Study of Interface Traps in AlGaN/GaN MISHEMTs Using LPCVD SiNx as Gate Dielectric
Study of Interface Traps in AlGaN/GaN MISHEMTs Using LPCVD SiNx as Gate Dielectric
复制标题
使用 LPCVD SiNx 作为栅极电介质的 AlGaN/GaN MISHEMT 中界面陷阱的研究
DOI：
10.1109/ted.2017.2654358
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发表时间：
2017-03-01
影响因子：
3.1
通讯作者：
Lau, Kei May
中科院分区：
文献类型：
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作者：
Lu, Xing;Yu, Kun;Lau, Kei May
界面陷阱是限制GaN基MIS高电子迁移率晶体管（MISHEMT）器件性能的最臭名昭著的效应之一。在本文中，我们提出了一个全面的研究，在AlGaN/GaN MISHEMTs的界面陷阱使用低压化学气相沉积<sub>氮化硅作为</sub>栅极介质。结合MIS二极管和实际MISHEMT器件的陷阱分析，估算了界面陷阱态密度（<inline-formula><tex-math notation="LaTeX">$\text{D}_{\mathrm {it}}）$</tex-math></inline-formula>及其在器件中的分布，并研究了它们对器件电学性能的影响。两种类型的界面陷阱具有不同的发射时间常数，指定为“慢”和“快”的陷阱，被确定和其特征在于通过脉冲模式的电流-电压测量和频率依赖电导法。结果表明，采用等离子体增强化学气相沉积氮化硅<sub>钝化</sub>可以有效抑制器件接入区的“快”陷阱.然而，“慢”陷阱，无论是位于金属栅极下方或在访问区，受钝化的影响较小。对于横向GaN基MIS二极管，由于接入区陷阱的强烈干扰，采用传统的电导法提取<inline-formula><tex-math notation="LaTeX">的$\text{D}_{\mathrm {it}}$</tex-math></inline-formula>不准确。提出了一种修正的小信号等效电路，其中包括在接入区的陷阱的阻抗。当使用用于GaN基MIS器件的电导方法时，对器件访问区域进行适当的钝化是必不可少的。
Interface trapping is one of the most notorious effects that limit device performance in GaN-based MIS high electron mobility transistors (MISHEMTs). In this paper, we present a comprehensive study on interface traps in AlGaN/GaN MISHEMTs using low pressure chemical vapor deposition SiN<sub>x</sub> as gate dielectric. We combined the trapping analysis in MIS diodes and actual MISHEMTs to estimate the interface trap state densities (<inline-formula> <tex-math notation="LaTeX">$\text{D}_{\mathrm {it}})$ </tex-math></inline-formula> and their distributions in the device, and to investigate their influence on device electrical properties. Two types of interface traps with different emission time constants, designated as “slow” and “fast” traps, were identified and characterized by means of pulse-mode current-voltage measurements and a frequency dependent conductance method. It was found that “fast” traps located in the device access region could be effectively restrained by passivation using plasma enhanced chemical vapor deposition SiN<sub>x</sub>. However, “slow” traps, no matter whether located beneath the metal gate or in the access region, were less influenced by passivation. Due to the strong interference of traps in the access region, <inline-formula> <tex-math notation="LaTeX">$\text{D}_{\mathrm {it}}$ </tex-math></inline-formula> extraction using the conventional conductance method was not accurate for the lateral GaN-based MIS diodes. A modified small-signal equivalent circuit that includes the impedance of traps in the access region is proposed. Proper passivation for the device access region is essential when using the conductance method for GaN-based MIS devices.