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利用金属有机气相外延方法研究了非故意掺杂GaN薄膜的方块电阻与高温GaN体材料生长时载气中N2比例的关系.研究发现,随着载气中N2比例的增加,GaN薄膜方块电阻急剧增加.当载气中N2比例为50%时,GaN薄膜方块电阻达1.1×108Ω/□,且GaN表面平整,均方根粗糙度为0.233 nm.二次离子质谱分析发现,载气中N2比例不同的样品中碳、氧杂质含量无明显差别.随着载气中N2比例的增加,GaN材料中螺型位错相关缺陷密度无明显变化,而刃型位错相关缺陷密度明显增加.结果表明,刃型位错的受主补偿作用是导致GaN薄膜方块电阻变化的主要原因.
The relationship between the sheet resistance of unintentionally doped GaN thin films and the N2 content of carrier gas during the growth of high-temperature GaN bulk material was investigated by metal-organic vapor phase epitaxy method. It was found that the sheet resistance of GaN thin films rapidly with the increase of N2 in carrier gas When the proportion of N2 in the carrier gas is 50%, the sheet resistance of the GaN thin film reaches 1.1 × 108Ω / □, and the GaN surface is flat with a root mean square roughness of 0.233 nm.Secondary ion mass spectrometry analysis shows that the N2 ratio The contents of carbon and oxygen in different samples show no significant difference.With the increase of N2 in the carrier gas, there is no obvious change in the density of defects related to screw dislocation in GaN, but the density of defects associated with edge dislocation increases obviously. The main reason for the change of resistance of GaN thin film is the acceptor compensation effect of edge dislocation.