Which of the following best describes the function of reverse bias in photo diodes?

The function of reverse bias in photo diodes is primarily related to the enhancement of the performance of the device, particularly regarding the generation and movement of electron-hole pairs. When a photo diode is reverse-biased, the depletion region widens, which increases the electric field within the diode.

This electric field plays a crucial role in efficiently separating the electron-hole pairs that are generated when light enters the diode. As photons are absorbed, they create electron-hole pairs; the strong electric field, established by the reverse bias, helps to quickly sweep these carriers (electrons and holes) towards their respective electrodes. This process leads to a more efficient conversion of light into electrical current, thereby enhancing the overall response of the photo diode to incoming light.

The other options do not align with the primary purpose of reverse bias. While reverse bias does indeed impact junction capacitance, its main role is not to reduce capacitance but to optimize the electric field for carrier separation. Reverse bias also does not promote electron recombination; instead, it works against this process by encouraging the movement of charge carriers away from the junction. Lastly, while reverse bias might influence the penetration of light marginally due to device structure, it is not designed to prevent light penetration but to enhance the diode