Monte Carlo simulator for the design optimization of low-noise HEMTs

A complete analysis of low-noise 0.1 mu m gate AlInAs/GaInAs HEMT's has bee n performed by using a semiclassical Monte Carlo simulation. The validity o f the model has been checked through the comparison of the simulated result s with static, dynamic and noise experimental measurements of real HEMTs. I n order to reproduce the experimental results, we have included in the mode l some important real effects such as degeneracy, surface charges, T-shape of the gate, presence of dielectrics and contact resistances. Moreover, the extrinsic parameters of the devices have been added to the usual intrinsic small-signal equivalent circuit, thus allowing the calculation of the real noise of the HEMTs (characterized using the extrinsic minimum noise figure ), In this way, we make possible not only the comparison with the experimen tal noise results, but also the analysis of the influence of the parasitic elements, the device width or the number of gate fingers on the noise of th e HEMTs. The reliability of the simulator allows us to realize "computer ex periments" which will make faster and cheaper the optimization process of t he device design.