Size effect on parameters characteristic of polar GaP crystals

All the parameters characteristic of the GaP crystal doped with O_p and Zn_Ga are investigated and compared to those of the same crystal but doped with S_p and Zn_Ga, basing on a deformation potential model related to the size effect. It is shown that the dilatation resulting from this effect decreases not only the band gap but also the other values of the parameters characteristic of the pure crystal. The band gap of the GaP crystal doped with O and Zn is found to be 1.556eV and it is thus equal approximately to that of the pure CdTe crystal at low temperatures.