Simulation of capacitance-voltage characteristics of heterostructures with quantum wells using a self-consistent solution of the Schrödinger and Poisson equations

Methods are developed for calculating capacitance-voltage characteristics and finding the concentration profile of free charge carriers in semiconductor doped heterostructures containing a quantum well. The capacitance-voltage characteristic of a heterostructure with a quantum well was calculated using a numerical self-consistent solution of the Poisson and Schrödinger equations in the context of a unified quantum-mechanical approach. The suggested method was applied to the simulation and analysis of the experimental capacitance-voltage characteristics of heterostructures with strained InGaAs/GaAs quantum wells.     

Current-injection efficiency in semiconductor lasers with a waveguide based on quantum wells

A dynamic distributed diffusion-drift model of laser heterostructures, which takes into account carrier capture by quantum wells, is developed. The leakage currents in the lasing mode are calculated for different laser structures without wide-gap emitters: InGaAs/GaAs (lasing wavelength λ = 0.98 μm), InGaAsP/InP (λ = 1.3 μm), and InGaAs/InP (λ = 1.55 μm). It is shown that consideration of the finite carrier-capture time is of major importance for calculating structures with deep quantum wells. The ratio of the leakage currents to the total current in the structures with deep quantum wells (InGaAsP/InP and InGaAs/InP) increases with an increase in the injection current and may reach a few percent when the lasing threshold is multiply exceeded.     

Stimulated emission in heterostructures with double InGaAs/GaAsSb/GaAs quantum wells,grown on GaAs and Ge/Si(001) substrates

We report the observation of stimulated emission in heterostructures with double InGaAs/GaAsSb/GaAs quantum wells, grown on Si(001) substrates with the application of a relaxed Ge buffer layer. Stimulated emission is observed at 77 K under pulsed optical pumping at a wavelength of 1.11 μm, i.e., in the transparency range of bulk silicon. In similar InGaAs/GaAsSb/GaAs structures grown on GaAs substrates, room-temperature stimulated emission is observed at 1.17 μm. The results obtained are promising for integration of the structures into silicon-based optoelectronics.     

Infrared reflection spectra of multilayer epitaxial heterostructures with embedded InAs and GaAs layers

The effect of the thickness of embedded InAs and GaAs layers on the infrared reflection spectra of lattice vibrations for AlInAs/InAs/AlInAs, InGaAs/GaAs/InGaAs, and AlInAs/InGaAs/GaAs/InGaAs/AlInAs multilayer epitaxial heterostructures grown by MOC hydride epitaxy on InP (100) substrates is studied. Relative stresses emerging in the layers surrounding the embedded layers with variation in the number of monolayers from which the quantum dots are formed and with variation the thickness of the layers themselves surrounding the embedded layers are evaluated.     

On the delta-type doping of GaAs-based heterostructures with manganese compounds

Heterostructures, which incorporate GaAs/InGaAs/GaAs quantum wells and are doped with spatially remote monatomic Mn layers, are formed on GaAs(001) substrate under conditions of multilayer buildup by the method of molecular-beam epitaxy. Combined studies of the obtained samples were performed by the method of secondary-ion mass spectrometry, by measurements of X-ray diffraction, and using a transmission electron microscope. The heterostructures under study with a doping impurity concentration amounting to 0.5 single layers are elastically stressed and demonstrate planar clearly defined interfaces without visible extended or point defects. A method for visualization of the distribution of the manganese concentration in the three-dimensional GaAs matrix in the vicinity of a quantum well is suggested. According to experimental results, there is a probability for manganese diffusion into the GaAs/InGaAs/GaAs quantum well when the critical thickness of the GaAs buffer layer is decreased to a value smaller than 3 nm.     

Spectral-kinetic properties of heterostructures with GaAsSb/InGaAs/GaAs-based quantum wells emitting in the range of 1.0–1.2 μm

The spectral-kinetic properties of heterostructures with GaAs/GaAsSb-based and GaAsSb/InGaAs/GaAs-based quantum wells, emitting in the range of 1.0–1.2 μm are studied with picosecond and nanosecond temporal resolution. Intense photoluminescence in the GaAsSb/InGaAs/GaAs structure, as well as an increase in the photoluminescence wavelength by a factor of 2.5 and a shift of the location of the maximum of the peak (～100 meV) to the longer-wavelength region were observed up to room temperature. It is established that as the molar fraction of Sb and the thickness of the InGaAs layer increase, the energy of the fundamental transition decreases by a factor of 140 meV compared with the GaAsSb/InGaAs/GaAs structure with a lower Sb content and a smaller thickness of the InGaAs layer. At 300 K, the emission wavelength of such a structure was 1.18 μm. In addition, an increase in the thickness of the InGaAs layer led to an increase in the room-temperature photoluminescence intensity by a factor of 60, which is associated with a decrease in the energy of the fundamental state for electrons in the InGaAs layer and, consequently, to larger electron localization and smaller temperature quenching of photoluminescence.     

