Simulation And Process Of Evanescently Coupled InP/InGaAs Waveguide Detector

Photodetectors are an important part of the field of optical fiber communicat-ion.With the development of communication technology,the rapidly increasing amount od data transmission puts forward higher requirements for the high-speed performance of photodetectors.InGaAs,a ternary materical matched to the InP lattice,is an important materical for the two optical fiber communication windows of 1310 nm and 1550 nm.Compared with the surface illuminated and waveguide side illuminated,the evanescently coupled waveguide photodetector has been more and more widely studied because of its high coupling efficiency.In this paper,the key simulation and process of InP/InGaAs high-speed photodetector with integrated vertical taper spot size converter is studied.The main contents of this article include:1.The theoretical knowledge of photodetector principles,types and other theories is introduced.Have a deeper understanding of various types of photo-detector.The theoretical knowledge of spot size converter was studied.2.The simulation and experimental preparation of vertical taper spot size converter(SSC)were carried out.In order to improve the coupling efficiency of fiber and waveguide,this paper studies a photodetector with integrated vertical taper SSC.Firstly,the dimensions of the SSC were determined.Contact lithography is used,multiple overlays to form a step shape on the photoresist.The thermal reflow makes steps form a slop.The insertion loss and 1 dB alignment tolerance after integrated SSC were experimentally determined.Compared to without SSC,the insertion loss is reduced from 1.8 dB to 1.0 dB.The horizontal alignment tolerance is increased from±0.4 μm to ±2.5 μm.The vertical alignment tolerance is increased from ±0.5 μm to ±3.0μm.3.Both dry and wet etching were used for the preparation of P/N mesa.The simulation determined that the active region area was 5 μm× 20 μm.During wet etching,both InGaAs and InGaAsP are etched.Therefore,the effects of insufficient etching depth and over-etching on photodetector bandwidth and responsivity are simulated.The result show that the device can tolerate some degree of over-etching.In the experiment,dry and H3PO4 wet etching solution was used.The P/N mesa that meets the requirements was obtained.4.Ohmic contact process optimization.The specific contact resistivity of the electrode under various annealing condition was measured by the TLM method.The smallest specific contact resistivity was obtained under anneal-ing conditions of 420℃,30 s.5.After all process were completed,the photodetector was measured for 3 dB bandwidth and responsivity.The measured 3 dB bandwidth is 26.2 GHz and the responsivity is 0.8 A/W.The 3 dB bandwidth differs greatly from the simulation,and the reasons for this are analyzed.