Design and Fabrication of Si-based Photodetectors for Infrared Detection

Silicon photodetectors dominate the electronics market due to their high performance, low cost, maturity, and high level of integration with electronics. These are vastly used in consumer electronics, biomedical imaging, manufacturing process monitoring, etc. Unfortunately, infrared (IR) detection in Si photodetectors is limited due to the relatively large band gap of Si. The existing techniques beyond this range are based on InGaAs or HgCdTe, but these technologies are not compatible with Si which leads to high manufacturing costs. Thus Si-based IR detectors could be the most convenient alternative. One promising approach to solve the high band gap problem of Si is to introduce an intermediate band between the conduction band and valence band. Hyperdoped Si, as an intermediate band material, has been demonstrated to exhibit optical absorption well below the band gap of Si. In this work, we are exploring methods to design and fabricate waveguide-based photodetectors using hyperdoped Si to achieve efficient responsivity in the IR with devices integrated into Si. We fabricated a simple Si photodiode by using photolithography for patterning, metal deposition by E-beam evaporation, followed by lift-off to create contacts. These processes will be refined to produce waveguide structures for photodetectors. Our future goal is to fabricate hyperdoped Si-based photodetectors that will work in the infrared region with high-efficiency.