Electrical and noise properties of proton irradiated 4H-SiC Schottky diodes

The current voltage characteristics and the low-frequency noise in high voltage 4H-SiC junction barrier Schottky diodes irradiated with high energy (15 MeV) protons were studied at different temperatures and irradiation doses Phi from 3 x 10(12) cm(-2) to 1 x 10(14) cm(-2). Irradiation led to the increase of the base resistance and the appearance of slow relaxation processes at small, V <= 0.2 V, and at rather high, V >= 2V, forward voltages. The characteristic times of these relaxation processes ranged from similar to 1 mu s to 10(3) s. The exponential part of the current-voltage characteristic was only weakly affected by irradiation. The temperature dependence of the base resistance changed exponentially with temperature with activation energy E-a similar to 0.6 eV, indicating that the Z(1/2) level plays a dominant role in this process. The temperature increase also led to the increase of the ideality factor from 1.05 at 25 degrees C to 1.1 at 172 degrees C. At elevated temperatures and high forward voltages V>2-4 V, the current voltage characteristics tend to be super-linear. It is concluded that at high voltages, the space charge limited current of majority carriers (electrons) and hole injection from the p-n regions play an important role in the formation of the current voltage characteristic. The frequency dependences of noise spectral density S of proton irradiated Schottky diodes have the unusual form of S similar to 1/f(0.5). Published by AIP Publishing.