Enhancement of metal-semiconductor barrier height with superthin silicon dioxide films deposited on gallium arsenide by liquid phase deposition

This study presents a method for surface passivation using silicon dioxide (SiO2). The proposed method has shown great effectiveness on metal-semicond uctor barrier height enhancement. A high quality SiO2 layer is developed vi a liquid phase deposition, a method which naturally leaves a doping-level f luorine residue in the SiO2. The addition of fluorine to enhance the Schott ky barrier height (SBH) is first discussed. Experimental results are presen ted. It is found that this fluorine addition enhances the Schottky barrier height, which allows a larger positive gate bias for enhancement mode metal -semiconductor field-effect transistors, thus permitting the fabrication of digital logic circuits with improved noise margins and relaxed tolerance w ith regard to device threshold voltage uniformity. The SBH to n-gallium ars enide (GaAS) is found to be approximately 0.7 eV. Finally, the effective ba rrier height of the metal-insulator-semiconductor structure reached 1.03 eV after annealing. The enhancement of SBH has been attributed to the formati on of these stable interface layers. A model for fluorine-enhanced SiO2 SBH enhancement is also presented. (C) 2001 American Institute of Physics.