Role of Bias Voltage in Semiconductor Light detector

[ralden]

Good day!, today, i visited an Institute about Semiconductor devices, One characterization device (Reflectance Spectrometer) which used to determine the reflectance of the semiconductor materials. This device used Semiconductor detector to detect the reflected light from the sample, but I'm confused because they used bias voltage on that detector and i don't why, is it for amplification of the reflected light? or is it for efficiency of the detector? I'm interested on the atomic level behavior (like in behavior ofcharge carriers in valence band to conduction band) Thanks in advance.

 

[tech99]

Good day!, today, i visited an Institute about Semiconductor devices, One characterization device (Reflectance Spectrometer) which used to determine the reflectance of the semiconductor materials. This device used Semiconductor detector to detect the reflected light from the sample, but I'm confused because they used bias voltage on that detector and i don't why, is it for amplification of the reflected light? or is it for efficiency of the detector? I'm interested on the atomic level behavior (like in behavior ofcharge carriers in valence band to conduction band) Thanks in advance.

A photo diode is usually operated with reverse bias, so it is non conducting, and the photons create electron-hole pairs which are then swept to the anode and cathode. Quite a good Wiki article here.
https://en.wikipedia.org/wiki/Photodiode