New process for formation of gallium nitride thin films locally on selected areas

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As a new method to form hydrogen-free gallium nitride (GaN) thin layers, ion beam direct deposition method under nitrogen ambient was investigated. After 100 eV Ga ion beam was irradiated on a chip of a Si(111) wafer under a nitrogen-radical atmosphere, the composition and the chemical bonding nature of the deposited materials were investigated by X-ray photoelectron spectroscopy (XPS). The XPS spectra of the deposited Ga under nitrogen-radical were very similar to that of an epitaxially grown GaN reference, indicating the possibility of the formation of GaN thin layer using the present method. Because the pure N_2 gas was used as the nitrogen-radical source, no impurity fragments should be incorporated in the deposited materials. As a result, it is shown that the formation of hydrogen-free GaN layers is possible by the present method.In addition, we report the formation of GaN layer at outermost surface of SiN films by using low-energy (60-200 eV) Ga ion irradiation. It is found that the Ga ions were surely implanted in the insulative SiN surface, and the position of the XPS signal of Ga was shifted to 20.2 eV, showing the existence of Ga-N bonds. Because the ion energy used was large enough to break the Si-N bonds, this result shows that the N atoms can be bonded easily with implanted Ga atoms than Si atoms. These low-energy Ga-implanted SiN regions might be used as nucleation sites in the growth of GaN layers. The present result indicates that this method has a potential to fabricate GaN films on any kinds of materials, only if the SiN layer was able to be formed on them, resulting the formation of multifunctional Si devices and the possible substitution of sapphire and SiC substrates to another low-priced materials such as Si and glass.