Showing papers on "Heterojunction published in 1990"
TL;DR: In this article, it was shown that the properties of the deep level when resonant with the conduction band are similar to its characteristics when it is the stable state of the donor.
Abstract: D X centers, deep levels associated with donors in III‐V semiconductors, have been extensively studied, not only because of their peculiar and interesting properties, but also because an understanding of the physics of these deep levels is necessary in order to determine the usefulness of III‐V semiconductors for heterojunction device structures. Much progress has been made in our understanding of the electrical and optical characteristics of D X centers as well as their effects on the behavior of various device structures through systematic studies in alloys of various composition and with applied hydrostatic pressure. It is now generally believed that the D X level is a state of the isolated substitutional donor atom. The variation of the transport properties and capture and emission kinetics of the D X level with the conduction‐band structure is now well understood. It has been found that the properties of the deep level when it is resonant with the conduction band, and is thus a metastable state, are similar to its characteristics when it is the stable state of the donor. And it has been consistently found that there is a large energy difference between the optical and thermal ionization energies, implying that this deep state is strongly coupled to the crystal lattice. The shifts in the emission kinetics due to the variation in the local environment of the donor atom suggest that the lattice relaxation involves the motion of an atom (the donor or a neighboring atom) from the group‐III lattice site toward the interstitial site. Total energy calculations show that such a configuration is stable provided that the donor traps two electrons, i.e., has negative U. Verification of the charge state of the occupied D X level is needed as well as direct evidence for its microscopic structure.
673 citations
TL;DR: In this paper, the authors measured the conductance of GaAs and found that periodic oscillations correspond to the sequential addition of single electrons to the segment of the channel between the barriers.
Abstract: Narrow channels interrupted by two controlled potential barriers and having a tunable electron density were made in GaAs, and their conductance was measured at low temperatures. Reproducible and accurately periodic oscillations of the conductance with changing density are found to correspond to the sequential addition of single electrons to the segment of the channel between the barriers. Detailed examination of the line shape of the conductance versus density provides a new insight into the transport mechanism.
469 citations
TL;DR: In this article, a double-heterostructure indium-tin-oxide substrate/hole transport layer/emitter layer/electron transport layer was fabricated by vacuum vapor deposition.
Abstract: Organic electroluminescent devices with a double‐heterostructure indium‐tin‐oxide substrate/hole transport layer/emitter layer/electron transport layer/MgAg have been fabricated by vacuum vapor deposition. The organic carrier transport and emitter layers were composed of amorphous films. In the double‐heterostructure devices, the luminance continued to lie in high level, even when the emitter thickness was 50 A. The confinement of charge carriers and molecular excitons within a narrow emitter layer was achieved.
389 citations
TL;DR: In this paper, a tunable doping superlattice laser has been demonstrated, which has a potential tuning range of 220 A and is a candidate for an optical source in future optical communication systems.
Abstract: Delta‐function‐like doping profiles can be obtained in semiconductors by growth‐interrupted impurity deposition during molecular‐beam epitaxy. The spatial localization of dopants is assessed by the capacitance–voltage profiling technique and secondary ion mass spectroscopy which yield profile widths of 20 and 37 A for Be δ‐doped GaAs grown at 500 °C, respectively. The diffusion coefficients of Si, Be, and C in GaAs and of Si in AlxGa1−xAs are determined and diffusion is shown to be negligible at low growth temperatures. At elevated growth temperatures, dopant redistribution occurs during epitaxial growth. The redistribution is shown to be due to (i) diffusion of dopants and (ii) Fermi‐level pinning induced segregation of dopants along the growth axis. Fermi‐level pinning induced segregation of dopants is a novel mechanism which results in a redistribution of dopants predominantly toward the growing surface due to electrostatic attraction of dopants and carriers localized in surface states. This mechamism is shown to be relavant at elevated growth temperatures of ≥600 °C. Electronic devices such as homostructure and heterostructure field‐effect transistors which employ the δ‐doping technique have a number of advantages including (i) high carrier density, (ii) proximity between electron channel and gate electrode, (iii) large breakdown voltage of the gate, and (iv) reduced short‐channel effects. In addition, high transconductances are obtained in such δ‐doped field‐effect transistors. The optical properties of doping superlattices are significantly improved using the δ‐doping technique. Quantum‐confined interband transitions in doping superlattices are observed for the first time in such improved doping superlattices. Furthermore, a tunable doping superlattice laser is demonstrated, which has a tuning range of 35 A. The tunable doping superlattice laser has a potential tuning range of 220 A and is a candidate for a tunable source in future optical communication systems.
