Affiliation:
1. Key Laboratory of Nano-Devices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (CAS) 1 , Suzhou 215123, People's Republic of China
2. Nano Science and Technology Institute, University of Science and Technology of China 2 , Suzhou 215123, People's Republic of China
3. School of Nano Technology and Nano Bionics, University of Science and Technology of China 3 , Hefei 230026, People's Republic of China
Abstract
A HfO2/Al2O3/AlN stack deposited in a plasma-enhanced atomic layer deposition system is used as the gate dielectric for GaN metal–insulator–semiconductor structures. Prior to the deposition, in situ remote plasma pretreatments (RPPs) with O2, NH3, and NH3–O2 (in sequence) were carried out. Frequency-dependent capacitance–voltage (C–V) measurements reveal that for all the RPP-treated samples, the interface trap density Dit was significantly reduced compared to the sample without RPP. In particular, the NH3-treated sample exhibits an extremely low Dit of ∼1011 cm−2·eV−1 from EC − 0.31 eV to EC − 0.46 eV. To characterize the interface traps at deeper levels, the transfer pulsed I–V measurement was employed further. In the energy range of EC − ET > 0.54 eV, the interface trap charge density Qit of various samples demonstrates the following order: NH3 RPP < NH3–O2 RPP < O2 RPP < without RPP. By adjusting multiple pulse widths, the Dit derived from the Qit result matches the C–V measurement precisely. Moreover, X-ray photoelectron spectroscopy analysis of the Ga 3d core-level indicates that NH3 RPP facilitates the conversion of Ga2O into GaN at high RF power of 2500 W, whereas O2 RPP mainly oxidizes GaN to relatively stable Ga2O3. Combined with the C–V and pulsed I–V measurements, it is confirmed that a strong positive correlation exists between Ga2O and the interface traps, rather than Ga2O3.
Funder
National Key Research and Development Program of China
National Natural Science Foundation of China
Key Research Program of Frontier Science, Chinese Academy of Sciences
Bureau of International Cooperation, Chinese Academy of Sciences
Jiangsu Provincial Key Research and Development Program
Natural Science Foundation of Jiangsu Province
Science and Technology Program of Suzhou
Basic and Applied Basic Research Foundation of Guangdong Province
Youth Innovation Promotion Association of the Chinese Academy of Sciences
Guangdong Province Key-Area R&D Program
Subject
Physics and Astronomy (miscellaneous)