AVS 53rd International Symposium
    Electronic Materials and Processing Tuesday Sessions
       Session EM-TuM

Paper EM-TuM9
Study of Impurities and Dopants in CVD Grown ZnO:N

Tuesday, November 14, 2006, 10:40 am, Room 2003

Session: Zinc Oxide
Presenter: S.E. Asher, NREL
Authors: S.E. Asher, NREL
T.M. Barnes, NREL
X. Li, NREL
C.L. Perkins, NREL
M.R. Young, NREL
T.J. Coutts, NREL
Correspondent: Click to Email
ZnO is an attractive material for optoelectronics due to its wide bandgap and use as a transparent conductor in photovoltaic devices. Reported work shows the ability to dope this material both n- and p-type.@footnote 1@ Films grown by metalorganic chemical vapor deposition (MOCVD) and plasma enhanced chemical vapor deposition (PECVD) have demonstrated p-type conductivity when doped with nitrogen, however, hole concentrations and mobilities are low, and films spontaneously type-convert over time.@footnote 2,3@ Compensation and/or passivation of the nitrogen acceptors by impurities such as carbon and hydrogen are thought to contribute to the poor electrical properties. In this work we have used SIMS and XPS to study contaminant and nitrogen doping levels in ZnO and ZnO:N films grown by MOCVD, PECVD and reactive sputtering. The CVD material is found to contain high levels of carbon and hydrogen, while sputter deposited material is considerably cleaner. We find decreasing carbon and hydrogen as a function of growth temperature for undoped MOCVD grown material. However, we find significant differences in the carbon and hydrogen in both CVD processes when nitrogen is present. For N-doped MOCVD films we also find carbon content appears to be linked to the proportion of oxygen in the deposition ambient. A similar relationship is not observed for N-doped PECVD or sputter deposited material. XPS indicates the presence of carbon bound to nitrogen in the MOCVD material. The relationship between carbon and hydrogen impurities, and nitrogen doping will be discussed.@footnote 4@ @FootnoteText@ @footnote 1@S.J. Pearton, et.al., Prog. Mater. Sci., 50, 293 (2005). @footnote 2@X. Li, et.al., J. Vac. Sci. Tech., A.21, 1342 (2003). @footnote 3@T.M. Barnes, et.al., Appl. Phys. Lett., 86, 112112 (2005). @footnote 4@This work was performed with the support of US Department of Energy Contract No. DE-AC36-99GO10337. This abstract is subject to government rights.