Heterodyne detection at 10.6 um using quasi-planar metal-oxide-metal tunnel diodes

Novel high performance symmetrical metal-oxide-metal tunnel diodes (MOMTD's) in a quasi-planar configuration have been successfully fabricated and, for the first time, used as room temperature detectors for the heterodyne mixing of two CO2 lasers operating on the P14 line near λ = 10.6 um. Using these devices, we have achieved state-of-the-art NEP in the 4–6 × 10∼¹⁵ W/Hz and a D∗ above 1 × 10⁶ cm Hz^1/2/W. The junction area of these devices is in the 1–2 × 10⁻¹⁰ cm², the junction oxide thickness is in the 12–15 A range (which is derived from the device's metals by reactive plasma process), the junction potential barrier lies in the 0.4 to 0.6 ev, and the series resistance is in the 5–10 Ω range. These MOMTD's were fabricated on thermal SiO2 grown on silicon substrates. These devices are batch processed fabricated using a fully plasma dry etch technology. Using this technology made it possible to realize high performance, high reproducibility, high yield, and high reliability as well as the fabrication of cluster type detectors having n × m detector arrays ranging from 10 × 10 to 700 × 1000.