Development of a 2-inch GaN wafer by using the oxide vapor phase epitaxy method

Abstract

From the previous studies, one of the challenges in the oxide vapor phase epitaxy (OVPE) method was suppressing poly-crystal generation for thick GaN growth. In this study, thick GaN growth was realized by controlling the supersaturation ratio using thermodynamic analysis, and an OVPE-GaN wafer of 300 μm-thick was obtained. As a result of evaluating the quality of the OVPE-GaN wafer, it was confirmed that both the high oxygen concentration and the high crystallinity were achieved. The resistivity was 7.75 × 10 −4 Ω cm and the threading dislocation density (TDD) was 8.8 × 10 4 cm −2 . It was newly found that the OVPE method can reduce TDD from the order of 10 6 cm −2 to the order of 10 4 cm −2 with a grown thickness of less than 500 μm. From these results, it was proved that the OVPE method has a great potential of manufacturing low resistivity and low TDD GaN wafers.

Structural Analysis of Low Defect Ammonothermally Grown GaN Wafers by Borrmann Effect X-ray Topography

“…Then, as a result of processing (wafering) procedures such as slicing, misorientation, drilling, grinding, lapping and mechanical polishing as well as chemo-mechanical polishing (CMP) one can obtain substrates from crystals. Today, three methods are applied for growing large in diameter GaN crystals: i. halide vapor phase epitaxy (HVPE) and its derivatives as oxide VPE (OVPE) or halide free VPE (HFVPE) [ 4 , 5 , 6 ]; ii. basic and acidic ammonothermal [ 7 , 8 ]; and iii.…”

Estimation of Shockley–Read–Hall Lifetime in Homoepitaxial n‐GaN on Low‐Dislocation‐Density GaN Substrates Prepared by Hydride Vapor Phase Epitaxy and Maskless 3D

“…We found a positive correlation between N dis and R on (symbols in Figure 5) [33] and discussed how such correlation under high-level injection conditions arise in relation to photon recycling. [30,31,55,[58][59][60][61][62] Namely, photon emission occurs in direct transition-type GaN by the recombination of electron-hole pairs at forward-biased conditions. The valence electrons are excited to the neutral Mg acceptors by the absorption of photons.…”

“…A record high breakdown voltage of 5 kV has been achieved in combination with a low on-resistance R on of 1.25 mΩ cm 2 at a forward voltage V F of 5 V. [14] The quality of substrates has also been improved. [22][23][24][25][26][27][28][29][30][31][32] For example, low-dislocation-density (N dis ≤ 4 Â 10 5 cm À2 ) GaN substrates became available via hydride vapor phase epitaxy (HVPE) and a maskless 3D (M-3D) method. [32] To suppress propagation of dislocations from the seed crystal, the M-3D method avoids c-plane growth; namely, the initial 3D growth is followed by 2D growth in which growth temperature and partial pressures of gallium chloride and ammonia are changed.…”

Extreme reduction of on-resistance in vertical GaN p–n diodes by low dislocation density and high carrier concentration GaN wafers fabricated using oxide vapor phase epitaxy method

“…In previous research, we reported the fabrication of a 2 inch GaN wafer via OVPE with low dislocation density, low-resistance, and high carrier concentration. 21) The dislocation density and resistivity were on the order of 10 4 cm −2 and 10 −4 Ω cm, respectively, which are both extremely low compared to those of typical GaN wafers. 22) The carrier concentration was in the upper half of the 10 19 cm −3 order, which is very high compared to that of typical GaN wafers.…”