Channel direction, effective field, and temperature dependencies of hole mobility in (110)-oriented Ge-on-insulator p-channel metal-oxide-semiconductor field-effect transistors fabricated by Ge condensation technique

This paper experimentally reports the channel direction (theta), effective field (E-eff), and temperature (T) dependencies of hole mobility in (110)-oriented 12-nm-thick accumulation mode Ge-on-insulator (GOI) p-channel metal-oxide-semiconductor field-effect transistors (pMOSFETs) fabricated by the Ge condensation technique. It is found that, the hole mobility on (110)-oriented GOI surfaces increases with the channel direction tilted from < 100 > to < 110 > direction, in contrast to (100) -oriented conventional GOI surfaces. By low temperature measurements, the extracted phonon-limited mobilities (mu(ph)) of (110)-oriented GOI surfaces along < 110 > direction occupy 2.1 and 7.1 of enhancement against (100)-oriented GOI and Si surfaces, respectively, at any T. Through physical insights into the present analyses, mu(ph) dependence on T-1.8 suggests the suppression of intervalley phonon scattering at low T as in Si. Also, mu(ph) is found to increase with E-eff, which can be regarded as an inherent property of hole mobility on (110)-oriented Ge. By further analyses base on the definition of mobility, the effective mass can be a dominant factor for the mobility anisotropy on (110)-oriented GOI pMOSFETs. (C) 2011 American Institute of Physics. [doi:10.1063/1.3537919]