Optical and defect properties of S-doped and Al-doped GaSe crystals

S-doped and Al-doped GaSe crystals are promising materials for their applications in nonlinear frequency conversion devices. The optical and defect properties of pure, S-doped, and Al-doped GaSe crystals were studied by using photoluminescence (PL) and Fourier transform infrared spectroscopy (FT-IR). The micro-topography of (0001) face of these samples was observed by using scanning electron microscope (SEM) to investigate the influence of the doped defects on the intralayer and interlayer chemical bondings. The doped S or Al atoms form the S-Se(0) or Al-Ga(+1) substitutional defects in thelayer GaSe structure, and the positive center of Al-Ga(+1) could induce defect complexes. The incorporations of S and Al atoms can change the optical and mechanical properties of the GaSe crystal by influencing the chemical bonding of the layer structure. The study results may provide guidance for the crystal growth and further applications of S-doped and Al-doped GaSe crystals.