Achieving higher photoabsorption than groupⅢ-Ⅴsemiconductors in ultrafast thin silicon photodetectors with integrated photon-trapping surface structures  

作　　者：Wayesh Qarony Ahmed S.Mayet Ekaterina Ponizovskaya Devine Soroush Ghandiparsi Cesar Bartolo-Perez Ahasan Ahamed Amita Rawat Hasina H.Mamtaz Toshishige Yamada Shih-Yuan Wang M.Saif Islama 

机构地区：[1]University of California,Davis,Department of Electrical and Computer Engineering,Davis,California,United States [2]W&WSens Devices,Inc.,Los Altos,California,United States [3]University of California,Baskin School of Engineering,Department of Electrical and Computer Engineering,Santa Cruz,California,United States

出　　处：《Advanced Photonics Nexus》2023年第5期33-43,共11页先进光子学通讯（英文）

基　　金：supported in part by the US Army’s Night Vision and Electronic Sensors Directorate(Grant No.W909MY-12-D-0008);NSF ECCS(Grant No.1428392)。

摘　　要：The photosensitivity of silicon is inherently very low in the visible electromagnetic spectrum,and it drops rapidly beyond 800 nm in near-infrared wavelengths.We have experimentally demonstrated a technique utilizing photon-trapping surface structures to show a prodigious improvement of photoabsorption in 1-μm-thin silicon,surpassing the inherent absorption efficiency of gallium arsenide for a broad spectrum.The photon-trapping structures allow the bending of normally incident light by almost 90 deg to transform into laterally propagating modes along the silicon plane.Consequently,the propagation length of light increases,contributing to more than one order of magnitude improvement in absorption efficiency in photodetectors.This high-absorption phenomenon is explained by finitedifference time-domain analysis,where we show an enhanced photon density of states while substantially reducing the optical group velocity of light compared to silicon without photon-trapping structures,leading to significantly enhanced light–matter interactions.Our simulations also predict an enhanced absorption efficiency of photodetectors designed using 30-and 100-nm silicon thin films that are compatible with CMOS electronics.Despite a very thin absorption layer,such photon-trapping structures can enable high-efficiency and high-speed photodetectors needed in ultrafast computer networks,data communication,and imaging systems,with the potential to revolutionize on-chip logic and optoelectronic integration.

关 键 词：PHOTOABSORPTION photon trapping group-velocity reduction PHOTODETECTORS silicon photonics 

分 类 号：O43[机械工程—光学工程]