A study of metal-oxide-semiconductor capacitors on GaAs, In0.53Ga0.47As, InAs, and InSb substrates using a germanium interfacial passivation layer

• Published in: Applied physics letters Vol. 93; no. 6
• Main Authors: Kim, Hyoung-Sub, Ok, I., Zhang, M., Zhu, F., Park, S., Yum, J., Zhao, H., Lee, Jack C., Majhi, Prashant, Goel, N., Tsai, W., Gaspe, C. K., Santos, M. B.
• Format: Journal Article
• Language: English
• Published: 11-08-2008
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.2972107

In this letter, we present electrical characteristics of HfO2-based metal-oxide-semiconductor capacitors (MOSCAPs) on n- and p-type GaAs, In0.53Ga0.47As, 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 In0.53Ga0.47As 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.