Application of back bias to interdigital-electrode structured diamond UV detector showing enhanced responsivity

[Display omitted] •An interdigital-electrode structured UV detector with back-contact is designed and fabricated on single crystal diamond.•Higher responsivity and higher detectivity were observed when the back electrode contact was activated.•The mechanism for the improved performance has been revealed by UV-vis transmittance test and electric field simulation. An interdigital electrode of 200-nm thickness, 160-μm spacing, and 160-μm width was fabricated on one side of a diamond fabricated by chemical vapor deposition. A gold contact of 200-nm thickness was deposited on the back side of the diamond. The back contact and one half of the interdigital electrode were connected by a switch. Higher responsivity and higher detectivity were observed when the back electrode contact was activated. The results of electrical field simulation showed that a stronger electrical field formed over the diamond region in the device with the back electrode than in that without the back electrode. This indicated that the detector performance improvement could be attributed to the higher carrier collection efficiency achieved with the back electrode, particularly under ultraviolet (UV) light at certain wavelengths, which have longer attenuation lengths in diamond. This structure could also be applied to UV detectors based on other wide-band-gap semiconductors.