There are 4 types of photodiode Avalanche Photodiode, PIN Photodiode, Schottky Photodiode and PN photodiode.
Avalanche Photodiode: Avalanche photodiode technology is used in areas of low light due to its high gain. In contrast, it generates a high noise level. Accordingly, this photodiode technology is not suitable for all applications.
PIN Photodiode: The PIN photodiode is one of the most commonly used types of photodiodes today. The PIN photodiode collects the light photons more efficiently than the standard PN photodiode, as more light can be collected through the large intrinsic region between the P and N regions, and also provides lower capacitance.
Schottky Photodiode: The Schottky Photodiode is based on the Schottky diode. The small diode junction means that there is very little junction capacitance, and this means that it can operate at high speeds. As a result, this form of photodiode is often used in high bandwidth optical communication systems, e.g. Fiber connections.
PN photodiode: The PN photodiode was the first developed photodiode form. The performance is not as high as some other types, so use is less today than it used to be.