Operation of semiconductor junction diodes at very high frequencies

Abstract

The objective of this research was to investigate the a-c electrical characteristics of semiconductor junction diodes at very high and ultra high frequencies for various d-c biasing conditions. An investigation of the electrical characteristics of gas diffused semiconductor junctions under the influence of impinging electromagnetic radiation was performed. As a result of these investigations applications of junction diodes at high frequencies became apparent and were developed. The procedure followed was to perform an analysis resulting in the small signal high frequency a-c equivalent circuits for alloy, grown and PIN junction diodes. Then the effect of large signals on the equivalent circuits was studied, followed by experimental verification of the theo­ retical results using commercially available diodes. The reflection charac­ teristics of large area gas diffused PN junction diodes were analyzed. Applications of these semiconductor junction diodes at very high frequencies were invented, and operating systems were tested. It was predicted that an ideal semiconductor junction diode small signal a-c equivalent circuit was a current sensitive conductance when the diode was forward biased and an open circuit when reverse biased. A volt­ age dependent depletion layer capacitor placed in shunt with the ideal diode conductance and a shunt leakage conductance as well as a series ohmic body resistance are added to obtain the equivalent circuits of alloy, grown and PIN junction diodes. For alloy junction diodes the depletion layer capaci­ tance varies inversely as the square root of the applied voltage, while the series ohmic body resistance and the shunt conductance are negligible. The The grown junction depletion layer capacitance varies inversely as the cube