We analyzed the C-V curves of CdхHg1-хTe-based (x ∼ 0.22) MIS structures with Al2O3 as an insulator. Alumina films were deposited on p and n type CdхHg1-хTe by atomic layer deposition. C-V curve specific features at high and low frequencies were found to be a result of the semiconductor-dielectric interface surface state influence. The surface state density was derived from the fitting experimental C-V curves at high and low frequencies with the theoretical model. The calculated curves were obtained by solving Poisson and continuity equations within the drift-diffusion model. The charge exchange between the surface states and permitted bands was supposed to be conducted using the Shockley-Read-Hall mechanism.
In this letter, we present structural, compositional, and electrical characteristics of anodic oxide layer-based metal-oxide-semiconductor (MOS) capacitors on n-type InAs(111)A, along with the effect of a thin fluorinated interfacial passivation layer. Electrochemical oxidation in acid electrolyte with addition of fluorine (NH4F) led to the formation of oxygen free well-ordered wide gap fluorinated interfacial layer at InAs(111)A with the fixed charge (Qfix) and density of interface states (Dit) in the range of (4–6) × 1010 cm−2 and (2–12) × 1010 eV−1 cm−2, respectively. We found that MOS capacitors showed excellent capacitance-voltage characteristics with very small frequency dispersion (<1% and <15 mV). Fluorinated interfacial layer consists of crystalline isostructural compound with the InAs substrate, which remains intact with the atomic smoothness and sharpness that explain unpinned behavior of the Fermi level.
The influence of electron energy quantization in a space-charge region on the accumulation capacitance of the InAs-based metal-oxide-semiconductor capacitors (MOSCAPs) has been investigated by modeling and comparison with the experimental data from Au/anodic layer(4-20 nm)/n-InAs(111)A MOSCAPs. The accumulation capacitance for MOSCAPs has been calculated by the solution of Poisson equation with different assumptions and the self-consistent solution of Schrödinger and Poisson equations with quantization taken into account. It was shown that the quantization during the MOSCAPs accumulation capacitance calculations should be taken into consideration for the correct interface states density determination by Terman method and the evaluation of gate dielectric thickness from capacitance-voltage measurements.
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