N. Cameron

Simple approach to include external resistances in the Monte Carlo simulation of MESFETs and HEMTs

The contact and external series resistances play an important role in the performance of modern 0.1-0.2 /spl mu/m HEMTs. It is not possible to include these resistances directly into the Monte Carlo simulations. Here we describe a simple and efficient way to include the external series resistances into the Monte Carlo results of the intrinsic device simulations. Examples of simulation results are given for a 0.2 /spl mu/m pseudomorphic HEMT.

New evidence for velocity overshoot in a 200 nm pseudomorphic HEMT

It is believed that significant velocity overshoot effects are responsible for the high performance of Pseudomorphic HEMTs (PsHEMTs) with InGaAs channels grown on GaAs substrates. The expected overshoot is associated with the low effective mass in the channel and the large ¿ - L separation and is clearly demonstrated in numerous Monte Carlo simulations. Average electron velocities well in excess of 3.0×107 cm/s have been predicted. However, average electron velocities extracted form transconductance measurements of such devices are much lower, typically in the range 1.5 - 2.0×107 cm/s. Although there are some explanations in the literature for why such discrepancies exist in the extracted effective velocity they are based on Monte Carlo simulation itself without direct links to real fabricated and measured devices. In this paper we analyse for the first time real device measurements by using Monte Carlo and drift diffusion simulations. We obtain clear evidence that the average velocity in the channel of 200 nm PsHEMT fabricated in the Nanoelectronics Research Centre of Glasgow University exceeds 3.0×107 cm/s.

Finite Element Simulation of Recess Gate MESFETs and HEMTs: The Simulator H2F

In this paper we present a new 2D finite element compound semiconductor device simulator H2F suited for simulation of the parasitic effects in recess gate MESFETs and HEMTS. Several simulation examples of real devices fabricated in the Nanoelectronics Research Centre at the University of Glasgow illustrates the usefulness of the adopted finite element approach.

Complete RF Analysis of Compound FETs Based on Transient Monte Carlo Simulation

In this paper we described a complete methodology to extract the RF performance of ‘real’ compound FETs from time domain Ensemble Monte-Carlo (EMC) simulations which can be used for practical device design. The methodology is based on transient finite element EMC simulation of realistic device geometry. The extraction of the terminal current is based on the Ramo-Shockley theorem. Parasitic elements like the gate and contact resistances are included in the RF analysis at the post-processing stage. Example of the RF analysis of pseudomorphic HEMTs illustrates our approach.