scholarly journals Epitaxial Growth of GaP/InxGa1-xP (xIn ≥ 0.27) Virtual Substrate for Optoelectronic Applications

2011 ◽  
Vol 62 (2) ◽  
pp. 93-98 ◽  
Author(s):  
Stanislav Hasenöhrl ◽  
Jozef Novák ◽  
Ivo Vávra ◽  
Ján Šoltýs ◽  
Michal Kučera ◽  
...  
Keyword(s):  
Band Gap ◽  
Epitaxial Growth ◽  
Buffer Layer ◽  
Growth Parameters ◽  
Light Emitting Diode ◽  
Lattice Parameter ◽  
Buffer Layers ◽  
Light Emitting ◽  
Optoelectronic Applications ◽  
Band Gap Structure

Epitaxial Growth of GaP/InxGa1-xP (xIn ≥ 0.27) Virtual Substrate for Optoelectronic Applications Compositionally graded epitaxial semiconductor buffer layers are prepared with the aim of using them as a virtual substrate for following growth of heterostructures with the lattice parameter different from that of the substrates available on market (GaAs, GaP, InP or InAs). In this paper we report on the preparation of the step graded InxGa1-xP buffer layers on the GaP substrate. The final InxGa1-xP composition xIn was chosen to be at least 0.27. At this composition the InxGa1-xP band-gap structure converts from the indirect to the direct one and the material of such composition is suitable for application in light emitting diode structures. Our task was to design a set of layers with graded composition (graded buffer layer) and to optimize growth parameters with the aim to prepare strain relaxed template of quality suitable for the subsequent epitaxial growth.

Sn-based Group-IV Semiconductors on Si: New Infrared Materials and New Templates for Mismatched Epitaxy

2005 ◽  
Vol 891 ◽  
Author(s):  
John Tolle ◽  
Radek Roucka ◽  
Vijay D'Costa ◽  
Jose Menendez ◽  
Andrew Chizmeshya ◽  
...  
Keyword(s):  
Band Gap ◽  
Buffer Layer ◽  
Lattice Mismatch ◽  
Group Iv ◽  
Buffer Layers ◽  
Direct Band Gap ◽  
Group Iv Semiconductors ◽  
Direct Band ◽  
Infrared Materials ◽  
Edge Dislocations

ABSTRACTWe report growth and properties of GeSn and SiGeSn alloys on Si (100). These materials are prepared using a novel CVD approach based on reactions of Si-Ge hydrides and SnD4. High quality GeSn films with Sn contents up to 20%, and strain free microstructures have been obtained. The lattice mismatch between the films and Si is relieved by Lomer edge dislocations located at the interface. This material is of interest due to the predicted cross-over to a direct gap semiconductor for moderate Sn concentrations. We find that the direct band gap, and, consequently, the main absorption edge, shifts monotonically to lower energies as the Sn concentration is increased. The compositional dependence of the direct band gap shows a strong bowing, such that the direct band gap is reduced to 0.4 eV (from 0.8 eV for pure Ge) for a concentration of 14% Sn. The ternary SiGeSn alloy has been grown for the first time on GeSn buffer layers. This material opens up entirely new opportunities for strain and band gap engineering using group-IV materials via decoupling of strain and composition. Our SiGeSn layers have lattice constants above and below that of pure Ge, and depending on the thickness and composition of the underlying buffer layer they can be grown relaxed, with compressive, or with tensile strain. In addition to acting as a buffer layer for the growth of SiGeSn, we have found that GeSn can act as a template for the subsequent growth of a variety of materials, including III-V semiconductors.

Photocatalytic Degradation of Indigo Carmine Dye Using Hydrothermally Synthesized Anatase TiO2 Nanotubes under Ultraviolet Light Emitting Diode Irradiation

2016 ◽  
Vol 855 ◽  
pp. 45-57 ◽  
Author(s):  
Kalithasan Natarajan ◽  
Rukshana I. Kureshy ◽  
Hari C. Bajaj ◽  
Rajesh J. Tayade
Keyword(s):  
Photocatalytic Degradation ◽  
Band Gap ◽  
Organic Dyes ◽  
Light Emitting Diode ◽  
Indigo Carmine ◽  
Order Kinetic ◽  
Light Emitting ◽  
Order Kinetic Model ◽  
Different Temperatures ◽  
Adsorption Desorption

