Exciton Absorption in GaSe under Intense Excitation

抄録

High excitation absorption was investigated in GaSe at 2 K and 77 K, using a N₂ laser. Change in absorption coefficient was measured directly by a pulse-modulation technique. A structure was found at an excitonic transition around 2.1 eV. The structure shows peak shift and broadening of an exciton absorption line. Shift and broadening are due to an elastic collision between two excitons. Two kinds of induced absorption were also observed. One is possibly ascribed to exciton excitation associated with collision with the second exciton and the other to excitation of a trapped electron to a conduction band.