We report on ammonia and plasma-assisted molecular beam epitaxy (NH₃-MBE and PAMBE) grown GaN layers with a low net carrier concentration (N_net). Growth parameters, such as growth rate, V–III ratio, and plasma power, were investigated on different substrates to study their impact on surface morphology and background doping levels using atomic force microscopy and capacitance–voltage (C–V) measurements, respectively. The elevated growth rates are especially interesting for vertical power switches, requiring very thick drift regions (over 10 μm) with low background concentrations. For our NH₃-MBE-grown layers, N_net shows an almost linear increase with the growth rate. Using a freestanding substrate and at a fast growth rate of 1.4 μm hr⁻¹, a N_net value as low as 1 × 10¹⁵ cm⁻³ was achieved. For samples grown via PAMBE, the lowest N_net among samples grown under a Ga adlayer was 2 × 10¹⁶ cm⁻³ for a growth rate of 0.32 μm h⁻¹ on a GaN-on-sapphire template. The results support the use of MBE for growing high-quality GaN material with reasonably fast growth rates maintaining low background doping levels for high-voltage vertical power electronic devices.

中文翻译：

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生长参数对氨和等离子体辅助分子束外延生长的 GaN 薄膜背景掺杂的影响用于高压垂直功率开关

我们报告了氨和等离子体辅助分子束外延（NH ₃ -MBE 和 PAMBE）生长的具有低净载流子浓度 (N _net ) 的GaN 层。生长参数，如生长速率、V-III 比和等离子体功率，在不同的基板上进行了研究，以分别使用原子力显微镜和电容-电压 (C-V) 测量研究它们对表面形态和背景掺杂水平的影响。升高的生长速率对于垂直功率开关特别有趣的，需要非常厚的漂移区（在10 μ M）具有低背景浓度。对于我们的 NH ₃ -MBE-grown 层，N _net显示随增长率几乎呈线性增长。使用独立式基板并以 1.4 μ m hr ^-1的快速生长速率，实现了低至 1 × 10 ¹⁵  cm ^-3的 N_净值。对于通过 PAMBE 生长的样品，在 Ga adlayer 下生长的样品中最低的 N _net为 2 × 10 ¹⁶  cm ^-3在 GaN-on-sapphire 模板上的生长速率为 0.32 μ m h ^-1。结果支持使用 MBE 来生长高质量 GaN 材料，其生长速率相当快，可保持高压垂直电力电子器件的低背景掺杂水平。