Comparison of HfAlO, HfO2/Al2O3, and HfO2 on n-type GaAs using atomic layer deposition

Different high-permittivity (high-k) gate dielectric structures of HfO2, HfAlO, and HfO2/Al2O3 deposited on HF-etched n-GaAs using ALD have been investigated. It has been demonstrated that the stacked structure of HfO2/Al2O3 has the lowest interface state density of 8.12 x 10(12)eV(-1) cm(-2) due to the self-cleaning reaction process, but the sample of HfAlO shows much better frequency dispersion and much higher dielectric permittivity extracted from the C-V curves. The investigation reveals that the electrical properties of gate dielectrics are improved by introducing alumina into HfO2. (C) 2016 Elsevier Ltd. All rights reserved.