High-electric-field-stress-induced degradation of SiN passivated AlGaN/GaN high electron mobility transistors
Gu Wen-Ping(谷文萍)†, Duan Huan-Tao(段焕涛), Ni Jin-Yu(倪金玉), Hao Yue(郝跃)‡, Zhang Jin-Cheng(张进城), Feng Qian(冯倩), and Ma Xiao-Hua(马晓华)
School of Microelectronics, Xidian University, Xi'an 710071, China;Key Lab of Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, Xi'an 710071, China
Abstract AlGaN/GaN high electron mobility transistors (HEMTs) are fabricated by employing SiN passivation, this paper investigates the degradation due to the high-electric-field stress. After the stress, a recoverable degradation has been found, consisting of the decrease of saturation drain current $I_{\rm Dsat}$, maximal transconductance $g_{\rm m}$, and the positive shift of threshold voltage $V_{\rm TH}$ at high drain-source voltage $V_{\rm DS}$. The high-electric-field stress degrades the electric characteristics of AlGaN/GaN HEMTs because the high field increases the electron trapping at the surface and in AlGaN barrier layer. The SiN passivation of AlGaN/GaN HEMTs decreases the surface trapping and 2DEG depletion a little during the high-electric-field stress. After the hot carrier stress with $V_{\rm DS}=20$ V and $V_{\rm GS}=0$ V applied to the device for 10$^{4}$ sec, the SiN passivation decreases the stress-induced degradation of $I_{\rm Dsat}$ from 36% to 30%. Both on-state and pulse-state stresses produce comparative decrease of $I_{\rm Dsat}$, which shows that although the passivation is effective in suppressing electron trapping in surface states, it does not protect the device from high-electric-field degradation in nature. So passivation in conjunction with other technological solutions like cap layer, prepassivation surface treatments, or field-plate gate to weaken high-electric-field degradation should be adopted.
Received: 11 September 2008
Revised: 04 November 2008
Accepted manuscript online:
(Semiconductor-device characterization, design, and modeling)
Fund: Project
supported by the State Key Program of National Natural Science
Foundation of China (Grant No 60736033), the State Key Development
Program (973 Program) for Basic Research of China (Grant No
513270407) and the Advanced Research Foundation of China
Cite this article:
Gu Wen-Ping(谷文萍), Duan Huan-Tao(段焕涛), Ni Jin-Yu(倪金玉), Hao Yue(郝跃), Zhang Jin-Cheng(张进城), Feng Qian(冯倩), and Ma Xiao-Hua(马晓华) High-electric-field-stress-induced degradation of SiN passivated AlGaN/GaN high electron mobility transistors 2009 Chin. Phys. B 18 1601
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