Effect of Crystal Defects on Reverse I-V Characteristics of 4H-SiC APDs
In this work, we investigated the effect of crystal defects on reverse I-V characteristics of avalanche photodiodes (APDs) using electron-beam induced current (EBIC) mode of SEM. Two types of SiC APD structures (I and II) were fabricated using 2 inch p-doped substrates with n-doped epilayers and 3 inch n-doped substrates with p- and n- epilayers. Areas of the formed diodes were approximately 1 mm2. The devices without any kind of electrically active 3-D structural defects demonstrated breakdown voltages close to theoretical values, ~500 V for the APD Type I and ~1200 V for Type II APD. Stability of Type I devices was tested by applying a short pulse of high voltage (~800 V). EBIC images, taken prior to and after the failure test, showed new defects in the dislocation free area, which, presumably, were caused by thermal breakdown.
Robert P. Devaty, David J. Larkin and Stephen E. Saddow
S. I. Soloviev et al., "Effect of Crystal Defects on Reverse I-V Characteristics of 4H-SiC APDs", Materials Science Forum, Vols. 527-529, pp. 427-430, 2006