The photoluminescence (PL) spectra of Sample A under resonant excitation at the wavelength of 915 nm, at 150 K, and under an incident light with a power of 65 mW. (a) The PL spectra of Sample A measured for the open-circuit condition with a 0.7-V bias using a laser power excitation of 65 mW. The PL intensity decreases by 7.3% when a 0.7-V bias is applied on Sample A. The PL peak position of Sample A for the open-circuit condition is 1123 nm and is red-shifted to 1125 nm when a 0.7-V bias is applied. This red shift arises from the energy band slant under the applied electric field. (b) Excitation-power-dependent PL integrated intensity and peak wavelength of the PL spectrum for the open-circuit and 0.7-V bias conditions. The percentage of the PL intensity decreases from 90% to 65% with the decrease of the light power. The PL peak position is blue-shifted from 1126 nm to 1123.2 nm and from 1128 nm to 1125.1 nm for the open-circuit and 0.7-V bias conditions, respectively. The PL peak positions are blue-shifted when the laser power is increased because of the band-filling effect.