Impact of the silicon-nitride passivation film thickness on the characteristics of InAlAs/InGaAs InP-based HEMTs

• Published in: Journal of the Korean Physical Society 2015, 66(6), , pp.1020-1024
• Main Authors: Zhong, Ying-Hui, Yang, Jie, Li, Xin-Jian, Ding, Peng, Jin, Zhi
• Format: Article
• Language: English
• Subjects: Mathematical and Computational Physics; Particle and Nuclear Physics; Physics; Physics and Astronomy; Theoretical; 물리학
• ISSN: 0374-4884; 1976-8524
• DOI: 10.3938/jkps.66.1020

In this research, the DC and RF characteristics for our own InAlAs/InGaAs InP-based high-electron-mobility transistors (HEMTs) with 0-nm, 50-nm, and 200-nm silicon-nitride (Si 3 N 4 ) passivation films have been investigated comprehensively and systematically. With increasing Si 3 N 4 passivation film thickness, the device exhibits an apparent improvement in the output conductance and a distinct drift of the pinch-off voltage toward a positive value. Especially, the device passivated by using a 50-nm Si 3 N 4 film demonstrates the highest extrinsic transconductance and channel current. The appeared changes of the DC properties can be interpreted as due to the passivationinduced positively-charged surface state increasing the sheet carrier density with the carrier mobility and parasitic resistance of device being deteriorated by long-time high-stress-intensity ion bombardment. Additionally, the degradations of the current-gain cutoff frequency ( f T ) and maximum oscillation frequency ( f max ) can be attributed to the drastically-increased parasitic capacitance and resistance induced by the passivation process. This work will be of great importance in fabricating InP HEMTs with high performances.