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

A complete analysis of low-noise 0.1 μm gate AlInAs-GaInAs HEMT´s has been performed by using a semiclassical Monte Carlo simulation. The validity of the model has been checked through the comparison of the simulated results with static, dynamic and noise experimental measurements of real HEMTs. In order to reproduce the experimental results, we have included in the model 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 experimental 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 the HEMTs. The reliability of the simulator allows us to realize “computer experiments” which will make faster and cheaper the optimization process of the device design