Study On Structure Design And Performance Of Novel Filterless Wavelength Sensors

Wavelength sensors are employed in security monitoring,biomimetic eyes,autonomous vehicles,and spectrometers as a result of superior performance in light wavelengths distinguishing.Currently,commercial wavelength sensors are bulky due to the presence of optical-assisted components.The advent of filterless wavelength sensors has resulted in a significant size reduction,while this type of wavelength sensor has the disadvantage of complex device structure,low resolution and narrow detection range.Therefore,to solve the above problems,based on the absorption coefficient of the silicon-dependent incident light wavelength,a series of new filterless high-resolution wavelength sensors have been designed and investigated to distinguish wavelengths and enable color recognition.The working principle of the wavelength sensors also investigate.Furthermore,the well-performing MAPb I3 wavelength sensor is also successfully fabrication to drive the research progress of perovskite in wavelength recognition and full-color image sensing.The main results are summarized as follows:(1)A wavelength sensor consisting of two Pd Se2/20 μm Si/Pd Se2 heterojunction photodetectors stacked vertically is proposed for the first time,and a method for distinguishing wavelengths by photocurrent ratios is given.Due to the relatively thin thickness of the Si and the wavelength-dependent absorption coefficient,the two Pd Se2/20 μm Si/Pd Se2 photodetectors according to theoretical simulation display sharp contrast in distribution of photo-absorption rate.As a result,the photocurrents of both photodetectors evolve in completely different ways with increasing wavelength,leading to a monotonic decrease in photocurrent ratio from 6800 to 22 when the wavelength gradually increases from 265 nm to 1050 nm.The corresponding relationship between both photocurrent ratio and wavelength can be easily described by a monotonic function which can help to precisely determine the wavelength(265 nm to 1050 nm)within 5 nm resolution,with an average relative error less than ±1.6%.It is also revealed that by slightly revising the monotonic function,the wavelength in other different temperatures can also be estimated.(2)A wavelength sensor with a simple-structure that can not only quantitatively distinguish the wavelength in the range of ultraviolet to near-infrared light but also achieve color recognition is presented for the first time.The wavelength sensor is fabricated by depositing two parallel Au electrodes on the two sides of a 200 μm Si wafer.It is found that the as-formed two photodetectors display completely different optical properties.And then,the relationship between the photocurrent ratio of two photodetectors and incident wavelength can be described as a numerical function,through which the wavelength from 265 to 1050 nm can be precisely calculated.The unique operation mechanism of the Si wavelength sensor is unveiled by Technology Computer Aided Design(TCAD)simulation.Remarkably,the wavelength sensor easily distinguishes the light with a wavelength difference of 1 nm,which is much better than previously reported devices based on the vertically stacked structures and charge collection narrowing mechanism.(3)In this study,a simple-structured wavelength sensor assembled by depositing two back-to-back Au/MAPb I3/Au photodetectors on a MAPb I3 single crystal can quantitatively distinguish wavelengths.Further device analysis reveals that two photodetectors possess completely different optoelectronic properties.Consequently,according to the relationship between the photocurrent ratio of two photodetectors and incident wavelength,the wavelength sensors can accurately discriminate the incident light wavelengths ranging from 265 to 860 nm within a resolution of 1.5 nm.Impressively,these values are among the optimum their kind previously reported,and allow demonstration of full-color imaging.Additionally,TCAD simulations reveal that the mechanism in wavelength distinguishing is attributed to the wavelength-dependent photon generation rate in MAPb I3 single crystals.The well-performing MAPb I3 wavelength sensor is also prospective to drive the research progress of perovskite in wavelength recognition and full-color image sensing.