Comparison of HfAlO, HfO_2/Al_2O_3, and HfO_2 on n-type GaAs using atomic layer deposition

摘要

Different high-permittivity (high-k) gate dielectric structures of HfO_2, HfAlO, and HfO_2/ Al_2O_3 deposited on HF-etched n-GaAs using ALD have been investigated. It has been demonstrated that the stacked structure of HfO_2/Al_2O_3 has the lowest interface state density of 8.12 × 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 HfO_2.