Photoluminescence study of interfaces between heavily doped Al0.48In0.52As:Si layers and InP (Fe) substrates (original) (raw)
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Journal of Applied Physics, 2002
Properties of the interface between the epitaxial layer of heavily doped Al 0.48 In 0.52 As:Si and the InP͑Fe͒ substrate are investigated by photoluminescence in AlInAs:Si/InP͑Fe͒ heteroestructures grown by molecular beam epitaxy. The effect on heterostructure optical properties of including a thin Al 0.22 Ga 0.26 In 0.52 As:Si layer at the interface is investigated as well. To explain the different interface emission energies observed, the results are analyzed by using the mixed-type I-II interface model, which considers in the type II interface a narrow InAs well, with variable width, between AlInAs and InP. The observation of the interface emission at energies as high as 1.36 eV, at low excitation intensity, is explained taking into account the high doping level of the samples. The observed interface transition luminescence thermal quenching is tentatively explained by analyzing the spatial distribution of electrons in the triangular quantum well formed at the type II interface ͑or at the mixed I-II interface͒ as a function of the temperature.
Journal of Applied Physics, 1999
A set of heavily doped Al0.48In0.52As samples grown by molecular beam epitaxy on InP (Fe) substrates was investigated using the photoreflectance (PR) technique. The spectra at 300 K are characterized by a transition in the vicinity of the InP energy gap, followed by strongly damped Franz-Keldysh oscillations (FKOs) which do not appear when the spectra are obtained at 77 K. The builtin electric field estimated from FKOs shows a small doping dependence but is substantially affected by the inclusion of a thin layer of AlxGayIn1-x-yAs (x≡0.22) at the interface between InP (Fe) and AlInAs:Si. In order to explain these results, a model based on the discontinuity of the energy bands in the InP/AlInAs and InP/AlGaInAs/AlInAs systems and also on the matching of the Fermi levels between the different materials is suggested.
Intense interface luminescence in type II narrow-gap InAs-based heterostructures at room temperature
Physics Procedia, 2010
Positive and negative luminescence was observed in a type II broken-gap p-InAs/p-GaAsSb heterostructure in the mid-infrared spectral range 3-5 m at room temperature. Interface-related radiative recombination was provided by Mn acceptor states on InAs surface. I-V characteristics behavior was discussed using the tunneling-assisted current transport mechanism through surface states. Redistribution between the interband (h 1 =0.36 eV) and interface (h 2 =0.31 eV) emission bands in electroluminescent spectra at reverse bias was found in dependence on Fermi level position pinning by surface states at the type II broken-gap heterointerface.
Journal of Applied Physics, 2018
A set of samples containing a single ultrathin InAs layer with varying thickness from 0.5 to 1.4ML in a GaAs matrix have been grown by molecular beam epitaxy on GaAs (001) substrates at low temperatures and investigated by low-temperature photoluminescence (PL). A linear change in emission energy with InAs thickness has been experimentally observed. The PL emission line shape from InAs/GaAs heterostructures has been investigated as a function of incident optical intensity. The interplay between uncorrelated electron-hole pairs, free excitons, and localized excitons, as a function of the excitation intensity, is found to play a significant role on the optical properties of the InAs layer and is described in detail.
Atomic layer diffusion and electronic structure at In0. 53Ga0. 47As/InP interfaces
We have used secondary ion mass spectrometry and cathodoluminescence spectroscopy to determine the effects that growth and postgrowth conditions have on interdiffusion and near band edge emissions in In 0.53 Ga 0.47 As/InP heterojunctions grown by molecular beam epitaxy. This lattice-matched interface represents a model system for the study of atomic movements and electronic changes with controlled anion overlap during growth. Structures subjected to anneals ranging from 440 to 495°C provide a quantitative measure of concentration-driven cross diffusion of group-III and group-V atoms. By measuring anneal-induced broadening at the InGaAs-on-InP interface we have determined an activation energy for As diffusion into InP of ϳ2.44Ϯ0.40 eV. An interface layer with Ga-P bonds indicates Ga competes favorably versus As for bonding in the preannealed InP near-surface region. In addition, we present evidence that interface chemical effects manifest themselves electronically as variations of the InGaAs band gap energy.