228 citations
TL;DR: A simple model demonstrates that the oscillations arise from the formation of a miniband structure in the periodic crystal, including energy gaps and minibands which contain fifteen discrete states.
Abstract: We have studied the magnetotransport properties of an artificial one-dimensional crystal. The crystal consists of a sequence of fifteen quantum dots, defined in the two-dimensional electron gas of a GaAs/AlGaAs heterostructure by means of a split-gate technique. At a fixed magnetic field of 2 T, two types of oscillations with different amplitude and period are observed in the conductance as a function of gate voltage. A simple model demonstrates that the oscillations arise from the formation of a miniband structure in the periodic crystal, including energy gaps and minibands which contain fifteen discrete states.
180 citations
TL;DR: In this article, a numerical model for heterojunctions is discussed in which current transport across the heterojunction interface is taken into account by using thermionic emission current in series with drift-diffusion current in the bulk.
Abstract: A numerical model for heterojunctions is discussed in which current transport across the heterojunction interface is taken into account by using thermionic emission current in series with drift-diffusion current in the bulk. The thermionic emission current is regarded as a boundary condition, which is used to obtain a relationship between quasi-Fermi-levels on both sides of the interface. GaAs-AlGaAs heterojunctions are simulated as an example, and the results are compared with those obtained by a conventional diffusion model in which current transport across the heterojunction interface is not considered explicitly. It is shown that the thermionic emission mechanism is important and should be considered, particularly in isotype heterojunctions. With the present model, more general numeral analyses that include thermionic emission, drift, and diffusion phenomena can be achieved. >
176 citations
TL;DR: In this paper, a review of the criteria that must be met for the fabrication of metal/III-V heterostructures is presented, highlighting the relationship between symmetry differences and defects.
165 citations
TL;DR: In this paper, a single quantum well diode InGaAs/AlGaAs single-well diode laser emitting at 1.02 μm has been fabricated from structures grown by organometallic vapor phase epitaxy.
Abstract: Graded‐index separate‐confinement heterostructure InGaAs/AlGaAs single quantum well diode lasers emitting at 1.02 μm have been fabricated from structures grown by organometallic vapor phase epitaxy. Under pulsed operation, threshold current densities as low as 65 A/cm2, the lowest reported for InGaAs/AsGaAs lasers, have been obtained for a cavity length L of 1500 μm. Differential quantum efficiencies as high as 90% have been obtained for L=300 μm. Output powers as high as 1.6 W per facet and power conversion efficiencies as high as 47% have been obtained for continuous operation of uncoated lasers with L=1000 μm.
155 citations
TL;DR: In this article, the conduction and valence-band offsets for GaAs/Ga0.51In0.49P quantum wells were independently estimated by measuring the capacitance transient resulting from thermal emission of carriers from the respective wells.
Abstract: We have independently estimated the conduction‐ and valence‐band offsets ΔEc and ΔEv in GaAs/Ga0.51In0.49P quantum wells by measuring the capacitance transient resulting from thermal emission of carriers from the respective wells. The heterostructure samples were grown by low‐pressure metalorganic chemical vapor deposition. The band offsets are extrapolated from the emission activation energies with appropriate corrections. The estimated values of ΔEc and ΔEv are 0.198 and 0.285 eV, respectively.
131 citations
TL;DR: In this paper, the critical thickness-strain relationship for buried strained layers and strained layer superlattices (SLSs) were derived using an energy balance model, and the extent of relaxation and detailed dislocation structure were assessed in annealed structures by x-ray rocking curve analysis, transmission electron microscopy, and Nomarski microscopy of etched samples.
Abstract: The critical thickness‐strain relationships for buried strained layers and strained‐layer superlattices (SLSs) are derived using an energy balance model. Relaxation of the entire heterostructure and individual strained layers by both 60° type a/2〈011〉 and pure edge dislocations is considered. GexSi1−x/Si heterostructures designed to investigate the stability regimes predicted by the model were grown by molecular‐beam epitaxy. The extent of relaxation and the detailed dislocation structure were assessed in annealed structures by x‐ray rocking curve analysis, transmission electron microscopy, and Nomarski microscopy of etched samples. Comparison of metastable as‐grown and post‐growth annealed microstructures revealed the evolution of misfit dislocation structure as equilibrium was approached on annealing in the temperature range 600–900 °C. The predominant relaxation mechanism for most GexSi1−x/Si heterostructures was by 60° a/2 〈011〉 misfit dislocations at the first strained‐layer/substrate interface. Howe...
