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TCAD Simulations of Uni-Traveling-Carrier Photodiodes

Syed Rahman
Göteborg : Chalmers tekniska högskola, 2006.
[Examensarbete på avancerad nivå]

This thesis presents numerical simulations and optimization of the Uni-Traveling Carrier Photodiodes (UTC-PD) using a commercial software (ISE-TCAD) along with some comparisons with published results. Physical properties of the UTC-PD have been investigated at different optical injection levels. Modulation of the energy band profile due to the space charge effect has been observed at high injection level. An electron velocity overshoot of 4×10P7Pcm/s at the heterointerface has been found to effectively delay the onset of space charge effects. Other key interest parameters are the responsivity and bandwidth. A maximum responsivity of 0.31 A/W and a small signal 3-dB bandwidth of 70 GHz was obtained for a 220 nm thick InGaAs absorption layer. The relationship between bandwidth and absorption layer thickness was also studied and it followed the expected trend. It has been verified with different load resistances that the bandwidth of a large area device is RC-limited. At high optical injection, a 17% increase in bandwidth was observed as a result of self induced electric field associated with carrier injection. It has been shown that the photoresponse of the UTC-PD could be improved by incorporating a graded doping profile in the absorption layer. For a 220 nm absorption layer thickness, a 15% increase in 3-dB bandwidth has been achieved with a graded doping profile.

Nyckelord: UTC-PD, TCAD, Photodiode

Publikationen registrerades 2007-03-08. Den ändrades senast 2013-04-04

CPL ID: 23001

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