Showing papers by "Liang Ding published in 2012"

310 GHz gain-bandwidth product Ge/Si avalanche photodetector for 1550 nm light detection.

Abstract: We report a normal incidence Ge/Si avalanche photodiode with separate-absorption-charge-multiplication (SACM) structure by selective epitaxial growth. By proper design of charge and multiplication layers and by optimizing the electric field distribution in the depletion region to eliminate germanium impact-ionization at high gain, a high responsivity of 12 A/W and a large gain-bandwidth product of 310 GHz have been achieved at 1550 nm.

Ge waveguide photodetectors with responsivity roll-off beyond 1620 nm using localized stressor

Abstract: We report a novel Ge waveguide photodetector and the fabrication on silicon-on-insulator (SOI) platform. Localized stressor structures were incorporated to tune the responsivity roll-off wavelength. With the localized stressor structure, the roll-off in responsivity is found to be red-shifted from 1520 nm to beyond 1620 nm, i.e., a flat responsivity over the entire C- and L-band is obtained. This technique makes Ge a promising material for fabricating monolithic high-responsivity receivers covering the entire C- and L-band fiber optic communications.

Dependences of photoluminescence from P-implanted epitaxial Ge.

Abstract: A systematic investigation has been carried out to study the influence of various annealings and implantations on the photoluminescence (PL) properties of phosphorus (P)-implanted Ge epitaxial films on Si substrate. For un-capped Ge samples, rapid thermal annealing (RTA) at 700 °C for 300 seconds yields the strongest PL emission peaked at 1550 nm. The influence of employing various capping layers (i.e., SiO2, Si3N4, and α-Si) on the PL properties has been investigated. The capping layers are found to effectively decrease the dopant loss, leading to a significant PL enhancement. Si3N4 is found to be the most efficient capping layer to prevent dopant out-diffusion and thus lead to strongest PL. Furthermore, it has been found that capping layers not only enhance the PL intensities but also make PL emission peak red- and blue- shift, depending on the stress type of the capping films. The effect of implantation dose on the PL has been also investigated.

A nano-optical switch driven by optical force using a laterally coupled double-ring resonator

Abstract: This paper reports a nano-optical switch driven by optical force in a laterally coupled double-ring resonator. The nano-switch consists of two bus waveguides and a double-ring resonator, with one ring suspended. The circulating power in the double-ring resonator generates strong optical force, leading to deformation of the suspended ring. As a result, a resonance shift at the output leads to the switching operation. In experiment, a switching contrast of more than 25 dB is achieved, with a switching time of nano-seconds. Compared with other reported free-carrier effect and/or silicon-based high speed switches, the proposed switch allows switching operation at low pumping power levels in planar nano-scaled structures.

310GHz gain-bandwidth product Ge/Si avalanche photodetector by selective epitaxial growth

Abstract: We report a normal incident Ge/Si avalanche photodiode by selective epitaxial growth. By eliminating germanium impact-ionization at high gain, high responsivity of 12A/W and large gain-bandwidth product of 310GHz have been achieved at 1550nm.