Physical behaviour of pseudomorphic HEMTs at low temperatures

The analysis of high frequency parameters of pseudomorphic HEMTs (PM-HEMT) at cryogenic temperatures and different gate lengths 0.1 μm to 0.7 μm, compared to existing modeling data, points out the improvement of average carrier velocity transport at low temperatures, the larger relative importance of certain parasitic effects (lateral diffusion under the gate, fringe effects, electrostatic capacitances) when the temperature decreases while other parasitic elements decrease (access and gate resistances) and also the influence of DX type centers.