Impurity levels in layered semiconductor n-InSe doped with Ge

The impurity levels in Ge‐doped n‐InSe have been investigated by using photoluminescence (PL), photocurrent (PC), and Hall effect measurements. Two emission bands related with impurity level are observed at about 1.28 and 1.25 eV in PL spectra at 77 K. In addition to the results of temperature dependence of PC spectra and electron concentration, it is found that the 1.28 and 1.25 eV emission bands are associated with the donor levels at about 0.09 and 0.06 eV below the conduction band, respectively. The effect of excitation intensity of peak energy for the 1.25 eV emission band is characterized by the donor–acceptor recombination. The temperature dependence of mobility is influenced by adding an amount of Ge atom. The scattering mechanism of the 0.05 at.% Ge‐doped sample can be well explained by the combined mechanism of the optical phonon, ionized impurity and neutral impurity scatterings.