Characterization of low-temperature molecular-beam-epitaxy grown GaBiAs layers

Abstract

GaBiAs layers with Bi content reaching 8.4% are grown by MBE technique at low temperatures. All layers were of p-type with carrier densities ranging from 3 × 10 14 to 2 × 10 15 cm −3 and resistivities exceeding 60 cm. Energy bandgap of the gallium bismide alloys as determined from spectral measurements of the optical absorption, photoconductivity and photoluminescence decreases linearly with increasing Bi content. Optical pump-terahertz probe measurements made on these layers show that the carrier density dynamics is best described by a double-exponential decay. The shorter of the time constants corresponds to the electron trapping and the longer time constant corresponds to the trap emptying times. It has been found that the electron trapping cross-section is of the same order of magnitude as the corresponding parameter for As-antisite traps in LTG GaAs; therefore, it is reasonable to assume that As antisites play a significant role in carrier recombination processes in GaBiAs, too.

Novel Dilute Bismide, Epitaxy, Physical Properties and Device Application

“…By comparing the reduced effective mass and exciton radius of each PL process, they clarified that the interface of GaSbBi/AlGaSb QW is a terrace-like structure, due to the Bi-induced interfacial Al/Ga inter-diffusion. [20,21,25,29,44,74,149,161,165,168,185,188,190,205,212,[235][236][237].…”

Investigations of various cw terahertz photomixers

“…THz signal generated by the same spiral-type emitter using detector devices made from LTG GaAs (dotted line) and GaBiAs (full line). GaAs is typically lower than 1000 cm 2 /(V s), whereas LTG GaBiAs, although characterized by subpicosecond electron lifetimes [8] as short as in LTG GaAs, has electron mobilities exceeding 2000 cm 2 /(V s) [9,10]. As seen from Fig.…”

“…In this work we have additionally investigated a THz detector manufactured from GaBi 0.04 As 0.96 epitaxial layer grown by MBE on a semi-insulating GaAs substrate at the temperature of 320 • C [9]. Results of coherent detection of the signal, emitted by the same spiral-type emitter using devices made from LTG GaAs and GaBiAs, are compared in Fig.…”

Semiconductor materials for ultrafast optoelectronic applications

“…Bismuth content in epitaxial layers was measured by two techniques: XRD using a Cu Kα 1 line and Rutherford backscattering spectroscopy [35]; both techniques have led to very close results for all GaBiAs layers investigated. Energy bandgap of the GaBi x As 1−x alloys was also investigated by several independent experiments: spectral measurements of optical absorption, photoconductivity, and photoluminescence.…”