GaAsBi/GaAs multi-quantum well LED grown by molecular beam epitaxy using a two-substrate-temperature technique

Abstract

We report a GaAsBi/GaAs multiple quantum well (MQW) light emitting diode (LED) grown by molecular beam epitaxy using a two-substrate-temperature (TST) technique. In particular, the QWs and the barriers in the intrinsic region were grown at the different temperatures of [Formula: see text] = 350 °C and [Formula: see text] respectively. Investigations of the microstructure using transmission electron microscopy (TEM) reveal homogeneous MQWs free of extended defects. Furthermore, the local determination of the Bi distribution profile across the MQWs region using TEM techniques confirm the uniform Bi distribution, while revealing a slightly chemically graded GaAs-on-GaAsBi interface due to Bi surface segregation. Despite this small broadening, we found that Bi segregation is significantly reduced (up to 18% reduction) compared to previous reports on Bi segregation in GaAsBi/GaAs MQWs. Hence, the TST procedure proves as a very efficient method to reduce Bi segregation and thus increase the quality of the layers and interfaces. These improvements positively reflect in the optical properties. Room temperature photoluminescence and electroluminescence (EL) at 1.23 μm emission wavelength are successfully demonstrated using TST MQWs containing less Bi content than in previous reports. Finally, LED fabricated using the present TST technique show current-voltage (I-V) curves with a forward voltage of 3.3 V at an injection current of 130 mA under 1.0 kA cm current excitation. These results not only demonstrate that TST technique provides optical device quality GaAsBi/GaAs MQWs but highlight the relevance of TST-based growth techniques on the fabrication of future heterostructure devices based on dilute bismides.

HRTEM Study of Size‐Controlled Bi Quantum Dots in Annealed GaAsBi/AlAs Multiple Quantum Well Structure

“…Substitution of As by Bi in GaAs lattice produces a much larger reduction in the band gap (60–80 meV/%Bi) than alloying by In or Sn, thus making this material attractive for infrared radiation emitters and detectors . Devices with GaAsBi active layers are already reported, including 1.23 μm wavelength GaAsBi/GaAs MQW light emitting diodes, as well as 1.142 μm wavelength GaAsBi/GaAs single quantum well lasers …”

Microstructure and interface analysis of emerging Ga(Sb,Bi) epilayers and Ga(Sb,Bi)/GaSb quantum wells for optoelectronic applications

“…Unfortunately, in the present situation, there is a lack of suitable references (e.g., the not-yet synthesized endpoint GaBi compound 1 ), thus limiting EDS quantitative capabilities and awarding g 002 DFTEM a potential suitability for chemical quantification in this material system. Furthermore, g 002 DFTEM imaging is a very valuable technique for the investigation of compositional inhomogeneities in Ga(As,Bi) 7,8,22 since it allows the detection of small variations (around 0.5%) in the Bi content and, in particular, of composition fluctuations which cannot be detected using conventional XRD techniques. 23 Theoretical estimations of the g 002 diffracted intensity in Ga(Sb,Bi) predict, however, that the intensity contrast to GaSb is extremely low, with I 002-GaSbBi /I 002-GaSb 1.19 for Ga(Sb,Bi) with 14% Bi, which is in marked difference to Ga(As,Bi) where I 002-GaAsBi /I 002-GaAs 4.7 for Ga(As,Bi) with 14% Bi, as observed in Fig.…”

“…Both Ga(Sb,Bi)-on-GaSb and GaSb-on-Ga(Sb,Bi) interfaces are rather symmetric and exhibit a similar interface width, which also rules out the presence of strong Bi segregation. 8,22 In general, there are no visible differences in the morphology of the QWs in the reference sample and in the laser structure (cf. Figs.…”

Low-Frequency Noise Investigation of 1.09 μm GaAsBi Laser Diodes

“…Bismuth containing GaAs (GaAs 1- x Bi x ) is a novel and very promising material system for optoelectronic devices, especially in fiber optic communication laser diodes (LDs) operating in the (1.3–1.5) μm wavelength region due to numerous advantages [1,2]. Firstly, the incorporation of a small amount of Bi atoms into GaAs leads to a strong band gap energy reduction by (84–91) meV/%Bi [3], as well as temperature coefficient of the band gap being less sensitive to temperature [3,4].…”