Impact of InGaAs surface nitridation on interface properties of InGaAs metal-oxide-semiconductor capacitors using electron cyclotron resonance plasma sputtering SiO2

We perform InGaAs surface nitridation using electron cyclotron resonance (ECR) plasma and study the effect on interface properties of ECR-sputtered SiO2/InGaAs metal-oxide-semiconductor (MOS) capacitors. We demonstrate that the InGaAs surface nitridation, combined with in situ ECR SiO2 sputtering and annealing, effectively reduces the interface state density (Dit) of SiO2/InGaAs MOS capacitors and realizes a minimum Dit value of as low as 2×1011 cm−2 eV−1. It is found from x-ray photoelectron spectroscopy (XPS) analyses of the MOS interfaces that the MOS interfaces have almost no As oxides and that the nitridation and the subsequent annealing can reduce Ga oxides of InGaAs surfaces and form Ga–N bonds at the surfaces. It is suggested from the comparison in C-V and XPS data with and without nitridation that the Ga–N bond formation can be a key for the reduction in Dit, in addition to the suppression of Ga oxides and As oxides.