SIMS analysis of ZnO films co-doped with N and Ga by temperature gradient pulsed laser deposition

Composition spread ZnO:(Ga,N) films were deposited on ScAlMgO4 substrates using both temperature gradient method and alternating pulsed laser deposition (PLD) onto two targets of highly-pure and Ga-doped ZnO. The intensity ratios of 14N16O and 71Ga16O to that of 70Zn16O detected by secondary ion mass spectroscopy (SIMS) analysis were found to correspond to N and Ga concentrations (CN and CGa), respectively. Incorporation of nitrogen into ZnO film with O-face ( c) polarity deposited by PLD depended strongly on substrate temperature due to thermal-activated desorption of N, while CN into Zn-face (þc) ZnO film was independent of the temperature. The ratio of CN/CGa in the ZnO:(Ga,N) film covered a wide range including the value of 2, satisfying the theoretical prediction to produce p-type carrier in ZnO, at various CGa levels (1018–1020 cm 3). However, p-type conduction was not observed in Hall bars array patterned on the composition spread films. The temperature gradient method and the quantitative SIMS analysis revealed that simple adjustment of CN/CGa ratio was not able to lead to production of p-type ZnO film. # 2003 Elsevier B.V. All rights reserved