Semi-insulating ZnSip2

Results of Hall effect and conductivity measurements on semi-insulating undoped p-type ZnSiP2 (prepared as well from a Zn melt as by vapour phase transport growth) are reported. Te reason of the semi-insulating behaviour is a deep acceptor level located at (0.70 ± 0.07) eV above the valence band. The ZnSiP2 crystals have an electrical conductivity of about 10−9 Ω−1 cm−1 at room temperature and a hole concentration < 1014 cm−3 at 500 K. The mobilities lie between 1 and 6 cm2/Vs and obey the T−3/2 law for acoustical mode scattering above 500 K. By Cu diffusion into low-resistivity n-type ZnSiP2 semi-insulating p-type ZnSiP2 has been produced. The results seem to prove that the deep level in the undoped material is due to a copper but not to a simple copper impurity.