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 - semiconductor barrier height enhancement. A high quality SiO2 layer is developed via liquid phase deposition, a method which naturally leaves a doping-level fluorine residue in the SiO2. The addition of fluorine to enhance the Schottky barrier height (SBH) is first discussed. Experimental results are presented. 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 with regard to device threshold voltage uniformity. The SBH to n-gallium arsenide (GaAS) is found to be approximately 0.7 eV. Finally, the effective barrier height of the metal - insulator - semiconductor structure reached 1.03 eV after annealing. The enhancement of SBH has been attributed to the formation of these stable interface layers. A model for fluorine-enhanced SiO2 SBH enhancement is also presented. [copyright] 2001 American Institute of Physics