124 citations
TL;DR: In this article, the authors reported the determination of Auger recombination coefficients in bulk and quantum well InGaAs by time-resolved luminescence measurements, and they found that the Auger coefficient decreases slightly with decreasing well width.
Abstract: We report the determination of Auger recombination coefficients in bulk and quantum well InGaAs by time‐resolved luminescence measurements. In bulk InGaAs the coefficient is C=3.2×10−28 cm6/s and has the temperature dependence of the valence‐band Auger effect involving the split‐off valence band. In 11 nm quantum well InGaAs we find C=0.9×10−28 cm6/s, independent of temperature. The Auger coefficient decreases slightly with decreasing well width.
TL;DR: In this article, photoreflectance-derived band-gap parameters as a function of temperature for InGaAs and InAlAs lattice matched to InP are reported, on a set of samples of various compositions (and strains) yielding greater reliability and ensuring self-consistency.
Abstract: Photoreflectance‐derived band‐gap parameters as a function of temperature for InGaAs and InAlAs lattice matched to InP are reported. The experiment was performed on a set of samples of various compositions (and strains) yielding greater reliability and ensuring self‐consistency. For InGaAs, fits to the Varshni equation gave E0(T=0 K)=803 meV, α=4.0×10−4 eV K−1, and β=226 K. For InAlAs, E0(T=0 K)=1.541 eV, α=4.7×10−4 eV K−1, β=149 K, and Δ0=338 meV.
TL;DR: In this article, a complete DC model for the heterojunction bipolar transistor (HBT) is presented, which is compared with the Ebers-Moll (EM) model used by conventional bipolar junction transistors (BJTs) and implemented in simulation and modeling programs.
Abstract: A complete DC model for the heterojunction bipolar transistor (HBT) is presented. The DC characteristics of the HBT are compared with the Ebers-Moll (EM) model used by conventional bipolar junction transistors (BJTs) and implemented in simulation and modeling programs. It is shown that although the details of HBT operation can differ markedly from those of a BJT, a model and a parameter extraction technique can be developed which have physical meaning and are exactly compatible with the EM models widely used for BJTs. Device I-V measurements at 77 and 300 K are used to analyze the HBT physical device performance in the context of an EM model. A technique is developed to extract the device base, emitter, and collector series resistances directly from the measured I-V data without requiring an ideal exp(qV/sub be//kT) base current as reference. Accuracies of the extracted series resistances are assessed. AC parameters of HBT are calculated numerically from the physical device structure. For modeling purposes, these parameters are shown to be comparable with those of conventional BJTs. >
TL;DR: In this article, the absolute amplitude of the low-field Shubnikov-de Haas oscillations was used to measure inter-subband scattering in 2D heterojunction structures.
Abstract: A new technique, using the absolute amplitude of the low-field Shubnikov-de Haas oscillations, is presented which allows the direct measurement of inter-subband scattering in 2D heterojunction structures. When applied to a heterojunction with two subbands occupied the technique is used to show that inter-subband scattering is independent of temperature between 1 and 4 K. In agreement with previous reports frequency and amplitude intermodulation, which increases with temperature, is also observed. This is attributed to mixing, by thermal or impurity damping, between the two sets of oscillations in the Fermi energy. This explanation is supported by a model calculation which reproduces the features of the experimental results.
TL;DR: In this paper, a Si-based infrared detector is proposed based on internal photoemission over a Si1−xGex/Si heterojunction barrier, which requires a degenerately doped p+−Si1−Gex layer for strong infrared absorption and photoresponse.
Abstract: A new approach to the design of a Si‐based infrared detector is demonstrated, based on internal photoemission over a Si1−xGex/Si heterojunction barrier. The heterojunction internal photoemission device structure is grown by molecular beam epitaxy (MBE). The detector requires a degenerately doped p+‐Si1−xGex layer for strong infrared absorption and photoresponse. Doping concentrations to 1020 cm−3 are achieved using boron from a HBO2 source during MBE growth of the Si1−xGex layers. The photoresponse of this device is tailorable, and most significantly, can be extended into the long‐wavelength infrared regime by varying the Ge ratio x in the Si1−xGex layers. Results are obtained with x=0.2, 0.28, 0.3, and 0.4 on patterned Si (100) substrates. Photoresponse at wavelengths ranging from 2 to 10 μm is obtained with quantum efficiencies above ∼1% in these nonoptimized structures.
