EPR and electrical studies of native point defects in ZnSiP2 semiconductors

We present the first detection of native defects in ZnSiP2. Similar to p-type ZnGeP2, the EPR spectra of the zinc vacancy VZn-, the phosphorus vacancy VP0, as well as of group IV anti-site SiZn+(GeZn+) could be proved. The influence of the group IV-ions on the bonding behavior for the different lattice sites is reflected in the differences of the EPR parameters in both lattices. In both materials, VP0 could be observed only by photo-excitation, whereas the silicon anti-site SiZn+ was detectable also in the dark contrary to GeZn+. This is connected with the shift of the Fermi level in the n-type ZnSiP2 samples. In disagreement with the recharching model developed for the dominant native defects in ZnGeP2 we could detect both SiZn+ and VZn- in the dark. This contradiction could be resolved by scanning surface potential microscopy measurements, which have shown that the Fermi level position laterally varies in these samples, realizing the paramagnetic states of both defects in different regions of the sample