Investigation of deep level defects in n-type GaAsBi

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Dilute bismides are a promising class of semiconductors that find applications in mid-infrared optoelectronic devices, especially lasers, photodetectors, and heterojunction solar cells owing to the tenability of the bandgap, the low temperature dependence of their physical properties, and the low Auger recombination coefficient. In this paper we investigate on the defects and deep levels in n-type GaAs1-xBix (x = 1.2 %) Schottky barrier diodes grown by low-temperature molecular beam epitaxy (MBE). Original results obtained by means of capacitance deep level transient spectroscopy (C-DLTS) indicate that: (a) only four majority and two minority carrier traps with concentration below 10¹⁴ cm^-3can be detected in the probed regions and (b) the concentration of the defects is weakly position-dependent, thus indicating that MBE is an effective growth technique to control defect formation. The analysis of the carrier capture kinetics of the dominant electron and hole traps show that (c) they are associated to a dislocation and a point defect with capture barrier of 0.48 eV, respectively. Finally, by comparing the DLTS signatures of the detected defects, we proved (d) that only a deep level is possibly associated to the presence of the bismuth, while the others were already found in pure GaAs.