SIMULATION STUDY OF InP-BASED UNI-TRAVELING CARRIER PHOTODIODE
With the advent of optical amplifiers, the photodetector requirement for optical signal detection has changed. The high gain electrical amplifier used after the photodiode, can be replaced with an optical amplifier with a high power photodiode. The viability of this replacement can be judged on the basis of the system bandwidth, quantum efficiency and high power output as the figures of merit. We report the results of a simulation study of the structure and operation of an InGaAs/InP Uni-traveling carrier photodiode (UTC-PD) reported to have a high speed and high saturation output with a 3-dB bandwidth of ~ 80 GHz, operating at an optical fiber communication wavelength of 1.55 micron. The key feature of this device structure is the separation of the heavily doped p-type In0.53Ga0.47As absorption layer as the detection layer and a wide gap InP collection layer as the collection region. The photogenerated holes have little effect on the operation speed of the photodiode because the dielectric relaxation time of these carriers is negligible while the electrons are the only active carriers, which diffuse towards the collector layer and drift across the layer at a high speed. The use of In1-xGaxAsyP1-y layer at the top of the absorption layer is to act as a diffusion block while that at the bottom of the absorption layer is to reduce the effect of InGaAs/InP conduction band discontinuity. The device is modeled using Silvaco Internationals numerical device simulator ATLAS using researched parameters and the DC, AC and transient performance of the device are reported. We also report the development of a simple analytical model of the device to understand the underlying device physics. The optimization of the UTC-PDs device structure is investigated and the results compared with the structure reported by Ishibashi et al.
School:University of Cincinnati
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:photodiode indium phosphide inoium gallium arsenide
Date of Publication:01/01/2003