TL;DR: Etude dans le cadre de la fonctionnelle de densite, dans l'approximation de la densite locale, en conjonction avec une geometrie du superreseau pour resoudre l'equation de Schrodinger de l'heterojonction.
Abstract: A theory of heterojunction band offsets is developed within the density-functional framework in the local-density approximation. The linear-muffin-tin-orbital method is used in conjunction with a superlattice geometry for solving Schr\"odinger's equation of the heterojunction. The potential is constructed within the atomic-sphere approximation. Within this context the long-range electrostatics reduce to that of point charges, and the average electrostatic potential of the latter can be used as a local reference level. It is shown that, starting from an arbitrary alignment of the bulk potentials, the correct potential alignment is obtained by minimizing the total energy with respect to a single parameter: the interface dipole. This minimization is equivalent to screening the initially induced dipole by the macroscopic dielectric constant of the interface region of the heterojunction, which can be identified approximately with the harmonic average of the dielectric constants of the two semiconductors. The conditions under which this is valid are discussed. The calculations are performed within a so-called frozen-shape approximation, allowing the potentials to vary only by constant shifts. Almost perfect agreement between calculations using a different shift per atomic layer and calculations using a single shift per semiconductor provide a numerical demonstration that the self-consistent dipole is independent of the details of the dipole profile. They also show that the macroscopic dielectric constant of the heterojunction in the vicinity of the interface can be obtained with reasonable accuracy from the single-parameter variational calculation itself. The calculations also show that linear response is valid over a wide range. The theory is applied to an extensive set of lattice-matched semiconductor (110) interfaces and shown to be in excellent agreement with experimental results and previous more-involved calculations where available. The consequences of the present theory for interface-orientation dependence and metal-semiconductor interfaces are briefly discussed.
TL;DR: The selective area epitaxy of GaInAs/InP layers grown by low-pressure metalorganic vapor phase epitaxy through SiO2 patterned masks was investigated in this paper, where the layers were found to develop mesa structures limited by {111} and (100) facets outside of the opened mask, and perfect selective epitaxy was obtained.
Abstract: The selective area epitaxy of GaInAs/InP layers grown by low‐pressure metalorganic vapor phase epitaxy through SiO2 patterned masks was investigated. The layers are found to develop mesa structures limited by {111} and (100) facets outside of the opened mask, and perfect selective epitaxy is obtained. The absence of GaInAs growth on {111} facets allows the fabrication of very narrow buried GaInAs layers in a single growth step. For both materials, the growth rates are found to depend strongly on the mask geometry owing to surface diffusion of the reactant species from the no‐ or low‐growth SiO2 mask and {111} facets toward (100) surfaces. A detailed quantitative analysis is made to identify the critical parameters that control the growth behavior, and a model is described from which the upper limit of the growth rates for any mask design can be calculated. Low‐temperature cathodoluminescence measurements show strong emission of the buried GaxIn1−xAs layers and indicate local stoichiometry variations Δx≂±5...
TL;DR: Mesure de la mobilite et des densites electroniques des sous-bandes individuelles de ces heterojonctions presentant deux occupations de sous -bandes en fonction de la densite du gaz d'electrons bidimensionnel.
Abstract: Mesure de la mobilite et des densites electroniques des sous-bandes individuelles de ces heterojonctions presentant deux occupations de sous-bandes en fonction de la densite du gaz d'electrons bidimensionnel. On fait varier la densite au moyen de la photoconductivite persistante en utilisant les rayonnements IR et rouge
TL;DR: In this article, a unified analytical charge control model covering the entire range of gate voltages from below and above threshold is developed for heterojunction field-effect transistors (HFETs).
Abstract: A unified analytical charge control model covering the entire range of gate voltages from below and above threshold is developed for heterojunction field-effect transistors (HFETs). This model is based on a new interpretation of the quantized energy levels for the two-dimensional electron gas. It reduces to a classical charge sheet model in the limit of low surface field. The model is used to interpret the experimental data for the subthreshold regime of HFETs. The results indicate wide range variation of the effective acceptor concentration after device fabrication processing in the unintentionally doped GaAs buffer layer. >
TL;DR: In this article, a new type of high-efficiency solar cell has been developed by a simple production process only with electron cyclotron resonance plasma assisted chemical vapor deposition of highly conductive microcrystalline silicon carbide (μ c ‐SiC) on polycrystaline silicon (poly-Si).
