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In this article, we propose a novel optoelectronic band-to-band tunnel field effect transistor with a Si photo-gate, for multi-spectral sensing of near-infrared light in the wavelength range of 0.7 μm-1 μm. Based on the line tunneling approach, a drain current model has been developed to illustrate the device operating principle. The model incorporates the effect of photo-generation in the photo-gate in terms of the resulting photo-voltage. Good agreement with device simulation results indicates overall correctness of the developed model. The spectral response of the device has been studied in terms of its input and output characteristics, and the spectral sensitivity has been defined in terms of the change in current, in response to the change in the illumination wavelength. The proposed device can resolute closely spaced spectral lines (~100 nm) in the wavelength range of 0.7 μm-1 μm, due to the combined effects of steep average sub-threshold swing of ~19 mV/dec, over five current decades, and current modulation due to change in the tunnel path length, induced by the gating effect of the photo-generated carriers. Peak spectral sensitivity at an illumination intensity of 0.5 W/cm-2 is found to be 5.88 × 103, 2.14 × 103, and 3.56 × 102 corresponding to decrease in illumination wavelength from (1 μm to 0.9 μm), (0.9 μm to 0.8 μm), and (0.8 μm to 0.7 μm), respectively. The influence of different device parameters, on the spectral sensing performance of the device, is thoroughly investigated by TCAD simulations and through the developed model. [ABSTRACT FROM AUTHOR]

This article studies the impact of doping dependent carrier effective masses of the source/drain regions on transport properties of Si-nanowire field effect transistors within ballistic limit. The difference of carrier effective mass in channel and that in the source/drain regions leads to a misalignment of respective sub-bands and forms non-ideal contacts. Such non-idealities are incorporated by modifying the relevant self-energies which control the effective electronic transport from source to drain through the channel. Non-ideality also arises in the nature of local density of states in the channel due to sub-band misalignment, resulting to a reduction of drain current by almost 50%. The highest values of drain current, leakage current, and their ratio are obtained for the S/D doping concentrations of 3 × 1020 cm–3, 8 × 1020 cm–3, and 2 × 1020 cm–3, respectively, for the nanowire of length 10 nm and diameter of 3 nm. Interestingly, the maximum of sub-threshold swing, minimum of threshold voltage, and the maximum of leakage current are observed to be apparent at the same doping concentration. [ABSTRACT FROM AUTHOR]

The combined impact of process- and substrate-induced stress has been analyticallymodeled for a rectangular fin inserted into an insulator-on-silicon (IOS) substrate. Stress estimation and profiling are performed for different fractional insertion of the fin into the IOS substrate and the induced stress values are observed to saturate for ≥1/3 of the fin insertion. Therefore, a one-third of inserted Si fin is used to estimate the induced stress by following a standard FinFET process flow. Uniaxial compressive stress as high as 4.6 GPa has been obtained, and it has also been observed that the hole mobility can be enhanced to a significantly high value by judiciously choosing the gate dielectrics and fractional insertion of the fin. Thereby, the design of symmetric CMOS by using such mobility-enhanced p-FinFET is possible. Moreover, the current--voltage characteristics of such strain-engineered p-FinFETs exhibit improved drain-induced barrier lowering and subthreshold swing and ~45% enhancement of drain current. [ABSTRACT FROM AUTHOR]

In this paper, an analytical model of threshold voltage VT for globally strained Si/SiGe CMOS devices using a dual-channel architecture is proposed. Since band parameters modify VT, they are calculated and generalized for different Ge contents in a Si1-xGex film grown on relaxed Si1-xGex virtual substrates (x, y < 0.7). A model for predicting VT is then developed by considering device geometry and material properties, including band parameters, permittivity, and channel and substrate doping concentrations. VT lowering due to short-channel effects is included by incorporating a voltage-doping transformation. Accuracy of the model is verified by comparing the model with the results of technology computer-aided design simulations and experiments. The model provides a physical insight for the variation of VT for both n- and p-MOSFETs in a dual-channel architecture, and it can be generalized to be applicable to single-channel devices as well. [ABSTRACT FROM AUTHOR]

This paper presents a new semianalytical model for the energy dispersion of the holes in the inversion layer of pMOS transistors. The wave vector dependence of the energy inside the 2-D subbands is described with an analytical, nonparabolic, and anisotropic expression. The procedure to extract the parameters of the model is transparent and simple, and we have used the band structure obtained with the k ·p method to calibrate the model for silicon MOSFETs with different crystal orientations. The model is validated by calculating several transport-related quantities in the inversion layer of a heavily doped pMOSFET and by systematically comparing the results to the corresponding k · p calculations. Finally, we have used the newly developed band-structure model to calculate the effective mobility of pMOS transistors and compare the results with the experimental data. The overall computational complexity of our model is dramatically smaller compared to a fully numerical treatment (such as the k · p method); hence, our approach opens new possibilities for the physically based modeling of pMOS transistors. [ABSTRACT FROM AUTHOR]