Research Of The Vertical Directional Coupling Photodiode

Photodetector plays an important role in the optical phased array radar system.Lacking of high-power and high-speed optical detector is the bottleneck that restricts thepractical application of the optical phased array radar. The traditional PIN photodiodeand the waveguide diode have many problems, In recent years, proposed a new type ofhigh-power high-speed photoelectric detection devices–VDCPD based on the DCPD,solved the phase shift problem and the microwave power problem of the optical phasedarray radar system.This dissertation focused on VDCPD with high current and high response speed.the main works are as follow:1. First, in the understanding of the basis of the research status, we propose a newVDCPD structrue. While the VDCPD meets a super mode matching condition that thecoupling length matches absorption lengths of the fundamental super mode and the firstsuper mode in the VDCPD, the photo current of the VDCPD is uniformly distributed toachieve high current.2. In the dissertation, BeamProp software are uesd to simulate to look for the valueof the structure that meets the matching condition and confirmed the value of itsstructure. Then the confirmed structure is tested to make sure it met the matchingcondition with Matlab program and the effective index method of waveguide optics.Especially, the way that adding an incident waveguide in the front of the VDCPD wascame up with to solve the problem which is the overburning of the incident end of theVDCPD, then reduce the fluctuations of the photocurrent.3. In the dissertation, the substrate of the VDCPD use UTC structure, a departmentof UTC membrane is designed, which used Silvaco software to analysis the carriertransport in the UTC structure, then it can contradiction of the the coordinationsaturation current and the response speed.4. The basic performance parameters of the VDCPD are optained, which3dBbandwidth of20GHz and transmit time of2.9e-11s. It could meet the high-powerhigh-speed operation theoretically. Theoretical design requires good process to support, at the last of this dissertation,we put forward some noteworthy subsequent problems, such as the growth of epitaxialwafers, mask design, corrosion processing, electrode production, etc. To produce a gooddetector which can strive all aspects of device characteristics, the theory is combinedwith the actual situation. Which to make up for the problems encountered in the actualprocessing through adjusting the structure parameters constantly.