Narrow-band Near-infrared Photodetector Based On PbS Quantum Dots/silicon Micro-holes Array

Near-infrared(NIR)photodetectors show a great application in information technology and biomedicine fields.It is usually limited by many factors,such as high-cost filter and complex optical system design and integration.Silicon-based photodetectors are ideal for integrated optoelectronic devices due to their excellent compatibility with CMOS technology.Recently,the trapping silicon mirco-structures were used to construct Si-based NIR photodetectors due to the regular optical characteristics and easy fabrication by using the proven merits of well-developed silicon technologies.Lead sulfide quantum dots(Pb S QDs)show a potential application in NIR photodetectors due to the small band gap and large exciton Bohr radius.In this dissertation,the novel narrow-band NIR photodetector based on Pb S QDs/Si MHs was designed,constructed and then measured,which allows the combination of the Si MHs and unique Pb S QDs NIR properties.The main research contents and achievements of this dissertation are as follows.(1)Based on semiconductor optical absorption characteristics and device theory,a novel narrow-band NIR photodetector with Si MHs array back illuminated Schottky diode(SD)is proposed here.A three-dimensional SD photodetector model was built by using Silvaco TCAD,and the generation and collection characteristics of photogenerated carriers were studied.In order to optimize the near-infrared response performance of Schottky junction photodetector,the relationship between the near-infrared light field and the illumination angle of the device is explored by adjusting the silicon micropore light trapping structure.under our fabrication condition.(2)Based on the abovementional simulation and optimization design of the photodetectors,the Si MHs array was successfully fabricated by using the photolithography and inductively coupled plasma(ICP)etching method.The Si MHs/Gr SD was then constructed by wet-transferring the graphene as the bottom Schottky contact electrode.Subsequently,Pb S QDs/Si MHs/Gr photodetector was fabricated by controllable spin-coated Pb S QDs on the top of the Si MHs.The device shows an obvious NIR response with a peak near 1064 nm,a detectivity as high as 1.12í10¹²Jones and a responsivity approaching to 0.71 A/W,which are all more than two orders of magnitude higher than the Si MH_S/Gr SD and Si/Gr SD.(3)Based on the principle of PPG pulse monitoring,a pulse measurement system composed of Pb S QDs/Si MHs/Gr Schottky junction diode narrow band near infrared detector,1064 nm light emitting diode and amplifier is built.The heart rate detection system is comparable with commercial PPG,and has good anti-interference of ambient light.