A study of metal-oxide-semiconductor capacitors on GaAs, ln_(0.53)Ga_(0.47)As, InAs, and InSb substrates using a germanium interfacial passivation layer

摘要

In this letter, we present electrical characteristics of HfO_2-based metal-oxide-semiconductor capacitors (MOSCAPs) on n- and p-type GaAs, In_(0.53)Ga_(0.47)As, InAs, and InSb substrates, along with the effect of a thin germanium interfacial passivation layer. We found that MOSCAPs on all n-type substrates showed good C-V characteristics with small frequency dispersion (< 10% and < 200 mV). However, MOSCAPs on p-type GaAs and In_(0.53)Ga_(0.47)As substrates exhibited poor C-V characteristics implying severe Fermi level pinning, as has also been seen for p-type InP substrate. On the other hand, MOSCAPs on p-type InAs and InSb substrates, known as smaller bandgap materials, showed good C-V characteristics. We also present plausible mechanism for Fermi level pinning and interface characteristics.