Improved DC performance of AlGaN/GaN high electron mobility transistors using hafnium oxide for surface passivation

• Published in: Thin solid films 2007-03, Vol.515 (10), p.4369-4372
• Main Authors: Liu, Chang, Chor, Eng Fong, Tan, Leng Seow
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Gallium nitride; Hafnium oxide; HEMT; Passivation; Physics; Surface conductivity and carrier phenomena
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2006.07.103

Improved DC performance of AlGaN/GaN high electron mobility transistors (HEMTs) have been demonstrated using reactive-sputtered hafnium oxide (HfO 2) thin film as the surface passivation layer. Hall data indicate a significant increase in the product of sheet carrier concentration ( n s) and electron mobility ( μ n) in the HfO 2-passivated HEMTs, compared to the unpassivated HEMTs. This improvement in electron carrier characteristics gives rise to a 22% higher I Dmax and an 18% higher g mmax in HEMTs with HfO 2 passivation relative to the unpassivated devices. On the other hand, I gleak of the HEMTs decreases by nearly one order of magnitude when HfO 2 passivation is applied. In addition, drain current is measured in the subthreshold regime. Compared to the unpassivated HEMTs, HfO 2-passivated HEMTs exhibit a much smaller off-state I D, indicating better turn-off characteristics.