Interface state densities for SiNx:H on cleaved GaAs and InP(110)

Silicon nitride was deposited in-situ by electron-cyclotron resonance plasma chemical-vapour deposition (ECR-CVD) on (110) surfaces formed by cleaving GaAs and InP(100) substrates in an ultra-high vacuum processing system. Capacitors formed by depositing Al gates on the facet surfaces were analyzed by the high-low frequency capacitance-voltage (CV) technique. The minimum interface-state densities obtained for the cleaved GaAs (110) surfaces were 1-2 x 10(12) eV(-1)cm(-2). For cleaved InP facets the measured minimum interface state densities were a factor of two higher; however, they exhibited a smaller hysteresis in the CV characteristics and a smaller modulation in the surface potential. The interface state densities did not change significantly for the GaAs(110) facets if a Si interface control layer 0.8-2 nm thick was deposited prior to silicon nitride deposition; however, a larger effect was observed for the hysteresis and flatband voltage shift of the CV characteristics. The effect of annealing on the interfaces with Si was investigated and the performance compared with published results for GaAs(100) surfaces prepared by molecular-beam epitaxy.