Light Trapping in Conformal Graphene/Silicon Nanoholes for High-Performance Photodetectors

Abstract

Hybrid graphene/silicon heterojunctions have been widely utilized in photodetectors because of their unique characteristics of high sensitivity, fast response, and CMOS compatibility. However, the photoresponse is restricted by the high reflectance of planar silicon (up to 50%). Herein, an improved graphene/Si detector with excellent light absorption performance is proposed and demonstrated by directly growing graphene on the surface of silicon nanoholes (SiNHs). It is shown that the combination of SiNHs with conformal graphene provides superior interfaces for efficient light trapping and transport of the photoexcited carriers. A high absorption of up to 90% was achieved, and the conformal graphene/SiNH-based photodetectors exhibited a higher photoresponsivity (2720 A/W) and faster response (∼6.2 μs), compared with the counterpart of the planar graphene/Si, for which the corresponding values are 850 A/W and 51.3 μs. These results showcase the vital role of the material morphology in optoelectronic conversion and pave the way to explore novel high-performance heterojunction photodetectors.

CVD Graphene on Textured Silicon: An Emerging Technologically Versatile Heterostructure for Energy and Detection Applications

“…Therefore, a remarkable advancement in this area has also taken place recently. [ 43,69,70,72,74,75,83 ] The performance of PDs including graphene/Si Schottky junction‐based PDs are mainly evaluated by responsivity, specific detectivity, noise equivalent power (NEP), normalized photo‐to‐dark current ratio, etc. Responsivity ( R ) is given by the following relation: where, I ph is the measured photo current, P in is the incident optical power density and A is the active area.…”

“…texturing of Si substrate to fabricate a high‐performance CVD‐graphene/Si based PD by Yang et al. [ 75 ] Direct growth of conformal graphene on SiNHs was achieved by using PECVD technique, and a conformal graphene/SiNHs heterojunction‐based photodetector was fabricated as shown in Figure 5. Figure a,b shows the schematic diagram and a SEM image of the fabricated conformal graphene/SiNHs PD, respectively, where PD was fabricated with the help of photolithography and lift‐off process.…”

Directly Synthesized Graphene-Based Photonics and Optoelectronics Devices

“…A recent report [108] describes the conformal growth of graphene on SiNH structure that worked as a photo-detecting device. In their process, silver-assisted etching method along with discretely distributed silver nanoparticles (AgNPs) was employed to form the SiNH structures as shown in Figure 5a.…”

“…A technique of explicit growth of graphene coatings on the surface of silicon nanoholes (SiNHs) through plasma enhanced chemical vapor deposition (PECVD) was projected to accomplish transfer-free conformal graphene/SiNH photo detectors for the first time [108]. The conformal graphene/SiNH structures were found to have an exceptional light absorption pursuance with absorptions risen up to 90%, and also consist high power absorption densities, that results in more photo carrier procreations per unit volume in the SiNHs than planar silicon.…”

Conformal Self-Assembly of Nanospheres for Light-Enhanced Airtightness Monitoring and Room-Temperature Gas Sensing

“…The utilization of conformal nanostructures formed on microarchitectures is of great significance for diverse applications, such as wetting tunability [ 1 , 2 ], flexible electronics [ 3 , 4 ], photodetectors [ 5 ], biomimetic photonics [ 6 ] and green energy [ 7 ]. Although micro/nanostructure fabrication via broad-range techniques of photolithography [ 8 ], laser etching [ 9 ], three-dimensional (3D) printing [ 10 ], thermal oxidation [ 11 ] and chemical deposition [ 12 ] has been highly developed, a method for validly constructing conformal nanostructures on complex microarchitectures remains elusive, especially for large-area fabrication of periodic nanostructures on convex and concave surfaces.…”