Photoluminescence study of hydrogen passivation of ZnTe

Hydrogen passivation of single crystal ZnTe is being reported for the first time. ZnTe was synthesized from ultra-high purity elements in our laboratory by microwave heating and crystals grown by very slow Bridgman technique in sealed ampoules. Bandgap of the crystals was found to be 2.26 eV at 300 K. H passivation was carried out in a plasma chamber with 100 W r.f. power at 13.56 MHz. Duration of the plasma treatment was varied from 30 to 90 min., the sample temperature being kept at 250 degrees C. Before hydrogen treatment PL peaks were observed at 2.06, 1.47, 1.33 and 1.05 eV. After 30 min. of passivation, the peak at 2.06 eV disappeared while new peaks were observed at 2.34 and 2.19 eV. After 60 min. of hydrogenation, near band-edge green luminescence was observed at 2.37 eV. 90 min. of exposure to the plasma caused severe damage to the sample surface showing only 2.19 eV peak in addition to those at 1.47, 1.33 and 1.05 eV. These three bands were not effected by hydrogenation.