Vibrational Characteristics of High-Quality MBE Grown GaAs1−x−ySbyNx/GaAs (001) Epilayers

TL;DR

This paper studies the vibrational properties of a quaternary semiconductor alloy to improve optoelectronic and photovoltaic technologies.

Contribution

The paper presents new experimental and theoretical insights into the lattice dynamics of GaAs1−x−ySbyNx/GaAs epilayers.

Findings

Raman measurements detected ωTO(Γ)GaAs and ωTO(Γ)GaAs phonons and a high-frequency NAs local mode near 476 cm−1.

Weak phonon structures suggest a complex NAs–Ga–SbAs defect center.

Simulations using a rigid-ion model confirmed the experimental data on impurity modes.

Abstract

The significant disparity between the size and electronegativity of N and group-V (P, As, Sb) atoms in dilute III–V-Ns remains a cornerstone for developing the next-generation electronics. Variations in the structural, optical, and phonon properties of the quaternary GaAs1−x−ySbyNx alloys are being used for improving the high-performance photovoltaic energy and optoelectronic technologies. Bandgap Eg tunability has assisted efficient light emission/detection to cover the crucial optical fiber wavelengths for the low-cost integrated chips in data communications and sensing devices. The lattice dynamical properties of these materials are critical for assessing the reliability to evaluate the performance of long-wavelength lasers, photodetectors, and multi-junction solar cells. Our systematic Raman measurements on high-quality MBE grown GaAs0.946Sb0.032N0.022/GaAs samples have detected ωTO(Γ)GaAs and ωTO(Γ)GaAs phonons along with a high frequency NAs local mode near ~476 cm−1. Weak phonon structures on both sides of the broad 476 cm−1 band are interpreted forming a complex NAs–Ga–SbAs defect center. Using a realistic rigid-ion model in the Green’s function framework, the simulations of impurity modes for isolated and complex defects have provided corroboration to the experimental data.

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