Long wavelength stacking induced shift of the near-infrared photoluminescence from unintentional MOVPE grown InGaSb/GaSb quantum wells

Chinedu Christian Ahia,Beatriz Galiana Blanco,Amalia Navarro,Ngcali Tile,Johannes Reinhardt Botha

doi:10.1063/1.5037296

Abstract

The effect of stacking on the near-infrared photoluminescence (NIR-PL) of InGaSb/GaSb quantum wells (QWs) which were inadvertently formed during an attempt to fabricate stacked InSb/GaSb quantum dots (QDs) using atmospheric pressure Metalorganic Vapor Phase Epitaxy (MOVPE) are investigated in this work. The morphology of uncapped dots was studied by means of scanning probe microscopy (SPM) which shows a significant deviation in the shape and density of dots grown directly on the buffer compared to those that terminated an “embedded-dot” sample. Cross-sectional scanning transmission electron microscopy (STEM) and transmission electron microscopy (TEM) of the capped structures clearly revealed the formation of QWs in the capped structures. An increase in the number of InSb QD-layers, which metamorphosed into QWs, was observed to cause an increase in the luminescence spectral line width and a long-wavelength shift of the QW PL lines, together with an enhancement in the strength of PL emission. Variations in layer thicknesses and alloy composition introduced as a result of inter-diffusion of Ga and In which is enhanced by the prolonged annealing time of the QDs (during spacer/cap layer deposition) and In adatom migration is suggested to alter the morphology of the capped dots and induce a change in PL peak positions and the spectral linewidth of the NIR low energy lines.

Highlights

The fabrication of low dimensional semiconductor structures has attracted much attention because of their wide spread applications in opto-electronic devices
We extend our previous investigations[11,12] and report on the effect of stacking on the near-infrared photoluminescence (NIR-PL) properties of unintentional InGaSb/GaSb quantum wells (QWs), formed during an attempt to fabricate capped InSb/GaSb quantum dots (QDs)
The NIR-PL behaviour of stacked InGaSb QWs which were grown during an attempt to fabricate InSb QDs on a GaSb ((100) 2◦ off towards B ± 0.1◦) substrate was presented

Summary

INTRODUCTION

The fabrication of low dimensional semiconductor structures has attracted much attention because of their wide spread applications in opto-electronic devices. A reduction in the dimension of semiconducting materials from bulk three-dimensional (3D) semiconductors to zero-dimensional (0D) quantum dots (QDs) gives rise to striking changes in the behaviour of these materials, due to the confinement of electrons and/or holes. InSb/GaSb QDs are a promising alternative material system for mid-infrared (MIR) applications. Many studies[8,9,10] have reported PL emission of InSb/GaSb QDs within the near-IR (NIR) region; transmission electron microscopy (TEM) studies reported recently[11,12] have illustrated the inadvertent formation of an InGaSb quantum well (QW) after capping of InSb QDs, which gave rise to PL spectra similar to what has earlier been reported by some groups[8,9,10] to be emission from InSb QDs within the NIR region. We extend our previous investigations[11,12] and report on the effect of stacking on the NIR-PL properties of unintentional InGaSb/GaSb QWs, formed during an attempt to fabricate capped InSb/GaSb QDs

EXPERIMENTAL DETAILS

RESULTS AND DISCUSSION

CONCLUSION