HYDROGENATION EFFECT ON OPTICAL AND ELECTRICAL-PROPERTIES OF UNDOPED P-CDTE

Photoluminescence, capacitance-voltage and Hall measurements were carr ied out in order to investigate the hydrogenation effect on the behavi or of defects, bound excitons, and accepters for undoped p-CdTe. After the CdTe was treated at 80 degrees C for 30 min using a plasma-enhanc ed chemical vapor deposition system, a broad exciton bound peak at 1.5 90 eV (A degrees X) was resolved into three peaks: an A degrees X (1.5 85, 1.588 eV), a neutral donor-bound exciton (D degrees h) at at 1.591 eV, and an exciton bound to a ionized darter (D+ X) at 1.592 eV. The luminescence due to recombination of the electrons in the conduction b and with the accepters (e, A degrees) and due to the donor-acceptor pa ir (DAP) transition remarkly decreased after hydrogenation. Also, the defect band in the few-energy range (1.4-1.53 eV) vanished. Electrical measurements showed that the acceptor concentration was lowered by an order of magnitude from the surface to 2 mu m in comparison to the as -grown CdTe. p-type CdTe was converted to ra-type CdTe, and the resist ivity and mobility after hydrogenation was raised by as much as about 10(3) and 12 times, respectively, in comparison to the as-grown CdTe. From the above results, it is suggested that hydrogen atoms effectivel y passivate not only accepters related to the Cd vacancies but also do nors and that the type of the CdTe can be changed by hydrogenation.