Interdiffusion in InGaAs/GaAs and InGaAs/GaAsP quantum wells (original) (raw)
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Applied Physics Letters, 1996
High structural and optical quality In x Ga 1Ϫx P/GaAs quantum wells, with x from 0.51 to 0.45, have been successfully grown by atomic layer molecular beam epitaxy. In that compositional range, an important blue shift of the quantum well luminescence lines is observed, which is explained by an increase of the conduction band gap offset from compressive to tensile strain conditions. The luminescence intensity decreases with temperature above 20-30 K, which is attributed to impurities located at the interfaces and inside the quantum wells. The influence of the In content on the oscillator strength of the optical transitions is also evaluated.
Physica E: Low-dimensional Systems and Nanostructures, 2003
Temperature dependence of the e ective band gap (BG) energy of strained InxGa1−xAs=GaAs single-quantum well and multi-quantum well structures grown by solid source MBE at varied substrate temperature is investigated by photoluminescence spectroscopy between 10 K and room temperature. For low-temperature-grown heterostructure, the temperature-induced BG shrinkage exhibits a good correlation with that of unstrained material. However, no consensus is shown to occur for a relatively high-temperature-grown quantum wells (QWs). This discrepancy is interpreted in terms of indium segregation and reevaporation during epitaxy. The low-temperature range, where the well-known Varshni law fails to ÿt PL peak positions, is found to decrease with increasing QW width and is attributed to the interface-roughness-induced exciton localization. This study was propped by numerical solving of Schr odinger equation taking into account strain, indium segregation and desorption e ects. ?
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1994
Thermal interdiffusion in five-period Si/Si, "Ge"superlattices with periods of 200 A and Ge concentrations between x =0.20 and 0.70 was studied using Rutherford backscattering spectrometry in grazing-angle geometry. Both asymmetrically strained superlattices grown directly on Si, as well as symmetrically strained superlattices grown on relaxed Si&~Ge~buffer layers, were grown to compare the inhuence of the strain distribution on the interdiffusion. Rapid thermal annealing in the temperature range between 900 and 1125'C leads to substantial interdiffusion indicated by a significant decrease of the amplitudes of the modulations of the backscattering yield. Interdiffusion coefficients were deduced using a Fourier algorithm. For a given Ge concentration x, the thermal dependence of the interdiffusion coefficients follows an Arrhenius law. The interdiffusivity increases with increasing Ge concentrations. An average activation energy for interdiffusion of-4.0 eV was obtained. The elastic strain and the formation of crystal defects due to thermal treatment were investigated by He ion channeling.
Applied Surface Science, 2004
Lattice-matched, single and multiple InGaP/GaAs/InGaP quantum wells (QWs) were grown at 600 8C by low-pressure metalorganic vapour phase epitaxy (LP-MOVPE), with the use of the tertiarybuthylarsine (TBAs) and tertiarybuthylphosphine (TBP) group-V sources. In order to enhance the interface abruptness, different gas switching sequences were exploited during the growth of the interface, and the best results were obtained by inserting a few monolayer-thick GaAsP interlayers (IL), at the direct GaAs-on-InGaP interface. Low-temperature photoluminescence (PL), high resolution X-ray diffraction, transmission electron microscopy and photoreflectance spectroscopy analysis were performed on the grown heterostructures, to correlate the adopted growth sequence with the interface properties and the QW optical transitions.
Journal of Materials Science: Materials in Electronics, 2017
[6] and tunneling diodes [7]. It was shown that the disadvantages of InAs/GaAs or InAs/InGaAs QD systems are connected with QD non-homogeneous surface distribution, significant dispersion of QD sizes or QD compositions that lead to the differences in optical device parameters [8-10]. Additional factor that has an impact on QD device parameters is the In/Ga atom inter-diffusion between the QDs and QWs. In/Ga intermixing can be realized on the different stages of QD and QW growth processes. A number of papers were published recently concerning the study of In/Ga intermixing at thermal annealing [11-13]. The main attention in these papers was connected with the spectral shift investigation for QD emission that was detected after thermal annealing. However the essentially more information concerning In/Ga intermixing between QDs and QW can be obtained at the joint investigation of QD emission and QW parameters using high-resolution X ray diffraction (HR-XRD) method [14, 15]. In present paper the emission and HR-XRD were studied in InGaAs/GaAs QW structures with embedded InAs QDs grown at different temperatures from the range 470-535 °C. 2 Experimental conditions InAs QD structures were grown by the molecular beam epitaxy (MBE) on the (001) semi-insulating GaAs substrates. Each structure includes a 200 nm GaAs buffer layer and a 100 nm GaAs upper final capping layer that were grown at 600 °C (Fig. 1). Between GaAs layers there are a second In 0.15 Ga 0.85 As buffer layer (2 nm), then the self-organized InAs QD array formed by the deposition of 2.4 ML of InAs, and first capping In 0.15 Ga 0.85 As layers (Fig. 1). Both the buffer and capping In 0.15 Ga 0.85 As layers were grown at 510 °C. The growth temperature of InAs QDs varies for Abstract GaAs/In 0.15 Ga 0.85 As/GaAs QWs with embedded InAs QDs grown at different temperatures have been studied by means of the photoluminescence (PL), X ray diffraction (XRD) and high resolution XRD (HR-XRD) methods. PL study has detected varying of QD parameters and HR-XRD permits monitoring the QW parameters. It is shown that increasing the QD growth temperature up to 510 °C leads to raising the QD sizes, to shift of QD emission peak to low energy and increasing the PL intensity of QDs. Simultaneously Ga/In atom intermixing is realized mainly between the InGaAs buffer and InAs wetting layers and did not influent on the InAs QD composition. At higher QD growth temperatures (525-535 °C) the PL intensity of QDs decreases significantly together with decreasing the QD heights and the shift of PL peaks into higher energy. Fitting the HR-XRD results has revealed that Ga/In atom intermixing involves the composition changes in buffer and wetting layers, as well as in QDs. The mentioned optical and structural effects have been discussed in details.
