Electron Irradiation Effects on GaSe 2D Material

Defects are crucial in tuning the electronic and optical properties of semiconductors. The development of advanced technologies in optoelectronics and other devices requires an understanding of the defects in semiconductor materials. This research is to study the effect of electron irradiation on GaSe multilayer 2D material, which is a semiconductor with an indirect bandgap of 2.0 eV and intrinsic p-type conductivity. The multilayer GaSe flakes were exfoliated mechanically from bulk material with taps and irradiated using high-energy electrons under ultra-high vacuum of ~ 6 x 10^-10 torr. The as prepared and irradiated samples are characterized by Raman and photoluminescence at variable temperatures. The typical Raman peaks of GaSe at ~133 cm^-1, ~211 cm^-1, and ~307 cm^-1 show no changes after electron irradiation. However, a new defect peak around ~250 cm^-1 is observed in the irradiated samples, and its intensity increases at higher electron dosages. The peak position of band-edge emission at 620 nm does not shift after electron irradiation, while a defect peak around 658 nm emerges with an increased intensity at higher dosages. The low-temperature Raman and PL are used to understand the underlying physics of the observed defect peak, which helps to have a better understanding of the irradiation effects on GaSe for defect control and applications.