Certain undesired phenomena are observed in n-GaN layers grown by metal–organic chemical vapor deposition (MOCVD) due to the unavoidable C-induced carrier compensation. They are a drastic reduction in carrier mobility, called mobility collapse, and significant non-uniformity in the carrier concentration due to the off-angle dependence of the C-incorporation efficiency of the process. These phenomena are particularly severe for low doping levels between 1015 and 1016/cm3, which are suitable for fabricating drift layers used in vertical-type GaN power devices that operate in the range of a few kilovolts to tens of kilovolts. However, the C-related undesired characteristics are absent in homo-epitaxial n-GaN layers grown by quartz-free hydride vapor phase epitaxy (QF-HVPE), recently developed by us. The utilization of C-free raw materials alongside quartz-free parts enables the growth of highly pure GaN crystals with negligible Si, C, and O incorporations. These crystals exhibited an electron concentration in the low-1015/cm3 range with the highest reported room temperature electron mobility, μ, of 1470 cm2/V s among GaN crystals, whereas n-GaN layers with similar carrier concentrations but containing C-compensation, as in the case of those grown by MOCVD, exhibited a severe mobility collapse (μ = 288 cm2/V s). High uniformity in the carrier concentration with a small standard deviation of 4.0% was observed in a 2-in. n-GaN wafer grown by QF-HVPE on a GaN substrate with an off-angle variation of 0.3°. On the other hand, the standard deviation of the carrier concentration in wafers grown by MOCVD was approximately 17% because of the off-angle-dependent C-incorporation.

中文翻译：

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通过无石英氢化物气相外延生长无碳诱导迁移率坍塌和偏角相关掺杂变化的 n-GaN 层的同质外延生长

由于不可避免的 C 诱导载流子补偿，在通过金属有机化学气相沉积 (MOCVD) 生长的 n-GaN 层中观察到某些不希望的现象。它们是载流子迁移率的急剧降低，称为迁移率崩溃，并且由于工艺的 C 结合效率的偏角依赖性，载流子浓度显着不均匀。这些现象对于 1015 到 1016/cm3 之间的低掺杂水平尤其严重，这适用于制造在几千伏到几十千伏范围内工作的垂直型 GaN 功率器件中使用的漂移层。然而，在我们最近开发的无石英氢化物气相外延 (QF-HVPE) 生长的同质外延 n-GaN 层中不存在与 C 相关的不良特性。使用无 C 原材料和无石英部件可以生长高纯度 GaN 晶体，其中 Si、C 和 O 的掺入可忽略不计。这些晶体的电子浓度在 1015/cm3 的低范围内，在 GaN 晶体中报告的最高室温电子迁移率 μ 为 1470 cm2/V s，而 n-GaN 层具有相似的载流子浓度但包含 C-补偿，与通过 MOCVD 生长的那些一样，表现出严重的迁移率崩溃 (μ = 288 cm2/V s)。在 2 in. 中观察到载流子浓度的高度均匀性，标准偏差为 4.0%。使用 QF-HVPE 在 GaN 衬底上生长的 n-GaN 晶片，偏角变化为 0.3°。另一方面，