| Abstract | Passivation of both cleaved GaAs(110) facets and wafers (both n and p types) was performed with different surface treatments including HF-etch of native oxide, passivation with an ammonium sulfide solution, passivation with hydrogen polysulfide, and passivation with a Si/S, Ge/S, or Si/Ge/S interface control layer. The interface state density was measured with capacitance–voltage (CV) measurements of metal–insulator–semiconductor capacitors fabricated on the passivated surfaces using remote plasma deposited silicon nitride as gate insulator. The interface structures of the capacitors were analyzed by x-ray absorption near-edge structure spectroscopy and x-ray photoemission spectroscopy. It was found that, while the passivation procedures with the sulfur compounds or a Si/S interface control layer did improve the CV data when compared with the HF oxide etch, the Si/Ge/S multilayer passivation technique led to the best CV results. By comparing the quasistatic and high frequency (1 MHz) CV data, we found that the minimum interface state density of the fabricated capacitors was about 10¹² eV⁻¹ cm⁻². The results were compared with those obtained from GaAs(100) and the difference was addressed with respect to the surface geometry and the electronic structures. |
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