Structural and Optical Properties of InAsSbBi Grown by Molecular Beam Epitaxy on Offcut GaSb Substrates

Rajeev R Kosireddy,Shane R Johnson,Marko S Milosavljevic,Stephen T Schaefer

doi:10.3390/photonics8060215

Rajeev R Kosireddy, Shane R Johnson + Show 2 more

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https://doi.org/10.3390/photonics8060215

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Abstract

Three InAsSbBi samples are grown by molecular beam epitaxy at 400 °C on GaSb substrates with three different offcuts: (100) on-axis, (100) offcut 1° toward [011], and (100) offcut 4° toward [011]. The samples are investigated using X-ray diffraction, Nomarski optical microscopy, atomic force microscopy, transmission electron microscopy, and photoluminescence spectroscopy. The InAsSbBi layers are 210 nm thick, coherently strained, and show no observable defects. The substrate offcut is not observed to influence the structural and interface quality of the samples. Each sample exhibits small lateral variations in the Bi mole fraction, with the largest variation observed in the on-axis growth. Bismuth rich surface droplet features are observed on all samples. The surface droplets are isotropic on the on-axis sample and elongated along the [011¯] step edges on the 1° and 4° offcut samples. No significant change in optical quality with offcut angle is observed.

Highlights

High-speed, highly sensitive optoelectronic devices such as photodetectors and lasers operating in the mid- and long-wave infrared spectrum are desired for applications including navigation, night vision, missile detection, communication, imaging, and spectroscopy [1]
The Bi and Sb mole fractions are adjusted in the simulation to match the angular separation of the InAsSbBi layer and GaSb substrate peaks, uniquely identifying the InAsSbBi lattice constant
The thickness of the InAsSbBi layer and the AlSb barrier layers are adjusted in the simulation to match the period and spacing, respectively, of the Pendellösung fringes, which arise from thin film X-ray interference

Summary

Introduction

High-speed, highly sensitive optoelectronic devices such as photodetectors and lasers operating in the mid- and long-wave infrared spectrum are desired for applications including navigation, night vision, missile detection, communication, imaging, and spectroscopy [1]. The highly electronegative N atoms introduce an impurity energy level near the host conduction band, resulting in splitting of the conduction band and a decrease in the band gap energy due to the band anti-crossing interaction [7,8,9,10]. The smaller electronegativity of Bi results in an impurity energy level near the host material valence band and splitting of the valence band due to a similar band anti-crossing interaction [9,10,11,12,13,14]. The band anti-crossing interaction due to Bi incorporation results in strong spin-orbit splitting in the valence band [9,15]. The extra degree of design freedom afforded by the quaternary

Results

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Conclusion