Epitaxial ZnO gate dielectrics deposited by RF sputter for AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors. (6th December 2017)

• Record Type: Journal Article
• Authors: Yoon, Seonno; Lee, Seungmin; Kim, Hyun-Seop; Cha, Ho-Young; Lee, Hi-Deok; Oh, Jungwoo
• Is Part Of: Semiconductor science and technology. Volume 33:Number 1(2018:Jan.)
• Publication Date: 2017-12-06
• Subjects: AlGaN/GaN MOSHEMT -- RF sputter -- high K -- ZnO gate dielectric; Semiconductors -- Periodicals; 621.38152
• DOI: 10.1088/1361-6641/aa9b58
• Languages: English
• ISSNs: 0268-1242

Abstract

Abstract: Radio frequency (RF)-sputtered ZnO gate dielectrics for AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs) were investigated with varying O2 /Ar ratios. The ZnO deposited with a low oxygen content of 4.5% showed a high dielectric constant and low interface trap density due to the compensation of oxygen vacancies during the sputtering process. The good capacitance–voltage characteristics of ZnO-on-AlGaN/GaN capacitors resulted from the high crystallinity of oxide at the interface, as investigated by x-ray diffraction and high-resolution transmission electron microscopy. The MOS-HEMTs demonstrated comparable output electrical characteristics with conventional Ni/Au HEMTs but a lower gate leakage current. At a gate voltage of −20 V, the typical gate leakage current for a MOS-HEMT with a gate length of 6 μ m and width of 100 μ m was found to be as low as 8.2 × 10 −7 mA mm −1, which was three orders lower than that of the Ni/Au Schottky gate HEMT. The reduction of the gate leakage current improved the on/off current ratio by three orders of magnitude. These results indicate that RF-sputtered ZnO with a low O2 /Ar ratio is a good gate dielectric for high-performance AlGaN/GaN MOS-HEMTs.