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通过对GaN基异质结材料C-V特性中耗尽电容的比较,得出AlGaN/GaN异质结缓冲层漏电与成核层的关系.实验结果表明,基于蓝宝石衬底低温GaN成核层和SiC衬底高温AlN成核层的异质结材料比基于蓝宝石衬底低温AlN成核层异质结材料漏电小、背景载流子浓度低.深入分析发现,基于薄成核层的异质结材料在近衬底的GaN缓冲层中具有高浓度的n型GaN导电层,而基于厚成核层的异质结材料的GaN缓冲层则呈高阻特性.GaN缓冲层中的n型导电层是导致器件漏电主要因素之一,适当提高成核层的质量和厚度可有效降低GaN缓冲层的背景载流子浓度,提高GaN缓冲层的高阻特性,抑制缓冲层漏电.
Through the comparison of the depletion capacitances in the CV characteristics of GaN-based heterojunction materials, the relationship between the leakage of the AlGaN / GaN heterojunction buffer layer and the nucleation layer is obtained.The experimental results show that the GaN- The heterojunction material of high temperature AlN nucleation layer of the substrate is smaller than the low temperature AlN nucleation layer heterojunction material based on sapphire substrate, and the background carrier concentration is low.It is further analyzed that the heterojunction material based on the thin nucleation layer A high concentration of n-type GaN conductive layer in the GaN buffer layer near the substrate and a high-resistance characteristic of the GaN buffer layer based on the heterogeneous material of the thick nucleation layer The n-type conductive layer in the GaN buffer layer is One of the main factors leading to device leakage, the appropriate increase of the quality and thickness of the nucleation layer can effectively reduce the background carrier concentration of the GaN buffer layer, improve the high-resistance characteristics of the GaN buffer layer, and suppress the buffer layer leakage.