Passivation of oxide traps and interface states in GaAs metal-oxide-semiconductor capacitor by LaTaON passivation layer and fluorine incorporation

Abstract

GaAs metal-oxide-semiconductor capacitor with TaYON/LaTaON gate-oxide stack and fluorine-plasma treatment is fabricated and compared with its counterparts without the LaTaON passivation interlayer or the fluorine treatment. Experimental results show that the sample exhibits better characteristics: low interface-state density (8 × 1011 cm−2/eV), small flatband voltage (0.69 V), good capacitance-voltage behavior, small frequency dispersion, and small gate leakage current (6.35 × 10−6 A/cm2 at Vfb + 1 V). These should be attributed to the suppressed growth of unstable Ga and As oxides on the GaAs surface during gate-oxide annealing by the LaTaON interlayer and fluorine incorporation, and the passivating effects of fluorine atoms on the acceptor-like interface and near-interface traps.