Abstract: A new type of high‐efficiency solar cell has been developed by a simple production process only with electron cyclotron resonance plasma‐assisted chemical vapor deposition of highly conductive microcrystalline silicon carbide (μ c ‐SiC) on polycrystalline silicon (poly‐Si). The device consists of a p ‐type μ c ‐SiC/ n ‐type poly‐Si heterojunction where the window material is a specially made wide‐band gap and highly conductive μ c ‐SiC. At the present stage, a conversion efficiency of 15.4% with V oc=556 mV, J sc=35.7 mA/cm2, and F. F.=77.4% has been achieved. Also employing this device as a bottom cell in a four‐terminal amorphous silicon ( a ‐Si) tandem‐type solar cell, 16.8% efficiency has been obtained. A series of technical data on the fabrication technology and device performance is presented and discussed.
TL;DR: The (111) double layer with the maximum number of Ge-Ge bonds is found to be energetically the most stable and to have the smallest dipole, but it is still large compared to typical band offsets in semiconductors.
Abstract: We have carried out ab initio self-consistent calculations to investigate the extent to which the band offset can be modified by polar layers. The cases studied are double layers of Ge in bulk GaAs (for which the offsets are totally due to induced dipoles) in (100) and two distinctly different (111) geometries. The (111) double layer with the maximum number of Ge-Ge bonds is found to be energetically the most stable and to have the smallest dipole, but it is still large (0.7 eV) compared to typical band offsets in semiconductors. We argue that this demonstrates the potential possibility of providing a mechanism for band-offset engineering using thin layers at interfaces.
TL;DR: In this article, a resonant cavity composed of an AlAs/GaAs buried mirror structure (reflectivity R = 0.9) and the epilayer surface (R= 0.3) was used to enhance the InGaAs absorption wavelength, an improvement of η from 6.7 to 43% was demonstrated, in agreement with calculations through the spectral analysis of the HPTs with and without resonant cavities.
Abstract: Gain and spectral response of heterojunction phototransistors (HPTs) having a thin (0.1 μm) InGaAs strained absorbing layer in the collector has been investigated. Low dark current ∼ 5 pA (1×10−8 A/cm2) and large optical gain as high as 500 were observed. A resonant cavity composed of an AlAs/GaAs buried mirror structure (reflectivity R=0.9) and the epilayer surface (R=0.3) was used to enhance the otherwise small quantum efficiency η (at InGaAs absorption wavelength). For a 1000 A absorbing layer an improvement of η from 6.7 to 43% (6.4‐fold) was demonstrated, in agreement with calculations, through the spectral analysis of the HPTs with and without resonant cavities.
TL;DR: In this article, a heterostructure system of Y1Ba2Cu3O7−y/Y1−xPrxBa2cu3O 7−y which maintains epitaxy over the entire Pr composition range x=0-1.
Abstract: For a variety of device applications, junction devices in particular, we have demonstrated a heterostructure system of Y1Ba2Cu3O7−y/Y1−xPrxBa2Cu3O7−y which maintains epitaxy over the entire Pr composition range x=0–1. We have grown both trilayer and multiperiod superlattices which show nearly single crystalline helium ion backscattering minimum yields of <6% in the topmost layer. X‐ray diffraction measurements indicate c‐axis orientation by a transverse scan across (005) line with a full width at half maximum of 0.6° and 0.4° on MgO and SrTiO3 substrates, respectively. Scanning Auger electron depth profiles and cross‐sectional transmission electron micrographs indicate abrupt Pr/Y interfaces within one unit cell and virtually no disruption of the layered structure at the interface. These results indicate the potential for the growth of excellent heterostructures and superlattices of the high‐temperature superconductors.
TL;DR: In this article, the interference of x-ray wave fields in semiconductor heterostructures can be used to detect ultrathin layers having 1 monolayer thickness, and the interference effect is studied experimentally by using a high-resolution double-crystal xray diffractometer.
Abstract: We show that the interference of x‐ray wave fields in semiconductor heterostructures can be used to detect ultrathin layers having 1 monolayer thickness. A detailed theoretical and experimental investigation on Si/Six Ge1−x heterostructures is presented. The interference effect is studied experimentally by using a high‐resolution double‐crystal x‐ray diffractometer. The diffraction patterns are recorded in symmetrical as well as asymmetrical Bragg geometries and are analyzed by using the dynamical x‐ray diffraction theory for distorted crystals.
Patent•
20 Sep 1990
TL;DR: In this paper, the growth of a quantum well active region that is highly lattice-mismatched relative to a substrate is considered and a buffer layer having a thickness above a critical value is grown on the substrate whereby the stress due to a lattice constant mismatch between the buffer layer and substrate is relieved through the formation of misfit dislocations.
