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This paper experimentally reports the channel direction (θ), effective field (Eeff), 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 (μph) 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, μph dependence on T−1.8 suggests the suppression of intervalley phonon scattering at low T as in Si. Also, μph is found to increase with Eeff, 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.

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We report the operation of 12-nm-thick, (110)-oriented Ge-on-insulator p-channel metal–oxide–semiconductor field-effect transistors along <110> channel direction [(110)/<110> GOI pMOSFETs], fabricated by the Ge condensation technique. The device operation under the accumulation mode was observed with the back gate structure. (110)/<110> GOI pMOSFETs have exhibited 2.3 times higher effective hole mobility, comparing with (100)-oriented GOI control devices (µeffGOI(100)). Also, present devices have the hole mobility enhancement factor of 3.0 and 1.5 against the (100)-oriented Si universal hole mobility and the (110)-oriented Si-on-insulator (SOI) effective hole mobility, respectively. These results demonstrate the superior hole transport properties of (110)/<110> GOI pMOSFETs.

Mobility enhancement technologies have currently been recognized as mandatory for future scaled MOSFETs. In this paper, we review our recent results on the development of mobilityenhanced CMOS device structures using strained-Si/SiGe/Ge MOS channels and the carrier transport properties in those channels. It is shown, particularly, that uniaxial compressive strain and Ge channels are quite effective in pMOS performance enhancement, while uniaxial tensile strain is effective in nMOS performance.