Ultrahigh-quantum-efficiency and high-bandwidth nanowire array UTC-PDs working at 1064 nm

In this study, a nanowire array of uni-traveling-carrier photodiodes working at 1064 nm is designed and studied by coupled three-dimensional optoelectronic simulation. The reliability of the physical model is demonstrated by comparison to previously reported results. Then, the epitaxial layer thickness, nanowire diameter (D), and period of unit (P) are investigated to determine the bandwidth and quantum efficiency. The device exhibits a remarkable internal quantum efficiency of 93.9% with a very thin absorption-layer thickness, 2.18 times higher than its thin-film counterpart with equivalent thickness. The equivalent capacitance per unit area is 0.015 fF/µm2, and the 3-dB $$f_{tr}$$ reaches 19.9 GHz. The structure of the nanowire array, which can improve both quantum efficiency and high-speed performance, is of great significance to the development of high-quantum-efficiency, high-speed photodetectors used in free space optical communication system.