Interface intermixing and interdiffusion characteristics in MOVPE grown spontaneous Al x Ga 1-x As/GaAs (100) superlattice structures using high resolution X-ray diffraction

A. Pradhan, S. Mukherjee, T. Maitra, A. Nayak, S. Bhunia

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Thermal diffusion characteristics in naturally grown ultra-nanoscale superlattice structures have been studied. In absence of any suitable direct experimental tool due to the physical resolution limit, here we rely on the theoretical analysis of x-ray rocking curve simulations coupled with the diffusion equation to arrive at the diffusion characteristics across the interfaces of spontaneously grown Al x Ga 1-x As/Al y Ga 1-y As superlattice structures. The simulation approach presented here is a combination of a virtual interdiffusion code and a code on x-ray diffraction. We have obtained the variation in the actual diffusion coefficient as a function of time at different temperatures from the decay rates of the integrated satellite peak intensities. We have also found the diffusion coefficient to be highly nonlinear across the interface with time. The satellite decay equation could fit the experimental data taking the maximum Al composition alone at each time step. The pre exponential factor and the activation enthalpy values for interdiffusion are found out to be 0.17–0.25 cm 2 /s and 0.5–0.6 eV for Al diffusion whereas 0.01–0.11 cm 2 /s and 3.45–3.5 eV for Ga diffusion, respectively in the studied temperature range of 500 °C–700 °C. The interdiffusivity increases with temperature from 500 °C to 625 °C and decreases for further rise in temperature as the compositional contrast between the two layers decreases significantly at higher temperatures.

Original languageEnglish
Pages (from-to)193-199
Number of pages7
JournalSuperlattices and Microstructures
Volume126
DOIs
StatePublished - 1 Feb 2019
Externally publishedYes

Keywords

  • Al Ga As
  • HTXRD
  • Interdiffusion
  • MOVPE
  • Spontaneous superlattice

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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