Capacitance-voltage study of heterostructures with InGaAs/GaAs quantum wells in the temperature range from 10 to 320 K

Heterostructures with single strained InGaAs/GaAs quantum wells have been studied by measuring the capacitance-voltage characteristics in a wide range of temperatures and test signal frequencies. Based on the analysis of experimental capacitance-voltage characteristics, a temperature shift of the peak in the apparent profile of a majority carrier’s concentration is revealed and a quantitative model of this phenomenon is proposed. The effect of incomplete impurity ionization on the experimentally found quantum well’s charge is determined. It is established by numerical simulation and fitting of capacitance-voltage characteristics that the conduction band’s discontinuity for heterostructures with strained In _x Ga_{1 − x} As/GaAs quantum wells (x = 0.225) remains constant and equal to 172 ± 10 meV at temperatures from 320 to 100 K.     

分子束外延生长InGaAs/GaAs异质结及其在独特场效应晶体管中的应用

用分子束外延技术生长了ＩｎＧａＡｓ／ＧａＡｓ异质结材料,并用ＨＡＬＬ效应法和电化学Ｃ－Ｖ分布研究其特性。讨论了ＩｎＧａＡｓ／ＧａＡｓ宜质结杨效应晶体管（ＨＦＥＴ）的优越性。和ＧａＡｓ ＭＥＳＦＥＴＳ或ＨＥＭＴ相比,由于ＨＦＥＴ没有Ａｌ组份,具有低温特性好,低噪声和高增益等特点。本文研究了具有ＩｎＧａＡｓ／ＧａＡｓ双沟道和独特掺杂分布的低噪声高增益ＨＦＥＴ。     

Influence of defect formation as a result of incorporation of a Mn δ layer on the photosensitiviy spectrum of InGaAs/GaAs quantum wells

The influence of defect formation upon the deposition of a Mn δ layer and a GaAs coating layer (with the use of laser evaporation) on the photosensitivity spectra of heterostructures with InGaAs/GaAs quantum wells located in the near-surface region has been studied.     

Surface photoabsorption monitoring of the growth of GaAs and InGaAs at 650°C by MOCVD

By monitoring the cyclic behavior of surface photoabsorption (SPA) reflectance changes during the growth of GaAs at 650°C and with sufficient H₂ purging time between the supply of trimethylgallium and AsH₃, we have been able to achieve controlled growth of GaAs down to a monolayer. Our results show, as confirmed by photoluminescence (PL) measurements, the possibility of growing highly accurate quantum well heterostructures by metalorganic chemical vapor deposition at conventional growth temperatures. We also present our PL measurements on the InGaAs single quantum wells grown at this temperature by monitoring the SPA signal.     

Optical properties of metamorphic GaAs/InAlGaAs/InGaAs heterostructures with InAs/InGaAs quantum wells,emitting light in the 1250–1400-nm spectral range

It is demonstrated that metamorphic GaAs/InAlGaAs/InGaAs heterostructures with InAs/InGaAs quantum wells, which emit light in the 1250–1400 nm spectral range, can be fabricated by molecular-beam epitaxy. The structural and optical properties of the heterostructures are studied by X-ray diffraction analysis, transmission electron microscopy, and the photoluminescence method. Comparative analysis of the integrated photoluminescence intensity of the heterostructures and a reference sample confirm the high efficiency of radiative recombination in the heterostructures. It is confirmed by transmission electron microscopy that dislocations do not penetrate into the active region of the metamorphic heterostructures, where the radiative recombination of carriers occurs.     

Control of emission wavelength for InGaAs/GaAs quantum wells and laser structures on their basis by means of proton irradiation

Features of controlling the wavelength of emission from laser heterostructures with strained InGaAs/GaAs quantum wells by irradiation with medium-energy (with the energy as high as 150 keV) protons are studied. It is established that irradiation with H⁺ ions and subsequent thermal annealing at a temperature of 700°C make it possible to decrease the wavelength of emission from quantum wells. As the dose of ions is increased from 10¹³ to 10¹⁶ cm⁻², the magnitude of change in the wavelength increases to 20 nm. Starting with a dose of 10¹⁵ cm⁻², a significant decrease in the intensity of emission is observed. The optimum dose of H⁺ ions (6 × 10¹⁴ cm⁻²) and annealing temperature (700°C) for modifying the InGaAs/GaAs/InGaP laser structures are determined; it is shown that, in this case, one can obtain a shift of ∼(8–10) nm for the wavelength of laser radiation with low losses in intensity with the quality of the surface of laser structures retained. The observed “blue” shift is caused by implantation-stimulated processes of intermixing of the In and Ga atoms at the InGaAs/GaAs interface.     

