Supersaturated semiconductors for infrared radiation detection
We develop new technologies for the fabrication of infrared photodetectors with improved photoresponse in the short-wave (SWIR) and mid-wave (MWIR) infrared ranges, under uncooled (or thermoelectric cooling) operation. We focus on Si and Ge-based photodetectors, aiming for compatibility with CMOS microelectronics technology and low cost.
Supersaturating Si or Ge with deep level impurities allows to extend its absorption range into the IR region due to lower energy transitions involving the impurity levels. Room temperature (RT) sub-bandgap IR response for supersaturated Si has been demonstrated for different systems obtained by ion implantation followed by pulsed-laser melting (like Si:Ti, Si:V, Si:S or Si:Au) or flash lamp annealing (Si:Se). For the MWIR range we propose Ge based photodetectors, looking for working temperatures close to room temperature, as a lower cost alternative with easier CMOS integration possibilities. Besides, the proposed materials (Si and Ge) are also advantageous with respect to other technologies due to avoiding rare or contaminant elements, like In, Pb, Cd or Hg.