Barrier height enhancement of Ag/n-GaAs and Ag/n-InP Schottky diodes prepared by P2S5/(NH4)(2)S-x and HF treatments

A method for surface passivation using both the phosphorus sulfide/ammonia sulfide [P2S5/(NH4)(2)S-x] solution and hydrogen fluoride (HF) solution has shown great effectiveness on the barrier height enhancement of Ag/n-GaAs a nd Ag/n-InP Schottky diodes. It is found that, even though the Ag/n-GaAs an d Ag/n-InP diodes were baked for 18 h at 300 degrees C, their Schottky barr iers could still reach as high as 1.1 and 0.95 eV, respectively. After the bare semiconductor substrates were bathed successively in P2S5/(NH4)(2)S-x and HF solutions and then shone by an ultraviolet light, the analysis with x-ray photoelectron spectroscopy indicates a possible formation of ultrathi n and stable sulfur fluoride or phosphorus fluoride layers on the substrate surfaces. The formation of these stable interface layers has been attribut ed to the enhancement of Schottky barrier heights. (C) 1999 American Instit ute of Physics. [S0021-8979(99)03623-3].