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KMID : 0381920000300040337
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Korean Journal of Microscopy
2000 Volume.30 No. 4 p.337 ~ p.345
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Measurements of Lattice Strain in MOCVD-GaN Thin Film Grown on a Sapphire Substrate Treated by Reactive Ion Beam
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Kim Hyun-Jung
Kim Gyeung-Ho
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Abstract
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Introduction of the buffer layer and the nitridation of a sapphire substrate were one of the most general methods employed for the reduction of lattice defects in GaN thin films Brown on sapphire by MOCVD. In an effort to improve the initial nucleation and growth condition of the GaN, reactive ion beam (RIB) of nitrogen treatment of the sapphire surface has been attempted. The 10 nm thick, amorphous $AlO_xN_y$ layer was formed by RIB and was partially crystallized alter the main growth of GaN at high temperature, leaving isolated amorphous regions at the interface. The beneficial effect of amorphous layer at interface in relieving the thermal stress between substrate and GaN film was examined by measuring the lattice strain value of the GaN film grown with and without the RIB treatment. Higher order Laue zone pattern (HOLZ) of $[\bar{2}201]$ zone axis was compared with simulated patterns and lattice strain was estimated It was confirmed that the great reduction of thermal strain was achieved by RIB process and the amount of thermal stress was 6 times higher in the GaN film grown by conventional method without the RIB treatment.
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KEYWORD
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GaN, HOLZ, Reactive ion beam, Sapphire substrate, Lattice strain
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