Self-Cleaning and Electrical Characteristics of ZrO2 (HfO2)/GaAs MOS Capacitor Fabricated by Atomic Layer Deposition

The reduction of native oxides on GaAs substrates is studied by short time pulsing of the metal precursor for self-cleaning mechanism using atomic layer deposition (ALD) of Trimethyl aluminum (TMA). The short time pulsing of the TMA is effective for self-cleaning mechanism to reduce the GaAs native oxides. X-ray photoelectron studies demonstrated that the pulsed deposition of TMA in the range of 2 to 4s is the most effective way of cleaning the GaAs native oxides. Microscopic studies clearly demonstrate the sharp interface between dielectric/GaAs. GaAs based metal oxide semiconductor (MOS) capacitors were fabricated with ZrO2 and HfO2 gate dielectrics using ALD. The effect of growth temperature of dielectric films on GaAs was studied. The as deposited samples have a significant amount of fixed charge in the bulk of the gate dielectric and at dielectric/semiconductor (ZrO2 or HfO2/GaAs) interface, which causes the flat band shift and frequency dispersion.