Deep levels and carrier capture kinetics in n-GaAsBi alloys investigated by deep level transient spectroscopy

Abstract

Dilute bismides (%Bi ∼ 1%-3%) are excellent candidates for the fabrication of optoelectronic devices, thanks to the strong reduction in the bandgap with increasing bismuth content, the weak temperature dependence of the bandgap, and the small Auger recombination coefficient for high bismuth concentrations. Since Shockley-Read-Hall recombination may significant impact on the electrical and optical properties of the devices, describing the defects within the semiconductor material is of paramount importance for the optimization of device technology. To this aim, this paper investigates the deep levels within the bandgap in un-annealed n-type GaAsBi grown by molecular beam epitaxy at low temperature (390 • C) by means of deep level transient spectroscopy and filling time-dependent measurements. The original results described in the paper indicate (a) the presence of four majority and two minority carrier traps, and (b) that, from the analysis of the charge-capture kinetics, the dominant electron and hole traps originate, respectively, from a dislocation-related and a point defect with capture barrier of 0.48 eV. In addition, (c) we demonstrate that the incorporation of bismuth in GaAs generates only one additional electrically active defect with concentration higher than the sensitivity of the measurement setup, because most of the relevant traps found in GaAsBi layers have been identified in pure GaAs grown at low temperature. Finally, (d) the trap concentration is relatively constant along the growth direction, indicating a uniform defect density.

Raman scattering study on dilute nitride-bismide GaNAsBi alloys: behavior of photo-excited LO phonon-plasmon coupled mode

“…This is probably because the formation of deep-level traps was suppressed by Bi incorporation. 23) For the as-grown samples, the PL intensities of GaNAsBi and GaNAs were approximately three orders of magnitude smaller than those of GaAsBi. This indicates that N addition at the low growth temperature required for Bi incorporation introduces severe non-radiative recombination centers.…”

Improving the photovoltaic properties of GaAs/GaAsBi pin diodes by inserting a compositionally graded layer at the hetero-interface

“…Localized states both at shallow levels-i.e. tail states [11,[22][23][24]-and at deep levels [25] in GaAsBi have been studied previously. In particular, the generation of tail states-which are less likely to occur in other single-crystalline semiconductors such as Si, GaAs, and GaN-is a major issue.…”

High‐Field Electron‐Drift Velocity in n‐Type Modulation‐Doped GaAs0.96Bi0.04 Quantum Well Structure

“…Bismuth‐containing alloys have been studied widely due to their unusual properties, which enable the design of novel optoelectronic devices in NIR and MIR regions of the electromagnetic spectrum in place of conventional III–V‐based devices. [ 1–3 ]…”

“…Bismuth-containing alloys have been studied widely due to their unusual properties, which enable the design of novel optoelectronic devices in NIR and MIR regions of the electromagnetic spectrum in place of conventional III-V-based devices. [1][2][3] Even though the optical properties of GaAsBi have been intensively investigated, [4][5][6][7][8][9] there are limited studies on the electrical properties of both intentionally and unintentionally doped GaAsBi alloys. In these studies, the temperature dependence of carrier density and mobility and the effective mass for bulk GaAsBi have been determined.…”