Browsing by Author "Chen, Wan-Li"

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Effect of Strained k . p Deformation Potentials on Hole Inversion-Layer Mobility
(2013-04-01)
Chen, Ming-Jer
;
Lee, Chien-Chih
;
Chen, Wan-Li
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In the literature dedicated to strained p-type metal-oxide-semiconductor field-effect transistor inversion-layer mobility calculation via a k . p valence-band structure, three key strain-related material parameters, namely, the Bir-Pikus deformation potentials a(upsilon), b, and d, were widespread in magnitude. To improve such large discrepancies, in this paper, we conduct sophisticated calculations on < 110 >/(001) and < 110 >/(110) hole inversion-layer mobility for gigapascal-level uniaxial stresses along each of three crystallographic directions. The screening effect on surface roughness scattering is taken into account. We find that, to affect the calculated hole mobility enhancement, a(upsilon) is weak, b is moderate, and d is strong, particularly for the uniaxial compressive stress along the < 110 > direction. This provides experimental guidelines for an optimal determination of the primary factor, i.e., d, and the secondary factor, i.e., b, with the commonly used values for a(upsilon). The result remains valid for varying surface roughness parameters and models and is supported by recent first-principles and tight-binding calculations. Thus, the strained k . p valence-band structure with the optimized deformation potentials can ensure the accuracy of the calculated transport properties of 2-D hole gas under stress.
Probing Long-Range Coulomb Interactions in Nanoscale MOSFETs
(2013-12-01)
Chen, Ming-Jer
;
Chang, Li-Ming
;
Wei, Sih-Yun
;
Chen, Wan-Li
;
Yeh, Ting-Hsien
We have recently experimentally probed long-range Coulomb interactions due to plasmons in polysilicon gate of long-channel (1 mu m) MOSFETs. In this letter, we further probe those due to plasmons in the highly doped source and drain. Test vehicles include four more samples from the same manufacturing process but with small channel lengths (down to 33 nm). I-V's of devices are measured at two drain voltages of 0.05 and 1 V, in a temperature range of 292-380 K. Inverse modeling technique is applied to furnish calibrated doping profiles. The inversion layer electron effective mobility is thereby extracted, showing a decreasing trend with decreasing channel length. Such differences reflect more additional scatterers in the shorter devices. Mobility components limited by these additional scatterers are assessed using Matthiessen's rule. From the extracted temperature dependencies, we infer that the strength of source/drain plasmons increases with decreasing channel length. The errors of Matthiessen's rule are adequately dealt with. Corroborative evidence is given as well.