Silicon carbide photodiode with improved short wavelength response and very low leakage current

摘要

A silicon carbide photodiode exhibiting high short-wavelength sensitivity, particularly in the ultraviolet spectrum, and very low reverse leakage current includes a p type conductivity 6H crystalline substrate. A first p- silicon carbide crystalline layer is epitaxially grown on the body. A second n+ silicon carbide crystalline layer is epitaxially grown on the first layer and forms a p-/n+ junction with the first layer. A metallic upper contact layer is formed on a predetermined surface region of the second layer oppositely situated from the junction. The second layer is of a uniform minimum thickness, generally less than 1000 Angstroms, with a greater thickness, typically 3000-4000 Angstroms, beneath the predetermined surface region. The thicker portion of the second layer occupies less than 10% and generally less than 1% of the total second layer surface area. Hence optical sensitivity of the photodiode is essentially determined by the thinner portion of the second layer, while the thicker portion of this layer is made sufficiently large to prevent diffusion of upper contact layer metal into the vicinity of the junction during contact sintering or alloying operations.