Electrical and optical studies of metal organic chemical vapor deposition grown N-doped ZnO films ZnO synthesis by high vacuum plasma-assisted chemical vapor deposition using dimethylzinc and atomic oxygen J.A high-vacuum plasma-assisted chemical-vapor deposition system was used to systematically study ZnO:N thin film synthesis. Nitrogen doping was achieved by mixing either N 2 O or N 2 with O 2 in a high-density inductively coupled plasma (ICP) source. In situ diagnostics showed that the ICP composition was predominantly a function of the elemental oxygen to nitrogen ratio, and relatively insensitive to the choice of N 2 or N 2 O as the molecular precursor. Nitrogen incorporation was measured by both x-ray photoelectron spectroscopy and secondary ion mass spectrometry and was found to increase monotonically with both N 2 O and N 2 addition. Nitrogen doping was correlated with systematic shifts in the lattice spacing, electrical conductivity, and optical absorption. Quantitative comparisons between film properties and gas composition suggest that atomic nitrogen is the primary precursor for doping in this system.

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Plasma-enhanced chemical vapor deposition ͑PECVD͒ of zinc oxide was accomplished using diethyl zinc, oxygen, and argon in a capacitively coupled reactor. The plasma chemistry was studied by optical emission spectroscopy ͑OES͒ with particular focus on the effects of reactant composition and rf power. Process-property relationships were established by comparing plasma behavior with resulting film properties as characterized by the Hall effect, spectroscopic ellipsometry, and X-ray diffraction. In our studies of stoichiometry it was observed that the plasma chemistry was very similar to hydrocarbon combustion, so much so that the results were interpreted by borrowing the concept of the equivalence ratio, . For fuel-rich conditions ( Ͼ 1) deposition was dominated by incorporation of atomic Zn, the films were randomly oriented, and electrically insulating. In contrast fuel-lean conditions produced conducting films with a preferred ͑0 0 2͒ orientation. The results indicate that OES may be useful for calibrating oxide PECVD systems that employ bubblers to deliver organometallic precursors. It was also shown that increasing the plasma power had the same effect of decreasing , which was to drive the chemistry toward complete combustion. Electrical properties improved exponentially with both increased substrate temperature and decreased growth rate, highlighting the importance of surface migration in establishing carriers and controlling mobility.

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