In this thesis, we demonstrate a high-performance Si–SiGe-based vertical-illuminated avalanche photodiode (APD) operating in the 830-nm wavelength regime. Under avalanche operation, the low-frequency roll-off caused by the slow diffusion current from the n+ silicon substrate can also be minimized. Also, our device can achieved high bandwidth due to impact-ionization-induced resonant effect. So, a wide bandwidth (15.3 GHz) and an extremely high gain-bandwidth (428 GHz) can be achieved simultaneously in our device without using complex silicon-on-insulator or germanium-on-insulator substrates.