Design And Fabricate On High Speed InGaAs/InP Photodetector

Photodetector（PD）is a critical component for optically controlled optical fiber communication system.The band gap energy of In_0.53Ga_0.47As material is 0.75 eV,which is appropriate to PD for 1.31 and 1.55μm window of optical fiber communication.This dissertation work is focused on the development of high speed In_0.53Ga_0.47As photodetectors for optical communication applications in the range of 1.0¹.6μm.In this thesis,we studied the structure design and device process of InGaAs PD,and then the properties were studied and analyzed.The main contents were concluded as follows:（1）The optimization of zinc diffusion process.In this work,a semi-closed chamber was formed by a modified diffusion device,which included an annealing furnace,a computer system,a cooling water system,an aerating system and a vacuum pumping system.In order to inhibit the phosphorus loss from the InP cap layer,Zn₃P₂ particles were used as zinc source in the zinc diffusion process performed at 530 ^oC,580 ^oC and 650 ^oC,respectively.The zinc diffusion process provides further advantages,namely,（i）the operation is simple;（ii）heating and cooling speed is fast;（iii）a large area is easily diffused.The doping characteristics of Zn in InP were obtained by using the low temperature-dependent PL measurement.The optical process parameters were obtained and the performances of the planar InGaAs/InP PIN photodetectors were improved by modifying the diffusion system and investigating the primary mechanism of Zn diffusion.（2）The characteristics of InGaAs ohmic contact were investigated.The ohmic contact on InGaAs was fabricated and analyzed.The metal system were adopted with Ti/Pt/Au=75/75/250 nm for InGaAs.When the samples were annealed at 460 ^oC for 120 s and the doping concentration was 9.79×10¹⁸ cm^-3,good ohmic contacts were successfully obtained between the metal and p-InGaAs with a lowest resistivity of 4.323×10^-5??cm²and the metal with n-InGaAs of 6.980×10^-8??cm² at a doping concentration of 2.00×10¹⁹cm^-3.（3）The development of InGaAs/InP PIN and UTC photodetectors.Based on the optimization of characteristics of the photodetectors,the structures of reasonable InGaAs/InP PIN and UTC photodetectors were proposed.On the basis of the accomplishment of the key techniques that affect its performances,such as cleaning,lithography,peeling,electrode preparation and etching process conditions etc,the InGaAs/InP PIN and UTC photodetectors chips were fabricated by a recipe for the processing of photodetectors.（4）The main performance parameters of InGaAs/InP PIN and UTC photodetectors were tested.The performance parameters of the photodetector were measured using the corresponding test equipments and the performance results were analyzed.The 3-dB bandwidth of the InGaAs/InP PIN and UTC photodetectors were 11.64 GHz and 17.50 GHz,respectively.