DEEP-LEVEL CHARACTERIZATION OF N-TYPE GAAS BY PHOTOREFLECTANCE SPECTROSCOPY

Photoreflectance (PR) signal of n-type GaAs grown by molecular-beam epitaxy has been systematically studied as a function of modulation frequency in the PR measurements. The trap activation energy obtained from analysis of the frequency response of PR signal with its temperature dependence is 0.34 eV. The dramatic change in the frequency response has been observed as a function of the modulation (ac) and bias (dc) light intensities. The theoretical analysis has been made by assuming a single level electron trapping model. The calculated result shows a good agreement with the experimental data. Furthermore, photoluminescence spectrum associated with the deep level of the molecular-beam-epitaxy-grown GaAs was measured and compared with the PR data.