Jo Nylander

Complementary Si MESFET concept using silicon-on-sapphire technology

Complementary Si MESFETs (CMES) for integrated circuits using silicon-on-sapphire are described. Not only the gate, but also the source and drain of the n-transistors and p-transistors are Schottky junctions, using very high barrier heights for the gate and low barrier heights for source and drain. Only two Schottky metals are used: one, Ir or Pt, giving a high barrier on nSi, and hence low on pSi; the other, Er or Tb, showing the opposite behavior. The basic differences between MES and MOS are pointed out and design criteria for CMES inverters using normally-off type transistors are given.<<ETX>>

Computer simulations of Schottky contacts with a non-constant recombination velocity

Abstract The problem of modeling Schottky contacts for computer-aided physical simulation is investigated. Boundary conditions using a current dependent carrier recombination velocity distribution are developed, and installed in the two-dimensional simulation program BAMBI.

BAMBI — A transient 2D-MESFET model with general boundary conditions including Schottky and current controlled contacts

Abstract Boundary conditions using a current-dependent carrier recombination velocity distribution are developed for modelling Schottky contacts by computer-aided physical simulation. In addition, a boundary condition in the form of an arbitrary linear combination of voltage and current at the contact is presented. Thus MESFET devices with simple circuits connected to device terminals can be simulated by solving additional equations. As an example the switching behaviour of a MESFET with a drain resistor is investigated.

Influence of silicon-sapphire interface defects on SOS MESFET behavior

Abstract Silicon MESFETs in silicon-on-sapphire SOS technology were studied and a comparison was made between simulated and measured I - V characteristics of normally-off transistors. The comparisons have shown that the effective conducting-channel depth is only 40% of the actual Si film thickness. A novel simulation approach to compensate for the lack of free carriers close to the sapphire interface is described. Results from measured transistors is presented together with simulated behavior, and also a comparison between simulated and experimental complementary MESFET (CMES) inverter behavior is done. The influence of interface defects on subthreshold current is also discussed.

A fast approach for calculations of silicon MESFET characteristics from SUPREM doping profiles

A simple and fast program for process development of silicon n- and p-channel MESFETs has been developed. The program is used for rapid extraction of electrical and geometrical device parameters. Doping concentration profiles as predicted by SUPREM are used as input data. The simulations are controlled by a very simple input file. Channel thickness, IV-characteristics, pinch-off voltage, threshold voltage etc. may quickly be deduced. The program accounts for velocity saturation and includes doping concentration dependent mobilities. Also the effects of series resistances and contact resistances are included in the calculations. A comparison with fabricated devices is made and the agreement is found to be good. Comparisons of CPU time and accuracy is made to a general 2-D simulation program. This 2-D software was found to give somewhat better agreement to measured device characteristics but at the expense of at least 100 times longer execution times.