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Morphologies and photoluminescence properties of gallium nitride‐based thin films grown on non‐single‐crystalline substrates were investigated. The films were directly grown on quartz glass and amorphous‐carbon‐coated graphite substrates by a molecular beam epitaxy apparatus which has dual nitrogen plasma cells. Co‐supplying of indium and gallium with simultaneous operation of the dual nitrogen plasma cells brought isolated and nano‐pillar‐shaped structures to the films. On the other hand, such structures were not obtained when the films were grown by the single plasma cell operation. Photoluminescence (PL) properties of the films greatly depended upon the morphologies. The intensities of the PL peaks emitted from the films which have such nano‐pillar shaped structures were quite intense although the peak energies shifted to lower energy sides compared with those of the films grown by the single plasma cell operation.

The growth of gallium nitride-based nanopillar-shaped crystals on the multicrystalline silicon substrate that is widely employed in solar cells is presented here for the first time. The nanopillar-shaped crystals are successfully grown on the multicrystalline substrate in a manner similar to the structures grown on other substrates. Structural variations and a highly enhanced band edge emission in the photoluminescence spectrum have been observed using germanium doping.

A gallium nitride-based thin film is grown on a multicrystalline Si substrate by a molecular beam epitaxy apparatus. The microstructure of the crystalline film is closely examined by transmission electron microscopy (TEM). It is revealed that the film is composed of nanopillar-shaped-crystal grains with their diameters of 100 nm and heights of 400 nm approximately. Each nanopillar-crystal grain is based on highly-ordered wurtzite crystal structure and strongly textured with its c-axis oriented perpendicular to the substrate surface. The TEM observations also evidence that there are two kinds of basal stacking faults widely distributed in the nanopillar-crystal.

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