Ultraquasi-hydrodynamic electron transport in submicrometer field effect MIS transistors and heterotransistors

It is shown that electrons in the channel of submicrometer field effect tra nsistors have no time to be heated to quasi-steady-state temperatures corre sponding to a balance between the Joule heating and thermal relaxation. Thi s "underheating" contributes to an increase in the effective mobility of ch arge carriers as compared to the value of mu(E) corresponding to the drift- diffusion approximation. Using a reduction of the thermal-balance equation by eliminating the relaxation-related term, a simple analytical expression is obtained for current-voltage characteristics. In particular, the saturat ion current in the developed ultraquasi-hydrodynamic model is found to be p roportional to (V-G - V-t)(3/2). The results of measurements of characteris tics of the test GaAlAs/InGaAs/GaAs P-HEMTs with the channel length of abou t 0.3 mu m are reported; these results verify the adequacy of the developed model, the accuracy of which can only increase with a further decrease in the channel length. (C) 2000 MAIK "Nauka/Interperiodica".