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Attempts to prepare single crystal gallium nitride in thin films and bulk form are reported. The thin films were prepared by reacting GaCI, and NH, and depositing on to single crystal silicon carbide substrates. The bulk gallium nitride was prepared by the conversion of single crystals of gallium arsenide using an intermediate oxide phase.The structural perfection of the gallium nitride material thus formed has been assessed using X-ray diffraction and electron diffraction techniques. Both methods of preparation produced single phase gallium nitride exhibiting a high degree of structural disorder.

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The preparation of d.c. electroluminescent thin films of copper- and manganese-activated ZnS is described together with their electrical and luminescent characteristics. Films have been prepared from activated powders by sublimation in a horizontal two-zone vacuum furnace. Reproducible luminescent emission was obtained in the low-voltage operation range 10-20 V, and in a number of cases emission was observed at voltages as low as 7-8 V. Their electrical characteristics are governed by bulk conduction processes and show a strong dependence on deposition temperature. A theoretical model is proposed to explain the conduction mechanism in terms of bulk properties only. A relationship of the form V=A0+A1 ln I+A2I½ was found to give good agreement with the experimental results.