Improved Electrical Properties and Reliability of GaAs Metal-Oxide-Semiconductor Capacitor by Using LaAlON Passivation Layer

Abstract

GaAs metal–oxide–semiconductor (MOS) capacitors with NbAlON gate dielectric are fabricated with LaAlON or LaON as interface passivation layer and compared with their counterpart without interface passivation layer. Experimental results show that improvements in electrical properties and reliability are achieved, especially for the sample with LaAlON passivation layer (the hygroscopicity of LaON is largely reduced by Al incorporation): relatively high k value (25.5), low interface-state density (6.8 × 1011 cm−2 eV−1), small flatband voltage (0.67 V), small hysteresis (45 mV), small frequency dispersion and low gate leakage (6.18 × 10−6 A cm−2 at Vfb + 1 V). These should be attributed to the suppressed growth of unstable Ga and As oxides on the GaAs surface and reduced in-diffusion of elements from the gate dielectric to the GaAs surface by the LaAlON passivation layer during gate-dielectric annealing.