Comparison of 4H-SiC Separate Absorption and Multiplication Region Avalanche Photodiodes Structures for UV Detection

We designed and fabricated silicon carbide (SiC) separate absorption multiplication region avalanche photodiodes (SAM-APDs) for UV detection in harsh environment applications. Two variations of device types were compared. Type I was designed to achieve reach-through (i.e. multiplication, charge, and absorption layers are depleted) prior to reaching high gain while Type II was designed not to achieve reach-through (i.e. only the multiplication region is depleted). It was found that both the dark current behavior and the responsivity were improved significantly by employing a nonreach-through design. According to preliminary measurements, the maximum quantum efficiency of the type II was ~70 % at the wavelength of 300 nm.