Abstract
Understanding the interfacial electronic characteristics of oxide/III-V and improving its electrical properties is one of the most critical issues for realizing the advanced III-V MOS devices. In this work, the growth of atomic-layer-deposition (ALD) onto fresh molecular-beam-epitaxy (MBE) grown GaAs epi-layer, uses XPS to interface chemical analysis and fabricate MOS capacitors for electrical properties research. In the first part, Al2O3 on GaAs (001) are used with two different reconstruction surfaces: As-rich (2×4) and Ga-rich (4×6). Both the C-V curve and Dit values show better behavior on Ga-rich surfaces than with As-rich surface samples. Based on the results of electrical measurement and XPS analysis, the amounts of AsOx and Ga-O-Al/Ga1+ play an important role in affecting the electrical properties. In the second part, varying the thickness (14, 8, 5, and 3nm) of ALD-Al2O3 on GaAs(001)-(4×6) obtained good electrical characteristics. The leakage current increased after the annealing of 5nm thickness Al2O3. XPS found that Ga3+ and AsOx were diffused to the oxide surface after RTP annealing at 550oC. Therefore, the growth of hetro-structures of Al2O3/ GaAs with thinner oxide has a difficulty in GaAs devices. In part three, we researched properties of HfO2/GaAs interfaces with TMA exposure. The result showed that high-quality interfacial characteristics were attained by in-situ ALD-HfO2 passivation on GaAs surfaces, however the TMA exposure is not a strong difference for HfO2 in-situ growth on GaAs surfaces.