Design And Fabrication Of Colloidal Quantum Dot Metasurface Photoelectric Detector

At present,the development of infrared detectors is rapid,and third-generation infrared detectors have a gaze-forming system with large-area array and two-color detection functions.From the physical mechanism,the infrared radiation emitted by the detection target is essentially an electromagnetic wave,which has information of multiple dimensions such as intensity,wavelength and polarization.The traditional detector is essentially an energy distribution detector.It only has the ability to perceive the intensity information of electromagnetic radiation at the pixel level,and has no ability to perceive wavelength information and polarization capability information.Therefore,conventional detectors rely on discrete components such as filters and polarizers.This paper proposes the use of pixel-level integrated optical metasurface design and preparation of colloidal quantum dot metasurface photoconductive detectors.The detector has the functions of wavelength selection and polarization detection at the pixel level,improving the detection dimension and efficiency in the short-wave infrared range(1-3?m).In this paper,based on the local surface plasmon resonance effect and guided mode resonance principle,two kinds of colloidal quantum dot metasurface photodetectors are proposed and designed.The finite element algorithm is used to simulate the geometric dimension in COMSOL software.The colloidal quantum dot ridge structure metasurface photodetector: silicon substrate thickness 200 nm,colloidal quantum dot layer thickness 100 nm,silicon monolayer thickness 100 nm,silicon bump thickness 100 nm,period width 900 nm,duty ratio 0.5.At the optical communication window 1550 nm,the TM wave has the peak absorption rate of 99.6%,with a line width of 37 nm,and the TE wave absorption rate is only 2.4%.By adjusting the period and other parameters,the TM wave absorption peak position can be moved,and other optical characteristics are almost unchanged.The colloidal quantum dot interdigital electrode metasurface photodetector adjusts the parameters in a similar manner.The TM wave has a maximum absorption rate of 99.5% at 1550 nm,an absorption peak with a line width of 41 nm,and the TE wave of only 12.4%.Samples of the two detectors were prepared by simulation of the parameters obtained.Set up the test platform and measure the optical measurement of the sample.It can be concluded that the optical absorption peak wavelength of the colloidal quantum dot ridge structure metasurface samples are consistent with the simulation,which is 1550 nm,and have wavelength tunable and polarization characteristics.Due to the process size error and the limitation of measuring the incident angle,the actual measured absorption peak is broadened and there is room for optimization.Samples of two colloidal quantum dot metasurface photodetectors were prepared by the electron beam lithography process and FIB etching process.Detecting by self-built optical measurement system,the optical measurement results of the sample of the colloidal quantum dot ridge structure metasurface photodetector are worse than the simulation results,but the absorption of the specific wavelength of 1550 nm can still be achieved,and the highest absorption rate is about 85%,the measurement line width is 113 nm.The reason for the measurement optical performance deterioration is mainly due to the inevitable 25 degree inclination of the incident light swatch of the measurement system,followed by the process and measurement error.Colloidal quantum dot metasurface photodetectors can be applied in the field of optical communication,multi-color imaging,polarization imaging,and hyperspectral imaging.