Optical Characterization of AlAsSb Digital Alloy and Random Alloy on GaSb

Bor-Chau Juang,Diana Huffaker,Dingkun Ren,Arion Chatziioannou,David Prout,Baolai Liang

doi:10.3390/cryst7100313

Abstract

III-(As, Sb) alloys are building blocks for various advanced optoelectronic devices, but the growth of their ternary or quaternary materials are commonly limited by spontaneous formation of clusters and phase separations during alloying. Recently, digital alloy growth by molecular beam epitaxy has been widely adopted in preference to conventional random alloy growth because of the extra degree of control offered by the ordered alloying. In this article, we provide a comparative study of the optical characteristics of AlAsSb alloys grown lattice-matched to GaSb using both techniques. The sample grown by digital alloy technique showed stronger photoluminescence intensity, narrower peak linewidth, and larger carrier activation energy than the random alloy technique, indicating an improved optical quality with lower density of non-radiative recombination centers. In addition, a relatively long carrier lifetime was observed from the digital alloy sample, consistent with the results obtained from the photoluminescence study.

Highlights

Sb-based compound semiconductors are attractive for advanced optoelectronic applications because of their capability to form ternary and quaternary alloys that allow flexible bandgap engineering, which can be grown lattice-matched to common substrates such as InAs, InP, and GaSb [1,2,3,4,5]
Mixed-anion alloys rely on random alloy (RA) growth in which direct deposition of atoms on the sample surface with carefully tuned growth parameters to achieve the targeted alloy composition
The digital alloy (DA) growth has been shown to offer a precise control over alloy composition and reproducibility against RA growth [14,15]

Summary

Introduction

Sb-based compound semiconductors are attractive for advanced optoelectronic applications because of their capability to form ternary and quaternary alloys that allow flexible bandgap engineering, which can be grown lattice-matched to common substrates such as InAs, InP, and GaSb [1,2,3,4,5]. Mixed-anion alloys rely on random alloy (RA) growth in which direct deposition of atoms on the sample surface with carefully tuned growth parameters to achieve the targeted alloy composition. The DA growth has been shown to offer a precise control over alloy composition and reproducibility against RA growth [14,15]. Such a technique has been widely implemented to facilitate growths of III-(As, Sb) alloys in device applications [10,16,17,18], a direct comparison of the material properties of those alloys grown by DA and RA has not been reported

Methods

Results

Conclusion