Comparative analysis of the millimeter wave performance of diamond based IMPATT diode with that of SiC (4H) IMPATT diode

Abstract

A detailed comparative analysis of the diamond semiconductor based DDR IMPATT devices in W-band has been carried out (normal and photo illuminated) through a simulation scheme. The simulation results reveal that an optimized unilluminated diamond IMPATT diode of efficiency 18.45% can be realized, whereas 4H-SiC IMPATT can have efficiency of 11.97%. Under optical illumination, the admittance and negative resistance values of the IMPATT diode degrade due to additional photo generated carriers. The negative conductance (-G) and total negative resistance (-Z_R) of the diamond based DDR IMPATT diode decrease by 7.03% and 8.5%, respectively when the diode is exposed to photo illumination whereas, for SiC based diode the decrements are 6.06% and 6.09%, respectively. Moreover under optical illumination, the quality factor (Q_p) of diamond IMPATT increases by 22.5% and it is only 6.5% for SiC based devices. Therefore, from the simulation work it is well established that, though the photosensitivity of 4H-SiC based IMPATT is better than its diamond counterpart the overall small signal performance of the illuminated diamond IMPATT degrades far more than SiC based devices due to very high reported carrier ionization rates in diamond. The simulation results also reveal the superiority of diamond based IMPATT device in terms of heat sink design in comparison to 4H-SiC based devices.