A Polysilicon Avalanche Light-emitting Devices For On-chip Optical Biosensing

Biosensing technology is an emerging interdisciplinary research hotspot.A variety of biosensors have been designed and fabricated to rapidly detect pathogens,proteins,and other specific analytes by combining specific biometric components with transducers for signal processing detection tool.Photoelectric biosensors include three main components:light source,optical waveguide,and photodetector.In order to reduce detection costs and meet the requirements of high sensitivity and large-scale manufacturing,the main components are made of silicon materials or silicon-based materials.Biosensors are gradually attracting the attention of researchers.All-silicon photoelectric biosensing needs to manufacture the main three components from silicon or silicon-based materials and realize the sensing function.Combined with the existing relatively mature microelectronics technology,it has gradually become the focus of research and development personnel in various countries in recent years.With the continuous deepening of requirements for miniaturization and low cost,there is an urgent need to break through the integration of silicon light sources,silicon waveguides and silicon photodetectors.At present,the waveguide technology and silicon photodetector technology are relatively mature,and the research and development of high-efficiency silicon light sources has become the key to this technology.In view of the development of on-chip sensors,this thesis mainly studies and discusses the design optimization of a bipolar-like polysilicon avalanche light-emitting device.The test is used to analyze the possibility of on-chip application of avalanche light-emitting devices made of polysilicon materials.The device uses polysilicon as a light-emitting material,and can be designed and fabricated by using a standard CMOS process.By applying a reverse-bias voltage,electroluminescence is triggered at the reverse-biased junction.For testing,gold wires were used to lead the electrodes out and a dual in-line ceramic package was used,and a corresponding test circuit board was designed.We selected 5 devices with different widths of P-type doped regions for testing.Among them,the width of the base region was the largest device had a breakdown voltage of 7.2 V.The test results using a spectrometer show that the luminescence spectrum of the bipolar-like polysilicon avalanche light-emitting device is continuous,with obvious peak distributions at 680 nm and 760 nm wavelengths,and the approximate linear relationship between the luminous intensity and the current and voltage is confirmed.Under the condition of applying the same reverse bias voltage,the device with shorter base width has stronger electroluminescence intensity.In addition,a light-emitting device with a shorter base width can achieve higher luminous efficiency and relatively lower electrical power consumption.Due to the difference in the refractive index of Si/SiO₂,the optical radiation emitted from the device was observed to have dispersion characteristics at 5 degrees,15 degrees,30 degrees,45degrees and 60 degrees through a microscope,and when the angle was greater than 30degrees,the dispersion phenomenon would be more and more obvious.Based on the tested electrical and optical properties,an optical waveguide-based biosensing structure and a microfluidic channel biosensing structure were designed.