NUMERICAL SIMULATION OF GaAsSb/InP UNI-TRAVELING CARRIER PHOTODIODE

 
 
 
 

NUMERICAL SIMULATION OF GaAsSb/InP UNI-TRAVELING CARRIER PHOTODIODE

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Title: NUMERICAL SIMULATION OF GaAsSb/InP UNI-TRAVELING CARRIER PHOTODIODE
Author: SHRESTHA, YUBA R
Description: The advent of the optical fiber amplifier has extended the distance between two repeaters and changed the role of the photodetector in an optical receiver in an optical fiber communication system. This new development enables amplification of the signal in its optical form before detection so that the photodetector must now be capable of responding to the high frequency, high power input optical signal without distortion, thereby eliminating the post detection amplification in electrical domain. The conventional p-i-n photodetector, which uses a depleted intrinsic layer as the light absorbing layer suffers from space charge buildup at high input optical power due to the slower movement of the photogenerated holes and so cannot respond adequately. A new type of photodetector, the Uni-Traveling Carrier Photodiode (UTC-PD), overcomes the limitations of the PIN by using a heavily doped p-type photoabsorption layer and a fully depleted, intrinsic wide bandgap collection layer. In the UTC-PD, photogenerated holes are the majority carrier in the absorption layer so their speed of response is determined by the dielectric relaxation time, which is normally very small (~ picoseconds). Therefore, only electrons are active carriers in an UTC-PD and as they move faster than the holes, the device response is much faster. In this thesis study, we have simulated the performance of a novel GaAsSb/InP UTC-PD as a possible replacement for the previously demonstrated InP/InGaAs UTC-PD. The study was performed using a commercial numerical device simulator ATLAS from Silvaco International for a 1.55 µm wavelength. This novel UTC-PD utilizes a p+ GaAsSb with a bandgap energy of 0.72 eV as the absorption layer and a Gaussian doping profile, n- InP as the depleted collection layer, n+ InP as the n+ contact, p+ InAlAs as the main electron blocking layer, p+ InGaAs as the p+ contact and a thin layer of p+ InGaAlAs as a spacer layer between GaAsSb absorption layer and InAlAs electron blocking layer. The simulation results for the device with a 0.2 micron thick absorption layer shows a 3 dB frequency of 41 GHz, responsivity of 0.35 A/W and quantum efficiency of 0.27. Also investigated were variations in the device’s structure and their effects on device performance.
Permanent Link: http://rave.ohiolink.edu/etdc/view?acc_num=ucin1115823666
http://hdl.handle.net/2374.OX/12104
Date: 2005

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