To realize high-mobility surface channel pMOSFETs on Ge, a 1.6-nm-thick SiOX passivation layer between the bulk Ge substrate and HfSiO gate dielectric was introduced. This approach provides a simple alternative to epitaxial Si deposition followed by selective oxidation and leads to one of the highest peak hole mobilities reported for unstrained surface channel pMOSFETs on Ge: 332 cm2 middotV-1middots-1 at 0.05 MV/cm-a 2times enhancement over the universal Si/SiO2 mobility. The devices show well-behaved output and transfer characteristics, an equivalent oxide thickness of 1.85 nm and an ION/IOFF ratio of 3times103 without detectable fast transient charging. The high hole mobility of these devices is attributed to adequate passivation of the Ge surface
[Show abstract][Hide abstract] ABSTRACT: Ge Metal–Oxide–Semiconductor (MOS) capacitors with LaON gate dielectric incorporating different Ti contents are fabricated and their electrical properties are measured and compared. It is found that Ti incorporation can increase the dielectric permittivity, and the higher the Ti content, the larger is the permittivity. However, the interfacial and gate-leakage properties become poorer as the Ti content increases. Therefore, optimization of Ti content is important in order to obtain a good trade-off among the electrical properties of the device. For the studied range of the Ti/La2O3 ratio, a suitable Ti/La2O3 ratio of 14.7% results in a high relative permittivity of 24.6, low interface-state density of 3.1×1011 eV−1 cm−2, and relatively low gate-leakage current density of 2.0×10−3 A cm−2 at a gate voltage of 1 V.
Applied Physics A 06/2010; 99(4). DOI:10.1007/s00339-010-5665-5 · 1.70 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The valence band structure and hole effective mass of Germanium under uniaxial  stress were investigated by using six-band k⋅p theory coupled with deformation potential theory. The valence band edge energy level shifting, splitting, and effective mass change were calculated for different uniaxial  stress configurations. The results show that the degenerate of valence band edge energy levels was lifted and the shape of valence bands was distorted in comparison to unstressed case. The effective mass for the top band along the  direction is the lowest compared with other directions under uniaxial  compressive stress. The isotropic effective masses for the top and second bands in unstressed case, our calculated results show good agreement with the available experimental values. The obtained splitting energy between the top and the second bands, direction effective mass, and isotropic effective mass can provide valuable reference for the calculation of other physical parameters of uniaxial stressed Germanium.
[Show abstract][Hide abstract] ABSTRACT: The electrical properties and high-field reliability of HfTa-based gate-dielectric metal–oxide–semiconductor (MOS) devices
with and without AlON interlayer on Ge substrate are investigated. Experimental results show that the MOS capacitor with HfTaON/AlON
stack gate dielectric exhibits low interface-state/oxide-charge densities, low gate leakage, small capacitance equivalent
thickness (∼1.1nm), and high dielectric constant (∼20). All of these should be attributed to the blocking role of the ultrathin
AlON interlayer against interdiffusions of Ge, Hf, and Ta and penetration of O into the Ge substrate, with the latter effectively
suppressing the unintentional formation of unstable poor-quality low-k GeO
and giving a superior AlON/Ge interface. Moreover, incorporation of N into both the interlayer and high-k dielectric further improves the device reliability under high-field stress through the formation of strong N-related bonds.
Applied Physics A 04/2009; 99(1):177-180. DOI:10.1007/s00339-009-5480-z · 1.70 Impact Factor
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