Growth and properties of In0.52Al0.48As/In0.53Ga0.47As, GaAS: In and InGaAs/GaAs multilayers
Journal of Crystal Growth, 1987
We have investigated the properties of some In-containing materials and heterostructures grown by molecular beam epitaxy on GaAs and InP substrates. Photoluminescence spectra of InGaAs/InAlAs quantum wells have been related to growth kinetics and it is seen that growth interruption or the incorporation of a few periods of superlattices at the heterointerfaces smooths the growth front. Experiments have been performed to determine the properties of In0 52A1048As grown on InP. This lattice-matched alloy In0 52Al048As may be clustered under normal growth conditions at a substrate temperature 500°C.Addition of small amounts of In (0.2-1.2%) to GaAs reduces trap and defect densities in these materials, as seen from DLTS and low-temperature photoluminescence data. The improvement may be related to the higher surface migration rate of In compared to Ga and a subsequent reduction of point defects. Single-mode optical guides and direction couplers with losses as low as 1-3 dB/cm have been fabricated with GaAs: In and In02Gao gAs/GaAs strained-layer superlattices.
Materials Science in Semiconductor Processing, 2019
Three types of GaAs/Al 0.30 Ga 0.70 As quantum wells (QWs) with InAs quantum dots (QDs) cavered by the different capping layers: GaAs (#1), Al 0.30 Ga 0.70 As (#2) and Al 0.1 Ga 0.75 In 0.15 As (#3), have been investigated. The photoluminescence (PL), its temperature dependence and high resolution X-ray diffraction (HR-XRD) methods were applied. It is revealed that QD emission in the structure #3 is characterized by the lower PL peak energy, highest PL intensity and smaller half widths of PL bands, in comparison with the QD emissions in #1 and #2. PL temperature dependences have been studied that revealing the QD material composition in #3 is closer to InAs than those in #1 and #2. HR-XRD scan fitting permits to understand the process of strain relaxation in studied structures at high QW growth temperatures. This process in the structures #1 and #2 was connected with material composition varying the QDs and capping layers due to Ga/In atom intermixing that leads to the QD emission shift into the higher energy range and PL intensity decreasing. Meanwhile in the structure #3 with Al 0.1 Ga 0.75 In 0.15 As capping, the strain relaxation manifests itself by InAs QD height decreasing without changing the InAs QD material composition. The advantages of Al 0.1 Ga 0.75 In 0.15 As capping layer used and its impact on the emission of InAs QDs have been discussed.
Truly ohmic contacts in engineered Al/Si/InGaAs(001) diodes
Applied Physics Letters, 1998
We report the fabrication of nonalloyed ohmic contacts on n-In x Ga 1Ϫx As (0.25рxр0.38) grown by molecular beam epitaxy ͑MBE͒ on GaAs͑001͒. This result is obtained by suppression of the native Al/InGaAs Schottky barrier by means of the MBE growth of Si bilayers at the metal-semiconductor interface. Truly ohmic contacts are demonstrated by x-ray photoemission spectroscopy and current-voltage techniques.
The Structure of Al/GaAs Interfaces
MRS Proceedings, 1986
ABSTRACTThe structure of Al/GaAs interfaces was investigated by high resolution electron microscopy. The Al layers Were deposited in a molecular beam epitaxy chamber with a vacuum base pressure of <1×10∼8 Pa. The GaAs substrate temperature varied during Al deposition from -30°C to 400°C. Deposition of Al on cold substrates £25°C resulted in epitaxial growth of (001) Al on (001) GaAs. Droplets of Ga were observed in samples with the substrate temperature at -30°C (1×2) and 0°C (c(2×8)). Postannealing of the last sample caused formation of the AlGaAs phase. Deposition of Al on hot substrates (150°C and 400°C) resulted in the formation of the AlGaAs phase, which separated (110) oriented Al from (001)GaAs.