Narrow Results

We present a simple yet accurate model describing current-voltage characteristics of GaN-HEMT power switches in presence of carrier trapping often referred to as current collapse. The model accounts for time-dependent changes in the source-gate and gate-drain resistances after application of high drain voltage. The model also has a regime describing ‘fast’ current voltage characteristics when the applied voltage swing occurs within a period of time much shorter than the characteristic trapping – detrapping times. The model is written in Verilog-A and can be implemented in SPICE-type circuit simulators.

Field effect transistors (FETs) in plasmonic regimes of operation could detect terahertz (THz) radiation and operate as THz interferometers, spectrometers, frequency-to-digital converters and THz modulators and sources. We report on the development of compact models for Si MOS (Metal-Oxide-semiconductor) and heterostructure-based plasmonic FETs (or TeraFETs) suitable for circuit design in the THz range and based on the multi-segment unified charge control model. This model accounts for the electron inertia effect (by incorporating segmented Drude inductances), for the ballistic field effect mobility, which is proportional to the channel length, for parasitic resistances and capacitances and for the leakage current. It is validated by comparison with experimental data and TCAD simulation results. The model can be used for simulation and optimization of sub-THz and THz detectors. Our simulations use up to 200 segments in the device channel. The results are also in good qualitative agreement with the hydrodynamic simulations. Applications of our model could dramatically reduce astronomical design costs of nanoscale VLSI reaching US$1.5 billion for the 3 nm technological node.

TeraFET arrays operating in plasmonic regimes could support the transition from 5G to 6G communication if the constituent TeraFETs operate in synchrony. Such arrays are plasmonic crystals supporting Bloch-like waves of electron density oscillations. The key issues are breaking symmetry and maintaining appropriate boundary conditions between the unit cells. The symmetry must be broken to choose the response polarity to detect the direction of the plasmonic instability growth for generating THz oscillations. The coherence of plasma waves propagating in individual cells of the plasmonic crystal results in continuous waves in the entire structure. Using the narrow stripes at the unit cell edges (called plasmonic stubs) could maintain such coherence. Another advantage of TeraFET arrays is the reduced effects of parasitic contact resistance. This advantage is even more pronounced in ring plasmonic structures used for converting THz radiation into a magnetic field (giant inverse Faraday effect).

We present a simple yet accurate model describing current-voltage characteristics of GaN-HEMT power switches in presence of carrier trapping often referred to as current collapse. The model accounts for time-dependent changes in the source-gate and gate-drain resistances after application of high drain voltage. The model also has a regime describing ‘fast’ current voltage characteristics when the applied voltage swing occurs within a period of time much shorter than the characteristic trapping – detrapping times. The model is written in Verilog-A and can be implemented in SPICE-type circuit simulators.