Applied Sciences, 2021
InGaAs quantum well (QW) lasers have attracted significant attention owing to their considerable potential for applications in optical communications; however, the relationship between the misorientation of the substrates used to grow InGaAs QWs and the structural and optical properties of QWs is still ambiguous. In this study, In-rich InGaAs/GaAsP single QWs were grown in the same run via metal organic chemical vapor deposition on GaAs (001) substrates misoriented by 0°, 2°, and 15° toward (111). The effects of substrate misorientation on the crystal quality and structural properties of InGaAs/GaAsP were investigated by X-ray diffraction and Raman spectroscopy. The 0° substrate exhibited the least lattice relaxation, and with increasing misorientation, the degree of lattice relaxation increased. The optical properties of the InGaAs/GaAsP QWs were investigated using temperature-dependent photoluminescence. An abnormal S-shaped variation of the peak energy and inverse evolution of th...
Enhancement of compositional disordering in strained InxGa1-xAs/GaAs quantum wells by Zn diffusion
Superlattices and Microstructures, 1991
We report the enhancement of InGa interdiffusion in strained InxGa1- x{As}/{GaAs} (x=0.20-0.24) single quantum well (QW) structures by surface Zn diffusion. The epitaxial structures were grown by MOVPE and consist of a 1-2μm thick GaAs buffer layer, followed by the In xGa 1-xAs QW with 80-100Å thickness and a GaAs cap layer 500-1000Å thick. We have performed various shallow Zn diffusion depths for times and temperatures ranging from 1.3 to 3.5min. and 585-620°C, respectively, in order to vary the Zn concentration in the QWs. The samples were then annealed between 650-785°C under {AsH3}/{H2} to determine the enhanced InGa interdiffusion coefficient and its activation energy. A model is proposed to explain the enhancement of interdiffusion by Zn diffusion which involves an interstitial migration process.
Thermal processing of strained-layer InGaAs/GaAs quantum well interface
Applied Surface Science, 1994
Thermal processing of strained-layer lnGaAs/GaAs quantum well interracial properties has been investigated. Room-temperature photoluminesccnce and X-ray diffraction are measured from as-grown and rapid thermal annealing (RTA) treated InGaAs/GaAs samples. It has been found that RTA improves photoluminesccnce intensity for the defect-rich samples, due to a removal of non-radiative recombination centers from the quantum well during RTA. Because of interdiffusion of Ga and In atoms during annealing, the InGaAs/GaAs interfaces grade and the quantum confined states shift upwards in energy. On the other hand, RTA degrades the structural quality of the InGaAs/GaAs quantum well if the annealing temperature is too high.
HigHighly strained InGaAs/GaAs quantum wells emitting beyond 1.2 µm
Crystal Research and Technology, 2005
Highly strained In x Ga 1-x As quantum wells (QWs) with GaAs barriers emitting around 1.2 µm are grown on GaAs substrates by metal organic vapour phase epitaxy (MOVPE) at low growth temperatures using conventional precursors. The effects of growth temperature, V/III ratio and growth rate on QW composition and luminescence properties are studied. The variation of indium incorporation with V/III ratio at a growth temperature of 510°C is found to be opposite to the results reported for 700°C. By an appropriate choice of the growth parameters, we could extend the room temperature photoluminescence (PL) wavelength of InGaAs/GaAs QWs up to about 1.24 µm which corresponds to an average indium content of 41% in the QW. The results of the growth study were applied to broad area laser diodes emitting at 1193 nm with low threshold current densities.