What is the semiconductor material for visible light photodetector preparation

Semiconductor silicon is one of the most desirable materials in the field of visible light detection, and it is also a commonly used material for ultraviolet photoelectric sensing. However, the silicon material has a low response to ultraviolet light, which is due to the ultraviolet light transmission depth in silicon material is very shallow (wavelength 370 nm or less, the transmission depth is greater than 20 nm), the photogenerated carriers are mainly concentrated on the surface of the silicon, and the traditional silicon-based P-N or P-I-N junction photodetector device junction depth is generally greater than 200 nm, the carrier composite effect leads to the optical response with the wavelength of the incident light The carrier complex effect leads to a rapid decrease in optical response with decreasing incident wavelength.

Ultra-shallow P-N or P-I-N junctions (depth greater than 20 nm) are quite difficult to prepare, and the traditional method is to prepare shallow junctions using ion implantation and precisely controlled thermal diffusion processes, but they are prone to form P+N junctions near the silicon surface, and the highly doped P+ region increases the carrier complexation on the surface and reduces the responsivity of the photodetector. Some newly developed shallow junction techniques (e.g., δ-doping or laser doping techniques) are quite complex to prepare, resulting in silicon-based photoelectric sensors becoming expensive.