Correlation between mobility collapse and carbon impurities in Si-doped GaN grown by low pressure metalorganic chemical vapor deposition
Correlation between mobility collapse and carbon impurities in Si-doped GaN grown by low pressure metalorganic chemical vapor deposition
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DOI：
10.1063/1.4962017
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发表时间：
2016-09-14
影响因子：
3.2
通讯作者：
Sitar, Zlatko
中科院分区：
文献类型：
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作者：
Kaess, Felix;Mita, Seiji;Sitar, Zlatko
在低于1 x 10(17) cm(-3)的低掺杂范围内，碳被认为是低压金属有机化学气相沉积生长的n型GaN中电子迁移率突然降低（即电子迁移率崩溃）的主要缺陷。二次离子质谱分析与 C 浓度和热力学 Ga 过饱和模型结合进行。通过控制氨流速、Ga前驱体的输入分压以及Ga过饱和模型中的稀释气体，Si掺杂GaN中的C浓度可从6 x 10(19)cm(-3)控制到低至2 x 10 15cm(-3)。研究发现，一旦 Si 浓度接近 C 浓度，电子迁移率就会随自由载流子浓度而下降。通过优化Ga过饱和度将C浓度降低至10(15) cm(-3)量级，实现了可控自由载流子浓度低至5 x 10(15) cm(-3)，峰值电子迁移率为820 cm(2)/V s，而没有观察到迁移率崩溃。通过优化 Ga 过饱和度方面的生长参数以降低 C 浓度，即使在蓝宝石衬底上有机金属气相沉积生长的 GaN 中，也可以获得 1170 cm(2)/V s 的最高电子迁移率。由 AIP 出版社出版。
In the low doping range below 1 x 10(17) cm(-3), carbon was identified as the main defect attributing to the sudden reduction of the electron mobility, the electron mobility collapse, in n-type GaN grown by low pressure metalorganic chemical vapor deposition. Secondary ion mass spectroscopy has been performed in conjunction with C concentration and the thermodynamic Ga supersaturation model. By controlling the ammonia flow rate, the input partial pressure of Ga precursor, and the diluent gas within the Ga supersaturation model, the C concentration in Si-doped GaN was controllable from 6 x 10(19) cm(-3) to values as low as 2 x 10 15 cm(-3). It was found that the electron mobility collapsed as a function of free carrier concentration, once the Si concentration closely approached the C concentration. Lowering the C concentration to the order of 10(15) cm(-3) by optimizing Ga supersaturation achieved controllable free carrier concentrations down to 5 x 10(15) cm(-3) with a peak electron mobility of 820 cm(2)/V s without observing the mobility collapse. The highest electron mobility of 1170 cm(2)/V s was obtained even in metalorganic vapor deposition-grown GaN on sapphire substrates by optimizing growth parameters in terms of Ga supersaturation to reduce the C concentration. Published by AIP Publishing.