Characterizations of arsenic-doped zinc oxide films produced by atmospheric metal-organic chemical vapor deposition

Abstract

p-type ZnO films were prepared by atmospheric metal-organic chemical vapor deposition technique using arsine (AsH3) as the doping source. The electrical and optical properties of arsenic-doped ZnO (ZnO:As) films fabricated at 450–600°C with various AsH3 flow rates ranging from 8 to 21.34μmol/min were analyzed and compared. Hall measurements indicate that stable p-type ZnO films with hole concentrations varying from 7.2×1015 to 5.8×1018cm−3 could be obtained. Besides, low temperature (17K) photoluminescence spectra of all ZnO:As films also demonstrate the dominance of the line related to the neutral acceptor-bound exciton. Moreover, the elemental identity and chemical bonding information for ZnO:As films were examined by X-ray photoelectron spectroscopy. Based on the results obtained, the effects of doping conditions on the mechanism responsible for the p-type conduction were studied. Conclusively, a simple technique to fabricate good-quality p-type ZnO films has been recognized in this work. Depositing the film at 550°C with an AsH3 flow rate of 13.72μmol/min is appropriate for producing hole concentrations on the order of 1017cm−3 for it. Ultimately, by increasing the AsH3 flow rate to 21.34μmol/min for doping and depositing the film at 600°C, ZnO:As films with a hole concentration over 5×1018cm−3 together with a mobility of 1.93cm2V−1s−1 and a resistivity of 0.494ohm-cm can be achieved.