Anatase TiO2 nanotubes (ATNT) was synthesised by hydrothermal method using anatase TiO2 nanoparticles (AT) as precursor and calcined at two different temperatures (250 & 450 °C) for 2 h. The AT and synthesized ATNT photocatalysts were characterized by X-ray diffraction, transmission electron microscopy, N2 adsorption-desorption measurements, UV-vis diffuse reflectance and Fourier Transform Infra-red spectroscopy techniques for their structural, textural and electronic properties. The photocatalytic degradation of Indigo carmine (IC) dye aqueous solution has carried out using ATNT-250 and ATNT-450 photocatalysts under UVLED irradiation. The kinetic analysis has also revealed that the degradation of IC dye solution follows first order kinetic model. The overall study demonstrates the appropriate band gap of the photocatalysts used and the suitable irradiation source which could accelerate the rate of photocatalytic degradation. The band gap of the synthesised ATNT is not much affected due to the change in morphology from nanoparticle to nanotube. The results demonstrated that the irradiation of UV-LED could be utilised for the degradation of organic dyes

Improved MOCVD Growth of GaAs on Si

1987 ◽  
Vol 91 ◽  
Author(s):  
R.M. Lum ◽  
J.K. Klingert ◽  
B.A. Davidson ◽  
M.G. Lamont
Keyword(s):  
Buffer Layer ◽  
Rutherford Backscattering Spectrometry ◽  
Growth Parameters ◽  
Buffer Layers ◽  
Double Crystal ◽  
Gaas On Si ◽  
Mocvd Growth ◽  
Gaas Films ◽  
Gaas Buffer Layer ◽  
Direct Growth

ABSTRACTIn the direct growth of GaAs on Si by MOCVD the overall quality of the heteroepitaxial film is controlled to a large extent by the growth parameters of the initial GaAs buffer layer. We have investigated the structural properties of this layer using Rutherford Backscattering Spectrometry (RBS) and X-ray double crystal diffractometry. The crystallinity of the buffer layer was observed to improve with increasing layer thickness in the range 10–100nm, and then to rapidly degrade for thicker layers. High temperature (750°C) annealing of the buffer layers resulted in considerable reordering of all but the thicker (>200 nm) layers. Alteration of the usual GaAs/Si growth sequence to include an in-situ anneal of the buffer layer after growth interruption yielded GaAs films with improved structural, optical and electrical properties.

Dependence of the Residual Strain in GaN on the AlN Buffer Layer Annealing Parameters

1997 ◽  
Vol 468 ◽  
Author(s):  
Y.-M. Le Vaillant ◽  
S. Ciur ◽  
A. Andenet ◽  
O. Briot ◽  
B. Gil ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Annealing Time ◽  
Residual Strain ◽  
Lattice Mismatch ◽  
Strain Relaxation ◽  
Amorphous State ◽  
Lattice Parameter ◽  
Optical Quality ◽  
Buffer Layers ◽  
Aln Buffer

ABSTRACTThe problem of residual strain in GaN epilayers is currently the attention of many studies, since it affects the optical and electrical properties of the epilayers. In order to discuss the origin of this residual strain, we have grown a series of GaN epilayers onto AlN buffer layers, sapphire (0001) being used as substrate. The buffer layer is usually deposited in an amorphous state and is recrystallized by a thermal annealing. Here we have made a systematic study of the buffer recrystallization by changing the annealing temperature and the annealing time. The surface morphology is probed using Atomic Force Microscopy (AFM). The lattice parameter c is carried out from accurate x-ray diffraction measurements. The GaN layers were studied by low temperature photoluminescence and reflectivity. The amount of residual strain is calibrated from the position of the A exciton and the optical quality of the layers is assessed from the photoluminescence linewidths. The longer the annealing time the better the strain relaxation in AlN buffer layers and the higher the lattice mismatch with GaN overlayers.

High-efficiency vertical-structure GaN-based light-emitting diodes on Si substrates

2018 ◽  
Vol 6 (7) ◽  
pp. 1642-1650 ◽  
Author(s):  
Wenliang Wang ◽  
Yunhao Lin ◽  
Yuan Li ◽  
Xiaochan Li ◽  
Liegen Huang ◽  
...  
Keyword(s):  
High Efficiency ◽  
Light Emitting Diode ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Buffer Layers ◽  
Organic Chemical ◽  
Light Emitting ◽  
Si Substrates ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition

High-quality GaN-based light-emitting diode (LED) wafers have been grown on Si substrates by metal–organic chemical vapor deposition by designing epitaxial structures with AlN/Al0.24Ga0.76N buffer layers and a three-dimensional (3D) GaN layer.

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