Output Power Improvement in MSM Photomixers by Modified Finger Contacts Configuration

A novel type of metal–semiconductor–metal (MSM) photomixers (PMs) with an improvement of output power and frequency bandwidth was fabricated and tested. The device active area with interdigitated MSM structure is divided into two smaller ones connected in series (“twin” configuration) and thus the capacitance is reduced by factor four while the responsivity is reduced only by factor two compared to the standard MSM design with the same area. This was verified by responsivity and transient photoresponse measurements on low-temperature-grown GaAs devices. The photomixing measurements yielded (2–3)-times higher output power of the twin PM than the power of the standard one in the whole frequency range from 200 GHz to 1.2 THz, which is in agreement with the calculations.