PIN photodiode having a wide bandwidth

A PIN photodiode comprising a p region (102) containing a p type dopant, an n region (104) containing an n type dopant, an i region (106) positioned intermediate the p region and the n region, and a relatively thick, undoped buffer region (122) positioned between the n region and the i region which substantially decreases the capacitance of the PIN photodiode such that the photodiode bandwidth is maximized. Typically, the i region is formed as a layer of indium gallium arsenide (InGaAs) that is approximately 2.5 mu m to 3 mu m in thickness and the buffer region is formed as a layer of indium phosphide (InP) that is approximately 0.5 mu m to 2.5 mu m in thickness.