Capacitance Voltage Measurements for Determining Base Widths in High Speed Switching Transistors.

The purpose of the report is to investigate the possibility of using capacitance-voltage C-V analysis for measuring base widths in high speed switching microwave transistors. To accomplish this a model is developed for the junctions of a bipolar microwave transistor. The planar process of manufacturing double diffused microwave transistors is analyzed, the junctions are approximated by step functions, and the C-V relationship developed. Then a computer program is developed that will draw a doping density profile from the C-V data. The limitations of the step function approximation are then discussed, and an attempt is made to quantize and minimize the errors. Several large test transistors and small microwave transistors are tested using differential high-frequency C-V analysis.