Determination of the chemical composition of distorted InGaN/GaN heterostructures from x-ray diffraction data

Abstract

An evaluation algorithm for the determination of the chemical composition of strained hexagonal epitaxial films is presented. This algorithm is able to separate the influence of strain and composition on the lattice parameters measured by x-ray diffraction. The measurement of symmetric and asymmetric reflections delivers the strained lattice parameters a and c of hexagonal epitaxial films. These lattice parameters are used to calculate the relaxed lattice parameters employing the theory of elasticity. From the relaxed parameters, the chemical composition of the epitaxial film can be determined by Vegard's rule. The algorithm has been applied to InGaN/GaN/Al2O3(00.1) heterostructures.

Analysis of the Mosaic Defects in Graded and Non Graded In_xGa_1-xN Solar Cell Structures

“…This value is higher than the value determined previously (0.7 eV) [18]. There is an ongoing discussion about the forbidden energy band range of this layer although a lower forbidden energy band range was stated for InN.…”

Compositional dependence of the strain-free optical band gap in InxGa1−xN layers

“…In order to separate the influence of strain and composition effects on c InGaN , both lattice parameters a InGaN and c InGaN , have to be measured. 21 Therefore applying Hooke's law, x can be determined solving:…”

Enabling area-selective potential-energy engineering in InGaN/GaN quantum wells by post-growth intermixing

“…The shift towards the GaN peak indicated a lattice constant closer to that of GaN, i.e. a decrease in the out-of-plane compressive strain (along c-direction) due to a reduction in In mole-fraction in the QWs [25]. We observed stronger InGaN satellite peaks after RRTA and a reduction of FWHM of InGaN peak from 0.180° (as-grown) to 0.150° (intermixed) after intermixing, indicating improved crystal structures [26].…”

“…As for the non-intermixed LED, the peak EQE dropped to 0. 25 , corresponding to the SRH and Auger recombination process respectively. As the SRH recombination rate is proportional to n, while the Auger recombination rate is proportional to n 3 , the non-radiative recombination process is expected to be dominated by SRH recombination under low injection conditions and by Auger recombination at high injection currents.…”