ni/ Au, Ti/Al/Ti/Au, or an alloy thereof.
  • Electrode 760 can be formed to have a thickness of about lnm to 300nm, or about 5nm to 50nm.
  • Electrode 760 may be formed by using any techniques known in the art, such as sputtering, electroplating, e- beam evaporation, thermal evaporation, laser-induced evaporation, and ion-beam induced evaporation, without limitation.
  • a semiconductor device e.g., semiconductor device 700 fabricated according to the illustrated method can reduce internal polarization field in a quantum well by forming one or more barrier layers (e.g., upper barrier layer 750 and lower barrier layer 730) of a M-V group, a II- VI group, or a I- VII group compound material on an active layer (e.g., active layer 740) of a M-V group, a II- VI group, or a I- VII group compound material.
  • barrier layers e.g., upper barrier layer 750 and lower barrier layer 730
  • an active layer e.g., active layer 740
  • the semiconductor device can reduce the internal polarization field in the quantum well by controlling the mole fractions of a II- VI group compound material, a M-V group compound material, or I- VII group compound material in the active layer (e.g., active layer 740) or the one or more barrier layers (e.g., upper barrier layer 750 and lower barrier layer 730).
  • the optical gain of the semiconductor device e.g., semiconductor device 700
  • a photo-electric conversion device an optoelectronic device, a quantized electronic device, a short wavelength emitter, a photo detector, a laser, a high electron mobility transistor, or a light emitting device in which the semiconductor device (e.g. semiconductor devices 100, 400, 500, 600, and 700) described above is installed can be provided.
  • the semiconductor device e.g. semiconductor devices 100, 400, 500, 600, and 700
  • a range includes each individual member.
  • a group having 1-3 cells refers to groups having 1, 2, or 3 cells.
  • a group having 1-5 cells refers to groups having 1, 2, 3, 4, or 5 cells, and so forth.

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Abstract

L'invention porte sur des dispositifs à semi-conducteurs qui présentent au moins une couche barrière avec une large bande d'énergie interdite. Dans certains modes de réalisation, un dispositif à semi-conducteurs comprend au moins une couche active composée d'un premier composé, et au moins une couche barrière composée d'un second composé et agencée sur au moins une surface de la ou des couches actives. La ou les couches barrières peuvent avoir une bande d'énergie interdite plus large qu'une bande d'énergie interdite de la ou des couches actives. Il est possible d'agir sur les compositions des premier et second composés pour réduire un champ de polarisation interne dans la ou les couches actives.
PCT/KR2010/002655 2009-04-27 2010-04-27 Dispositif à semi-conducteurs WO2010126290A1 (fr)

Applications Claiming Priority (8)

Application Number Priority Date Filing Date Title
US12/430,424 2009-04-27
US12/430,406 US20100270592A1 (en) 2009-04-27 2009-04-27 Semiconductor device
US12/430,406 2009-04-27
US12/430,424 US20100270547A1 (en) 2009-04-27 2009-04-27 Semiconductor device
US12/431,930 2009-04-29
US12/431,921 2009-04-29
US12/431,921 US20100276730A1 (en) 2009-04-29 2009-04-29 Semiconductor device
US12/431,930 US8253145B2 (en) 2009-04-29 2009-04-29 Semiconductor device having strong excitonic binding

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WO2010126290A1 true WO2010126290A1 (fr) 2010-11-04

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Publication number Priority date Publication date Assignee Title
US4987462A (en) * 1987-01-06 1991-01-22 Texas Instruments Incorporated Power MISFET
US20020185655A1 (en) * 2000-07-18 2002-12-12 Fahimulla Ayub M. Ultra-linear multi-channel field effect transistor
US20030119223A1 (en) * 2001-12-26 2003-06-26 Jong-In Song Method for manufacturing msm photodetector using a hemt structure incorporating a low-temperature grown semiconductor
KR20040047132A (ko) * 2002-11-29 2004-06-05 (주)옵트로닉스 다중 양자우물 구조를 갖는 질화물 반도체 소자
KR20050010017A (ko) * 2002-05-30 2005-01-26 크리 인코포레이티드 비도핑 클래드층 및 다중 양자 우물을 가진 제ｉｉｉ족질화물 ｌｅｄ
KR20050029124A (ko) * 2002-06-04 2005-03-24 나이트라이드 세마이컨덕터스 코포레이션, 리미티드 질화 갈륨계 화합물 반도체 장치 및 제조방법
US20080001173A1 (en) * 2006-06-23 2008-01-03 International Business Machines Corporation BURIED CHANNEL MOSFET USING III-V COMPOUND SEMICONDUCTORS AND HIGH k GATE DIELECTRICS
KR20090053550A (ko) * 2007-11-23 2009-05-27 삼성전기주식회사 4원계 질화물 반도체 발광 소자 및 그 제조 방법

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4987462A (en) * 1987-01-06 1991-01-22 Texas Instruments Incorporated Power MISFET
US20020185655A1 (en) * 2000-07-18 2002-12-12 Fahimulla Ayub M. Ultra-linear multi-channel field effect transistor
US20030119223A1 (en) * 2001-12-26 2003-06-26 Jong-In Song Method for manufacturing msm photodetector using a hemt structure incorporating a low-temperature grown semiconductor
KR20050010017A (ko) * 2002-05-30 2005-01-26 크리 인코포레이티드 비도핑 클래드층 및 다중 양자 우물을 가진 제ｉｉｉ족질화물 ｌｅｄ
KR20050029124A (ko) * 2002-06-04 2005-03-24 나이트라이드 세마이컨덕터스 코포레이션, 리미티드 질화 갈륨계 화합물 반도체 장치 및 제조방법
KR20040047132A (ko) * 2002-11-29 2004-06-05 (주)옵트로닉스 다중 양자우물 구조를 갖는 질화물 반도체 소자
US20080001173A1 (en) * 2006-06-23 2008-01-03 International Business Machines Corporation BURIED CHANNEL MOSFET USING III-V COMPOUND SEMICONDUCTORS AND HIGH k GATE DIELECTRICS
KR20090053550A (ko) * 2007-11-23 2009-05-27 삼성전기주식회사 4원계 질화물 반도체 발광 소자 및 그 제조 방법

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