Dissociation of Al2O3(0001) substrates and the roles of silicon and oxygen in n-type GaN thin solid films grown by gas-source molecular beam epitaxy
Dissociation of Al2O3(0001) substrates and the roles of silicon and oxygen in n-type GaN thin solid films grown by gas-source molecular beam epitaxy
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DOI：
10.1063/1.373608
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发表时间：
2000-05
影响因子：
3.2
通讯作者：
J. E. Nostrand;J. Solomon;A. Saxler;Q. Xie;D. C. Reynolds;D. Look
中科院分区：
文献类型：
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作者：
J. E. Nostrand;J. Solomon;A. Saxler;Q. Xie;D. C. Reynolds;D. Look
研究了氨分子束外延制备的无意掺杂和掺硅GaN薄膜。利用霍尔、二次离子质谱（SIMS）、光致发光和x射线数据分析了氮化镓外延膜的自掺杂来源，以确定n型背景电子浓度是杂质来源还是天然缺陷来源。我们利用温度相关的霍尔测量，在不同Si掺杂浓度的蓝宝石上生长了一系列2.0 μm厚的GaN（0001）薄膜，确定并量化了Si掺杂浓度与自由载流子浓度和迁移率之间的异常关系。SIMS用于确定氧是轻掺杂和未掺杂GaN薄膜中多余自由载流子的来源。此外，氧气的来源被确定为蓝宝石衬底在氮-蓝宝石界面处的解离。SiC在氮化物-碳化物界面处的解离也被观察到。最后，SIMS再次被用来展示如何利用Si掺杂来抑制氧从蓝宝石衬底扩散到GaN层。抑制的机制被认为是Si-O键的形成和随后Si-O配合物在GaN中的扩散系数大大降低。
Unintentionally doped and silicon doped GaN films prepared by molecular beam epitaxy using ammonia are investigated. Hall, secondary ion mass spectroscopy (SIMS), photoluminescence, and x-ray data are utilized for analysis of sources of autodoping of GaN epitaxial films in an effort to identify whether the n-type background electron concentration is of impurity origin or native defect origin. We identify and quantify an anomalous relationship between the Si doping concentration and free carrier concentration and mobility using temperature dependent Hall measurements on a series of 2.0-μm-thick GaN(0001) films grown on sapphire with various Si doping concentrations. SIMS is used to identify oxygen as the origin of the excess free carriers in lightly doped and undoped GaN films. Further, the source of the oxygen is positively identified to be dissociation of the sapphire substrate at the nitride-sapphire interface. Dissociation of SiC at the nitride-carbide interface is also observed. Finally, SIMS is again utilized to show how Si doping can be utilized to suppress the diffusion of the oxygen into the GaN layer from the sapphire substrate. The mechanism of suppression is believed to be formation of a Si–O bond and a greatly reduced diffusion coefficient of the subsequent Si–O complex in GaN.