Abstract: A method of fabricating a semiconductor heterostructure includes the growth of a quantum well active region that is highly lattice-mismatched relative to a substrate. A buffer layer having a thickness above a critical value is grown on the substrate whereby the stress due to a lattice constant mismatch between the buffer layer and substrate is relieved through the formation of misfit dislocations. A strained superlattice structure is grown on the buffer layer in order to terminate any upwardly-propagating dislocations. An unstrained barrier layer is subsequently grown on the superlattice structure. The fabrication method concludes with the growth of a quantum well structure on the unstrained layer wherein a lattice constant mismatch between the quantum well structure and the unstrained barrier layer is smaller than the lattice constant mismatch between the quantum well structure and the substrate. As a result, only a fraction of the stress due to the large lattice mismatch between the quantum well structure and the substrate is accommodated by coherent strain in the quantum well structure, while the remainder of the stress is relieved through the formation of misfit dislocations spatially separated from the quantum well structure.
TL;DR: In this article, a germanium-implanted layer was grown epitaxially in the solid phase by thermal annealing, and two kinds of crystalline defects were observed: a misfit dislocation and a residual dislocation caused by ion bombardment.
Abstract: Formation of SiGe/Si heterostructures by germanium ion implantation was investigated. A germanium‐implanted layer was grown epitaxially in the solid phase by thermal annealing. Two kinds of crystalline defects were observed. One is a misfit dislocation, and the other is a residual dislocation caused by ion bombardment. The p‐n junction formed in the SiGe layer has a leakage current three orders of magnitude larger than that of a pure Si p‐n junction fabricated with an identical process except for the Ge+ implantation. Carbon doping in the SiGe layer improves its crystalline quality and the junction characteristics.
TL;DR: In this article, a GaAs/AlGaAs Npn heterojunction bipolar transistor (HBT) was fabricated and characterized for dc current gain, emitter−base junction ideality factor, base contact resistance, and external base resistance.
Abstract: Carbon tetrachloride (CCl4) has been used as a carbon doping source for the base region of a GaAs/AlGaAs Npn heterojunction bipolar transistor (HBT) grown by low‐pressure metalorganic chemical vapor deposition (MOCVD). Transistors were fabricated and characterized for dc current gain, emitter‐base junction ideality factor, base contact resistance, and external base resistance. Microwave characterization by S‐parameter measurement was performed to determine the common emitter current gain and maximum available gain as a function of frequency. Transistors with the base contact area self‐aligned to a 3×10 μm emitter finger had a dc current gain as high as 50, an emitter‐base junction ideality factor of n=1.2, and a current gain cutoff frequency of ft=26 GHz. Transistors of equal emitter area without self‐alignment exhibited dc current gain as high as 86, n=1.2, and ft=20 GHz. A base contact resistance of Rc=2.85×10−6 Ω cm2 and an external base sheet resistance of Rs=533.4 Ω/⧠ were measured. These preliminary...
TL;DR: In this article, the long-term degradation of AlxGa1−xAs−AlAs (GaAs) quantum well heterostructure material due to the instability of underlying (internal) AlAs layers is studied.
Abstract: Data are presented on the long‐term (≳8 yr) degradation of AlxGa1−xAs‐AlAs ‐GaAs quantum well heterostructure material because of the instability of underlying (internal) AlAs layers. Material containing thicker (>0.4 μm) AlAs ‘‘buried’’ layers (confining layers) is found to be much less stable than material containing thinner (≲200 A) AlAs layers. Hydrolysis of the AlAs layers because of cleaved edges and pinholes in the cap layers leads to the deterioration.
TL;DR: In this article, thin films were prepared conveniently and reproducibly using the spray-pyrolysis technique, which enables the incorporation of foreign materials like indium in the matrix and the effect of In incorporation on the conductivity and optical properties of the prepared films was studied.
Abstract: thin films were prepared conveniently and reproducibly using the spray‐pyrolysis technique This method enables the incorporation of foreign materials like indium in the matrix The effect of In incorporation on the conductivity and optical properties of the prepared films was studied The presence of In in the bulk of the film increases its conductivity and does not affect the optical properties to a significant extent The energy gap of the prepared films was calculated for different layer thickness of pure and In‐incorporated films Heterojunction solar cells were prepared and investigated using a standard potentiostatic technique The power characteristics of the prepared photovoltaic cells were analyzed and compared with those of pure solar cells