Thin films of ZnO have been grown by low-pressure MOCVD using methylzinc isopropoxide, MeZn(OPi), and methylzinc tert-butoxide, MeZn(OBu*), in the absence of an added oxygen source. The films were grown on to glass substrates in the temperature range 250-400 "C with growth rates of between 0.2 and 4.4 pm h-'.

A series of undoped Sn02 films was grown by metallorganic chemical vapor deposition (MOCVD) from an Sn(OtBu)4 precursor. The characterization of their CO-and H20-gas sensing properties is reported. The films were very sensitive to low levels of CO at elevated temperatures (200 to 400°C), although a significant cross-sensitivity to relative humidity was found. Response and recovery times were very short in comparison with a Pt-doped thick film Sn02 pellet. The optimum working temperature was found to be 300 to 350°C, where linear responses to CO concentration and to relative humidity were seen once drift had been taken into account. All MOCVD films tested showed superior responses to a sputtered film. InfroductionThe metal oxide semiconductor tin oxide (Sn02) has a range of important applications, such as in transparent and conducting coatings on glass,1 and in gas-sensing devices used in a variety of applications.2 The require-

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Growth of epitaxial AIN from a directly bonded compound in the absence of any NH3, as described here, is an important technological advance. It is reported that the use of the adduct Me3AINH3 as a single‐source precursor has allowed the epitaxial growth on sapphire of AIN films of a quality suitable for buffer layers in the growth of device layers avoiding the disadvantages of traditional MOCVD of AIN. Details are given of deposition schemes, the carbon and oxygen contamination is discussed, and a probable deposition mechanism is proposed.

The metal oxide semiconductor SnO2 has a range of important applications, such as in transparent and conducting coatings on glass, and in gas‐sensing devices. CVD has a number of advantages as the technique of choice for the deposition of SnO2 thin films but development has in the past been hampered by the high toxicity of the available precursors and the necessity of adding an oxidant such as O2 or H2O. Here, SnO2 deposition from the relatively non‐toxic tetra‐t‐butoxide tin in the absence of added oxidant is reported. Platinum doping of the material is also discussed.