Advisor: Krishna Saraswat
Date: Thursday, September 29, 2011Time: 9:30 AM
Location: Paul Allen Auditorium (Formerly CISX-101)
Title: Novel Phototransistors for Optical Interconnect
Abstract:
Interconnect is one of the major problems in high performance silicon chips in terms of latency, power and bandwidth. Optical interconnect has potential benefits to solve such problems. Because of very high carrier frequency, optical interconnect avoids the resistive loss physics of metal wires, thus high bandwidth is achievable. However, energy/bit is still high compared to conventional copper wire in short on-chip/off-chip interconnects. While lasers and optical modulators promise power requirement for on-chip optical interconnect lower than copper wire, receivers still consumes high power. To decrease receiver-end power consumption, receiver-less scheme had been proposed. To realize this, a device complimentary to photodetector is needed.
First part of this talk presents the first complimentary device to photodetector operates at 850nm laser with output current reduction with incident light. Experiment result successfully showed voltage shift of Id-Vg curve, which is signature of phototransistor operation, as big as 0.7V. It also presents the first wavelength tunable complimentary to photodetector operates at optical communication wavelength range. These phototransistors have potential to replace current optical receiver circuit and reduce power dissipation to meet power requirement.
Second part of this talk presents photodetector utilizes phototransistor concept. Responsivity higher than 700A/W is experimentally shown with 150nW of incident light in 850nm wavelength, which is higher than external quantum efficiency of 1000. In addition, small output capacitance of ~2fF/µm and high scalability are verified from simulation. With these characteristic, this phototransistor can replace conventional photodiode, and further decrease power dissipation of optical interconnect.
No comments:
Post a Comment