The authors report on the thermal activation of phosphorus doped p-type ZnO thin films grown by radio frequency magnetron sputtering. The p-type ZnO was produced by activating phosphorus doped ZnO thin films in N 2 , Ar, or O 2 ambients. The hole concentration of the p-type ZnO, prepared in an O 2 ambient, showed a lower hole concentration compared to samples annealed in N 2 and Ar ambients. The activation energies of the phosphorus dopant in the p-type ZnO under different ambient gases indicate that phosphorus atoms replace oxygen atoms in the ZnO to form P O which acts as an acceptor.

The effect of surface passivation of undoped p-CdTe(100) by (NH4)2Sx treatment was investigated by using photoluminescence (PL), photoconductivity (PC), and x-ray photoelectron spectroscopy (XPS). After sulfur treatment for 2 min, the acceptor bound exciton (A0, X) peak increases greatly in the PL spectrum, and the minority-carrier lifetime of CdTe becomes the longest value in the PC measurement. The XPS spectrum for untreated CdTe shows the additional peaks on the right side of two main Te peaks corresponding to the Te 3d core levels, and these additional peaks are related to TeO3 with binding energies of 576.2 and 586.5 eV. After sulfur treatment, while the intensities of the Te 3d core levels decreased gradually, those of the TeO3 peaks disappear. In addition, the S 2p core-level spectra for sulfur-treated CdTe show the peaks at the 161.7 and 162.8 eV, which are attributed to a CdS formation at the surface of CdTe. These results indicate the sulfur effectively dissociates the native oxides from and neutralizes the dangling bonds at the surface of CdTe.

A specific contact resistance of 8.9×10−5Ωcm2 was obtained for a Ni∕Au Ohmic layer on the KrF laser-irradiated p-GaN. It was found that laser irradiation increases the hole concentration from 4.1×1017to9.7×1017cm−3 by removing hydrogen atoms from p-GaN layer. The native oxide was also removed as evidenced by the Ga 2p peak shift and the decrease in the intensity of O 1s peak in the x-ray photoelectron spectra. The formation of a low resistance is attributed to the increase in the hole concentration and the removal of native oxide from p-GaN by laser irradiation.

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