Ge-on-Si Plasma-Enhanced Chemical Vapor Deposition for Low-Cost Photodetectors

The development of low-thermal-budget Ge-on-Si epitaxial growth for the fabrication of low-cost Ge-on-Si devices is highly desirable for the field of silicon photonics. At present, most Ge-on-Si growth techniques require high growth temperatures, followed by cyclic annealing at temperatures
$>800\ ^{\circ}\hbox{C} $
, often for a period of several hours. Here, we present a low-temperature (400
$^{\circ}{\rm C} $
) low-cost plasma-enhanced chemical vapor deposition (PECVD) Ge-on-Si growth study and, subsequently, fabricate a high-speed zero-bias 12.5-Gb/s waveguide integrated photodetector with a responsivity of 0.1 A/W at a wavelength of 1550 nm. This low-energy device demonstrates the feasibility of the PECVD method for the fabrication of low-cost low-thermal-budget Ge-on-Si devices.