A comparative study of dynamic characteristics of asymmetrical ATT diodes based on various semiconductor materials with increasing band-gap energy

Abstract

Elemental and compound semiconductors, including wide band gap semiconductor SiC, are critically examined for high-power performance of IMPATT diodes at 94 GHz, in terms of efficiency, high-temperature operation and noise measure. Based on a new analysis applicable to a wide range of semiconducting materials and by using the available measured physical parameters, it is shown that wide band gap semiconductor, SiC, offer significant advantages compared to conventional Si and Ge for these applications. The new analysis uses peak electric field strength at avalanche breakdown, avalanche response time and noise-measure as critical material parameters for evaluating the quality of a semiconducting material for high-frequency, high-power operation of an IMPATT oscillator. The study show improvement by order of magnitude in the maximum breakdown electric field, four hundred fold improvement in the RF power output, and over all potential for successful operation beyond 600K for SiC W-band IMPATTs. The present study depicts the improvement in the efficiency by three orders of magnitude and avalanche response time by an order of amplitude of the IMPATT device, by replacing Si with SiC. The noise analysis shows that under similar operating condition, Si 0.5 Ge 0.5 IMPATT is less noisy device than its counterparts. Though SiC IMPATTs outclass Si IMPATTs in terms of RF power, efficiency, noise level of these two types of IMPATTs are comparable (~ 17 dB).