Growth and characteristics of the CdTe (111)A face

The structural and the electro-optical properties of the CdTe (111)A face have been investigated by means of electro-optical methods. The CdTe crystal was grown by using the vertical Bridgman method. The minimum value of the full width at half maximum of the double crystal X-ray diffraction pattern and the pit density of the etched CdTe (111) A face were 38 arcsec and similar to10(4) cm(-2), respectively. These results suggest that the grown CdTe crystal was high quality. The energy band gap of the CdTe (111)A face obtained from the transmission measurement was 1.4702 eV at 300 K. The E-x and E-x-LO replicas were observed in the photoluminescence spectrum at 776.4 and 786.5 nm, respectively. The strong intensity peak of (Adegrees, X) at 779.8 nm was associated with the recombination emission of the excitons bound to shallow neutral acceptors. Thereby, the activation energy of acceptor level was estimated to be 69 meV, which was close to the ionization energy of acceptors due. to Li or Na impurities. The obtained results indicate that the grown CdTe (11 1)A face is sufficient for use as a substrate for CdS/CdTe solar cells.