Research On GaN-based Green Light-emitting And Sensing Integrated Chip For Visible Light Communication

The innovation of GaN epitaxial growth technology not only promotes the development of traditional lighting industry and display manufacturing technology,but also lays a solid foundation for the development of visible light communication.In recent years,high brightness light emitting diodes based on gallium nitride and high sensitivity photodetectors have been the research hotspots in visible light communication systems.Therefore,aiming at visible light communication,this paper explores the physical mechanism of green quantum well diode as both light-emitting device and receiving device.The device with the same quantum well structure can be prepared on a chip.At the same time,peripheral circuits and lens sets are designed to complete spatial optical communication verification.In this paper,the epitaxial layer of the chip is grown on 4-inch sapphire patterned substrate by MOCVD process;Photolithography defines the MQW region with a size of 230μm×230μm,the n-GaN layer of the device is exposed by ICP etching process;The region of each device is defined by the second lithography,and the n-GaN layer is etched to the substrate in order to separate devices.Depositing ITO layer on the p-GaN layer to stabilize the current diffusion during the operation of the device,and then evaporating the metal electrode;Si O₂passivation layer is deposited by PECVD process to protect the device;Finally,in order to improve the luminous efficacy of the device,the substrate is reduced and polished,and DBR film is evaporated on the back of the substrate.The test data show that the luminescence spectrum and detection spectrum of the chip overlap at 485～520nm,which can be used as a light source and photodetector for duplex communication.When the chip is used as the LED and the commercial APD is used as the receiver,the communication rate can reach 21Mbps and its-3d B bandwidth can reach 13MHz respectively.When the chip is used as the receiver,the duplex communication rate between homogeneous chips can reach 2.8kbps,it also has the communication ability when emitting light.Through light reverse communication experiment and light audio communication experiment,this paper proves that the chip has good detection ability for external signals.In the end,improve the utility of the chip in the visible light system by designing the pre-aggravating peripheral circuit and the lens group system.