Hyperdoping silicon for intermediate band photoconductivity

Intermediate band formation in silicon could lead the way for photodetection well below the Si band gap. By incorporating transition metals into Si at levels well above the solid solubility limit, intermediate band absorption can lead to photoconductivity induced by photons with less than the energy of the band gap. These supersaturated solutions can be fabricated using the method of ion implantation followed by pulsed laser melting. This concept has been demonstrated with Si hyperdoped with Au or Ti, but the photoresponse of detectors based on this idea have low quantum efficiency. Here we report on enhancements in the photoresponse of Si:Au and Si:Ti based detectors from varying the implantation and laser melting conditions, as well as the formation of high-quality Ohmic contacts.