可撓式半透明網版印刷電極之金屬-半導體-金屬光感測器並應用奈米銀線提升靈敏度

Abstract

科技日益進步的時代，光感測器扮演著不可或缺的角色，無論在交通、醫療、生活上都與我們息息相關。且隨著穿戴式裝置需求量增加的同時，一簡單快速、可繞式裝置的需求，也將隨之增加。本研究藉由將單晶矽利用濕式蝕刻的方式得到30微米的厚度以達到可撓性，並製備高靈敏度且具奈米銀表面電漿共振效果的可撓式金屬－半導體－金屬光感測器。金屬－半導體－金屬光感測器有兩個具有整流效果的蕭特基接觸面，當照光後半導體空乏區，將會產生電子電洞對，進而產生光電流。為了提升本感測器之靈敏度，透過濕式蝕刻使得試片表面得到金字塔結構，驅使光的反射率降低了16.3%。電極我們採用網印製程，其一大優點為常溫常壓下操作，不需昂貴的真空設備，不僅對環境友好，也降低了成本。本研究選用直徑50奈米，長5微米的奈米銀線佈植於元件表面，由奈米銀線的表面電漿共振效果，提升元件的偵測極限及靈敏度,其靈敏度增加了491%。本元件可撓性佳，且可通過長時間的機械撓曲測試不影響其偵測能力.此可撓式光感測器具有高靈敏度、低偵測極限以及良好的機械性質、耐久性，未來將可應用在可攜式裝置上或輕量化低成本需求上。

Simple, rapid, flexible but robust devices used for chemical sensing and environmental pollution detection are in an urgent need since the rise of environmental consciousness. This study mainly focuses on fabrication methods of flexible photodetector. In detail, a highly sensitive ultrathin flexible metal-semiconductor-metal (MSM) photodetector has been developed on a 30-μm-thick single-crystalline silicon chip by a chemical etching process with a surface texturization design on the flexible device that enhances the light-trapping effect and minimizes reflectivity losses from the incident lights. The untextured chip has an average reflectivity of 37.06% at incident wavelengths from 350-850 nm, and the textured one demonstrates an average reflectivity of 20.76% that implicates a decrease in reflectivity of incident light by 16.3% after the texturization process. In this study, conductive electrodes are manufactured using screen-printing process that doesn’t demand expensive vacuum technology and can be applied to any surface shape; this is quite simple and cost-effective and the silver paste is used. Then the silver nanowires with 50 nm diameters and 5 μm lengths are assembled on the device surface; the resulting photocurrent has been enhanced by 491%. The development of this flexible MSM photodetector with high sensitivity and excellent mechanical flexibility demonstrates the applicability to the future sensor.