Study Of Uni-traveling-carrier Photodetector

An analog photodetector is one of the important components of photoelectric detection system,which plays a critical role in the field of microwave photonics.It is a kind of photoelectric device converting a light signal into an electric signal.With the rapid development of science and technology,there are more and more requirements for high performance photodetectors which are required to have not only a high-speed,but also high power output.Because of the special structure of the single carrier photodetector,only electrons are active carriers,which have high mobility and high saturation output.The main work is focused on Uni-Traveling-Carrier Photodetector(UTC-PD).The research results are as follows:1.A vertical-illuminated UTC-PD is designed,and a two-dimensional model is established.Through the device simulation software,ATLAS,the microscopic characteristics of the device are analysed in detail,such as energy band structure,the distribution of carrier concentration,the distribution of electric field,and the distribution of current density.Through the simulation analysis on the DC characteristics of the device and the AC small signal characteristics,the characteristic parameters of the device is given.The 3dB bandwidth is about 10 GHz,the saturation current is 163 mA,and the responsivity is 0.544 A/W.2.The uni-traveling-carrier waveguide photodetector is fabricated.The design of the lithographic plate has been completed,including the designs and fabrications of photoetch pattern and the registration mark.The machining error is 0.2um.Before the formal substrate processing,the debugging in lithography on the InP substrate were first completed,including photolithography and etching process.The analysis of the testing result has been completed.Then,the semiconductor process on formal substrate has been completed,including Hexamethyl-disilazane(HMDS)pretreatment,lithography,etching,electrode fabrication the basement,thinning and cutting chip.3.After the fabrication of the waveguide photodetector,the test platform has been built,purchased related equipments,and tested the performance parameters of optical waveguide detector.The test results were compared with the theoretical data.The faultiness of the original structure parameter was found,and the original optical waveguide photodetector has been improved through changing the material thickness and doping concentration.The structure of the waveguide photodetector has been optimized.At the same time,the problems of the waveguide photodetector in the manufacturing process,such as the alignment between the up ridge waveguide with the down ridge waveguide,the roughness of waveguide side walls,were analyzed.These data provide theoretical and practical basis for the next time fabrication of the waveguide photodetector,to reduce the influence on the performance of the devices.4.According to the structural parameters of the optimization waveguide photodetector,a two-dimensional model is established.The microscopic properties of the device was analyzed by using device simulation software ATLAS.At the same time,the characteristic parameters of the device is got through the DC and AC small signal analysis.