In this paper, we present a compact model for undoped short-channel cylindrical surrounding-gate MOSFETs. The drain-current model is expressed as a function of the mobile charge density, which is calculated using the analytical expressions of the surface potential and the difference between surface and center potentials model. The short-channel effects are well incorporated in the drain-current model, such as the drain-induced barrier lowering, the charge sharing effect (VT Roll-off), the subthreshold slope degradation, and the channel length modulation. A comparison of the model results with 3D numerical simulations using Silvaco Atlas-TCAD presents a good agreement from subthreshold to strong inversion regime and for different bias voltages.

In this paper, we study the effects of short channel on double gate MOSFETs. We evaluate the variation of the threshold voltage, the subthreshold slope, the leakage current and the drain-induced barrier lowering when channel length LCH decreases. Furthermore, quantum effects on the performance of DG-MOSFETs are addressed and discussed. We also study the influence of metal gate work function on the performance of nanoscale MOSFETs. We use a self-consistent Poisson-Schrödinger solver in two dimensions over the entire device. A good agreement with numerical simulation results is obtained.

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Small-pitch, thin 3D Si sensors have been developed for the ATLAS and CMS experiment upgrades at the High Luminosity LHC. The pixel sizes are 50 × 50 µm2 with 1 readout column, and 25 × 100 µm2 with 1 or 2 readout columns (1E and 2E). Owing to the small inter-electrode distance, ranging from ∼28 µm to ∼51 µm in the considered layouts, these devices are expected to be extremely radiation hard. TCAD simulations by Synopsys Sentaurus, incorporating advanced radiation damage models, have been used for the design/optimization of these new 3D pixel sensors. In this study, we have compared the accuracy of different bulk damage models in predicting the signal efficiency of small-pitch 3D sensors irradiated at large fluences and its evolution with the bias voltage at different positions within the 3D cell. Selected simulation results will be reported in comparison to experimental data.