Methods of controlling the emission wavelength in InAs/GaAsN/InGaAsN heterostructures on GaAs substrates

Studies of the properties of InGaAsN compounds and methods of controlling the emission wavelength in InAs/GaAsN/InGaAsN heterostructures grown by molecular beam epitaxy on GaAs substrates are reviewed. The results for different types of heterostructures with quantum-size InGaAsN layers are presented. Among those are (1) traditional InGaAsN quantum wells in a GaAs matrix, (2) InAs quantum dots embedded in an (In)GaAsN layer, and (3) strain-compensated superlattices InAs/GaAsN/InGaAsN with quantum wells and quantum dots. The methods used in the study allow controllable variations in the emission wavelength over the telecommunication range from 1.3 to 1.76 μm at room temperature.     

Time-Resolved Photoluminescence in Heterostructures with InGaAs:Cr/GaAs Quantum Wells

Semiconductors - The results of studies of the time-resolved photoluminescence in semiconductor heterostructures containing two noninteracting InGaAs quantum wells in a GaAs matrix are reported....     

InGaAs/AlGaAs QWIP Heterostructures for Large-Format Focal Plane Arrays Photosensitive in the Spectral Range 3–5 μm

Photoelectric properties of different stressed InGaAs/AlGaAs heterostructures with quantum wells grown by the method of molecular beam epitaxy on GaAs substrates for mid-wavelength infrared largeformat photodetector arrays operating in the spectral range 3–5 μm have been investigated. It has been shown that the change in the composition of barrier layers leads to a significant shift of the photosensitivity spectra of such heterostructures.     

Effect of He+ ion irradiation on the photosensitivity spectra of In(Ga)As/GaAs quantum well and quantum dot heterostructures

The effect of He⁺ ion implantation on the photosensitivity spectra of InGaAs/GaAs quantum well and InAs/GaAs quantum dot heterostructures grown by metalorganic chemical vapor deposition (MOCVD) epitaxy is studied.     

Structural and optical properties of GaAs-based heterostructures with Ge and Ge/InGaAs quantum wells

GaAs-based heterostructures with Ge and Ge/InGaAs quantum wells are grown by laser-assisted sputtering. Structural and optical studies of the heterostructures are carried out. A broad photoluminescence line is observed in the wavelength range from 1300 to 1650 nm. The line corresponds to indirect transitions in the momentum space of the Ge quantum wells and to transitions between the In_0.28Ga_0.72As and Ge layers, indirect in coordinate space, but direct in momentum space.     

Formation and passivation of defects in heterostructures with strained GaAs/InGaAs quantum wells as a result of treatment in a hydrogen plasma

The effect of processing heterostructures with GaAs/InGaAs quantum wells in the hydrogen plasma of an rf glow discharge on the photoluminescence spectrum and capacitive photovoltage of these structures is investigated. It is shown that strained quantum-well heterolayers hinder the diffusion of hydrogen and defects into the bulk, which causes the spatial distributions of recombination-active and passivated hydrogenic defect-like complexes in heterostructures, and the processes that create them, to differ appreciably from the same processes in uniform layers. Fiz. Tekh. Poluprovodn. 32, 1089–1093 (September 1998)     

The sandwich InGaAs/GaAs quantum dot structure for IR photoelectric detectors

A new possibility for growing InAs/GaAs quantum dot heterostructures for infrared photoelectric detectors by metal-organic vapor-phase epitaxy is discussed. The specific features of the technological process are the prolonged time of growth of quantum dots and the alternation of the low-and high-temperature modes of overgrowing the quantum dots with GaAs barrier layers. During overgrowth, large-sized quantum dots are partially dissolved, and the secondary InGaAs quantum well is formed of the material of the dissolved large islands. In this case, a sandwich structure is formed. In this structure, quantum dots are arranged between two thin layers with an increased content of indium, namely, between the wetting InAs layer and the secondary InGaAs layer. The height of the quantum dots depends on the thickness of the GaAs layer grown at a comparatively low temperature. The structures exhibit intraband photoconductivity at a wavelength around 4.5 μm at temperatures up to 200 K. At 90 K, the photosensitivity is 0.5 A/W, and the detectivity is 3 × 10⁹ cm Hz^1/2W^?1.     

量子阱平面光学各向异性的偏振差分反射谱研究

在室温下用偏振差分反射谱技术观察到了 Ga As/Al Ga As、In Ga As/Ga As和 In Ga As/In P三种量子阱材料的平面光学各向异性。我们发现 Ga As/Al Ga As量子阱 1 h→ 1 e跃迁的偏振度与阱宽成反比 ,与 In Ga As/In P量子阱的报道结果类似。 Ga原子偏析引起的界面不对称可以很好地解释这种行为。与之相反 ,In Ga As/Ga As量子阱的光学各向异性倾向于与阱宽成正比。目前还不能很好地解释这种现象。