Demonstration of genuine surface inversion for the p/n-In0.3Ga0.7Sb-Al2O3 MOS system with in situ H2 plasma cleaning

Abstract

The results of an investigation into the impact of in situ H2 plasma exposure on the electrical properties of the p/n-In0.3 Ga0.7 Sb-Al2O3 interface are presented. Samples were processed using a clustered inductively coupled plasma reactive ion etching and atomic layer deposition tool. Metal oxide semiconductor capacitors were fabricated subsequent to H2 plasma processing and Al2O3 deposition, and the corresponding capacitance-voltage and conductance-voltage measurements were analyzed quantitatively via the simulation of an equivalent circuit model. Interface state (Dit) and border trap (Nbt) densities were extracted for samples subjected to the optimal process, with a minimum Dit of 1.73×1012 eV−1 cm−2 located at ∼110 meV below the conduction band edge and peak Nbt approximately aligned with the valence and conduction band edges of 3×1019 cm−3 and 6.5×1019 cm−3, respectively. Analysis of the inversion response in terms of the extraction of the activation energy of minority carriers in inversion (p-type) and the observation of characteristics that pertain to minority carriers being supplied from an external inversion region (n-type) unequivocally demonstrate that the Fermi level is unpinned and that genuine surface inversion is observed for both doping polarities.