High-performance GaAs metal-oxide-semiconductor capacitor by using NbAlON as high-k gate dielectric

Abstract

A GaAs metal-oxide-semiconductor (MOS) capacitor using NbAlON as a gate dielectric with different Nb contents is fabricated. Experimental results show that the k value and crystallization temperature of the AlON dielectric can be improved by Nb incorporation, together with reduction in negative oxide charges. However, the interface quality and gate leakage become poorer as the Nb content increases, as confirmed by TEM and X-ray photoelectron spectroscopy results. Therefore, through comprehensively considering the advantages and disadvantages, the sample with a Nb/(Al+Nb) atomic ratio of 62.5% exhibits the best characteristics: high k value (23.3), low interface-state density (2.7 × 1012 cm−2/eV), small hysteresis (55 mV), small frequency dispersion, and low gate leakage current (2.66 × 10−5A/cm2 at Vfb + 1 V). By comparing with reported GaAs MOS devices with different high-k gate dielectrics, it can be suggested that NbAlON is a promising gate dielectric material to achieve excellent electrical performance for GaAs MOS devices.