Single crystal growth of GaSe via bismuth flux method and its air-stability

Gallium selenide (GaSe) shows potential applications in photoelectric fields. Herein, we successfully synthesized GaSe single crystal with large size via improved Bi-flux method. X-ray diffraction pattern and energy dispersive spectrum show the high crystallinity and high homogeneity of GaSe crystal. Optical absorption and photoluminescence measurements illustrate the band gap of the crystal is ~ 2 eV. Photocurrent behavior demonstrates the photoelectric response time is determined to be 2.08 s. The time dependent Raman spectrum shows that GaSe grown by Bi-flux method degenerates slowly under continuous air-exposure. This effective new growth method would be helpful for photoelectric device and two-dimensional materials study based on GaSe.