Low-temperature photoacoustic spectra of n-InSe

Using a ZnO transducer, two peaks at 1.250 and 1.212 eV in the photoacoustic spectra of n-InSe were obtained at 300K. The energy and its temperature variation of the 1.250 eV peak are well explained in terms of a free exciton annihilation. Another peak at 1.212 eV is interpreted by a surface related transition. The results suggest the usefulness of the low-temperature photoacoustic studies on the recombination processes in semiconductors.