The GaN substrate with a low in-plane dislocation density showed a small radius of curvature. There was a strong relationship between the in-plane dislocation density and lattice bowing. It was revealed that dislocations are present in a plane normal to the growth direction in addition to conventionally-known threading dislocations these are referred to as the in-plane dislocations. To further reduce dislocation density, we demonstrated a multiple-step growth technique based on the above two-step growth and succeeded in the GaN substrate with the overall dislocation density on the order of 10^4?10^5 /cm^2.Ī mechanism of the lattice bowing of freestanding GaN substrates grown on sapphire substrate was also investigated. The dislocation density of the GaN substrate using two-step growth technique was on the order of 10^5?10^6 /cm^2. We introduced a two-step growth technique involving a reduction of the dislocation density using facet growth as the first step and flattening growth of the GaN layer as the second step. Resume : In this paper, we report fabrication of the GaN substrates with overall low dislocation density and mechanism of lattice bowing of freestanding GaN substrates grown by hydride vapor phase epitaxy (HVPE). Authors : Narihito Okada1, Keisuke Yamane2, Tohoru Matsubara1,3, Shin Goubara1, Hiroshi Ihara1, Kota Yukizane1, Tatsuya Ezak1i1, Satoru Fujimoto1, Ryo Inomoto1, Kazuyuki Tadatomo1Īffiliations : 1 Yamaguchi University, 2 Toyohashi University of Technologyģ UBE Scientific Analysis Laboratory, Inc.
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