Avalanche Diodes with Low Temperature Dependence in 4H-SiC Suitable for Parallel Protection

Abstract

Avalanche diodes have been fabricated on 4H-SiC substrate. These diodes show an abrupt avalanche voltage of about 59 V which corresponds to the calculated theoretical one using our previously determined impact ionization coefficients. This avalanche voltage increases by as small as 3.7 mV/K over the investigated temperature range (150K-420K).

SIMS Analyses Applied to Open an Optical Window in 4H-SiC Devices for Electro-Optical Measurements

“…In Ref. [5] we have shown that the avalanche multiplication is the main breakdown mechanism in this kind of device and that the positive temperature coefficient is very weak. OBIC measurements have been performed on these diodes with an UV laser beam (351 nm) with a spot size of 3µm diffusing through the cratering formed by SIMS.…”

“…In Ref. [5] we have shown that the avalanche multiplication is the main breakdown mechanism in this kind of device and that the positive temperature coefficient is very weak.…”

“…Vertical bipolar power diodes have been fabricated on a commercial n + 4H-SiC substrate with an n-type drift and a top p-type anode-epilayer. Details on the fabrication process have been published elsewhere [5]. Ohmic contacts for the anode have been realized in two steps: first, by patterning followed by a rapid thermal annealing a 250 nm layer, based on Al, Ti and Ni, and secondly, by adding a 500 nm thick Al over-metallization on top of the contacts.…”

OBIC Measurements on Avalanche Diodes in 4H-SiC for the Determination of Impact Ionization Coefficients

“…The avalanche diodes used in this study show an abrupt avalanche breakdown voltage of about 59 V which is presented in detail in a previous paper [4]. To perform OBIC measurements, optical windows have been opened on the anode metallizations by using the Secondary Ion Mass Spectrometry (SIMS) technique [5].…”