Silicon based mesa heterojunction photodetector

Silicon (Si) based photodetectors have been widely used in numerous applications due to their low-cost, high efficiency and good process compatibility. In this paper, a photodetector based on Si mesa heterojunction is reported. Si was doped by ion implantation and used to fabricate a photodetector. The conditions of ion implantation were simulated using a software to obtain the required process parameters before the commencement of the implantation process. The process involved deposition of 100 nm SiO2 film on to the Si substrate, and B ions were injected with 160 keV energy, 6×1014 cm-2 injection dose and at 7° dip angle. After ion implantation, the material was annealed at 900 ℃ for 30 min to repair crystal damages and activate the impurity level. Subsequently, a Si-based mesa heterojunction photodetector was fabricated using a series of standard processes. The photosensitive area of each device unit was 2.04 × 10-2 mm2 . The responsivity of the photodetector in the near ultraviolet and visible bands was more than 0.14 A/W under the bias of -2V. The responsivity of the device was measured using a 1073 K blackbody source, and the voltage responsivity of the blackbody was 1.35×102 V/W. Results from the C-V measurements revealed that the Si has a carrier concentration in the order of 1019 cm-3, which is in good agreement with the simulated results. The experimental results showed that ion implantation has an important effect on the electronic properties of the material and can greatly improve the photoelectric properties of devices.