Reduction of defect density by rapid thermal annealing in GaAsBi studied by time-resolved photoluminescence

Abstract

Time-resolved photoluminescence was performed on as-grown and annealed bulk GaAsBi samples. Rapid thermal annealing was carried out at a temperature of 750 • C. With annealing, we observed a significant change in the photoluminescence decay time at low temperature and low excitation power, which is likely due to a reduction of localized states. Although the time-integrated photoluminescence intensity did not show a large variation, this enhancement was confirmed by the observed removal after annealing of the S-shape behaviour present in the as-grown sample.

Novel Dilute Bismide, Epitaxy, Physical Properties and Device Application

“…Both the x Bi = 4% and the x Bi = 4.8% samples show an S-shape trend of PL peak energy as a function of temperature and the RTA at 700 • C for 30 s has almost no effect on removal of the S-shape for the x Bi = 4% sample but slightly mitigates the localization for the x Bi = 4.8% sample. In another study by Mazzucato et al [146] with x Bi = 2.3% in a 200 nm thick GaAsBi, the S-shape behavior appears at a low excitation of 1 mW but disappears at an elevated excitation power of 10 mW, because a high excitation power can saturate the localized traps. After annealing at 750 • C, the S-shape disappears and the PL peak energy shows a blue-shift of 5 meV.…”

“…There are a number of annealing studies reported and they are summarized in Table 5 below. Most previous reports focus on RTA of GaAsBi grown by both MBE [141,[143][144][145][146][147] and MOCVD [148,149]. The growth temperature used is between 200 and 420 • C measured by a thermocouple.…”

“…Post-growth RTA is performed at 500-900 • C for a typical duration of 30-900 sec. The most common assessment methods are HRXRD and PL, while other methods like time-resolved PL [144,146] and PR [149] are sometime used.…”

Variation of lattice constant and cluster formation in GaAsBi

“…[1][2][3][4][5][6][7][8][9][10] Adding small amounts of Bi to the GaAs lattice leads to a large reduction of the band gap, enabling access to important wavelengths in the infrared region. However, the successful incorporation of Bi within the GaAs lattice requires the use of unconventional growth procedures, such as growth temperatures near or below 400 C and a strict control of the As flux.…”

“…Several works have been made concerning the effect of thermal annealing on GaAsBi, however, no clear conclusions can be made yet. The GaAsBi layers studied in those works were grown at relatively high temperatures between 345 C and 420 C. [4][5][6][7][8][9] Generally, X-ray diffraction (XRD) measurements of GaAsBi layers showed no significant structural deformations up to annealing temperatures of 700-800 C, suggesting good thermal stability. 5,6,8 Furthermore, while some studies reported improvements in the photoluminescence (PL) intensity, 6,8 other works reported little or no improvement.…”