Silicon Meets Graphene for a New Family of Near-Infrared Schottky Photodetectors

Abstract

In recent years, graphene has attracted much interest due to its unique properties of flexibility, strong light-matter interaction, high carrier mobility and broadband absorption. In addition, graphene can be deposited on many substrates including silicon with which is able to form Schottky junctions, opening the path to the realization of near-infrared photodetectors based on the internal photoemission effect where graphene plays the role of the metal. In this work, we review the very recent progress of the near-infrared photodetectors based on Schottky junctions involving graphene. This new family of device promises to overcome the limitations of the Schottky photodetectors based on metals showing the potentialities to compare favorably with germanium photodetectors currently employed in silicon photonics.

Visible to Mid-Infrared Photodetection Based on Flexible 3D Graphene/Organic Hybrid Photodetector with Ultrahigh Responsivity at Ambient Conditions

“…Near-infrared (NIR) and mid-infrared (MIR) light detection play vital roles in thermal imaging, biometrics, and military surveillance. Particularly, MIR detection covers the molecular vibrational regions, which can be employed in gas detection, liquid inspection, and biological tissue identification. − However, the current NIR and MIR photodetectors are generally made of narrow-bandgap inorganic materials such as Si, GaInAs, HgCdTe alloys, and quantum-well and quantum-dot structure − that suffer from rigid mechanical property, fabrication technology limitation, and working environments, severely limiting their applications, especially in flexible and wearable electronics. − Organic semiconductors have attracted tremendous attention owning to intrinsic flexible properties, solution processability, rather tunable bandgap, large-scale roll to roll production, and compatibility with flexible substrate, showing promising applications in next-generation flexible photodetectors for visible light detection. − However, they generally suffer from large bandgap, weak absorption, and poor charge generation in NIR and MIR regions, resulting in poor performance long-wavelength detection. The gapless two-dimension (2D) single-layer graphene exhibits potential NIR and MIR detection at room temperature because of its unique electronic structure, broad spectra absorption, easy fabrication, and flexibility, − making it attractive for broadband and flexible photodetectors. − In the past few years, long-wavelength photodetector based on graphene (λ = 2 μm), , HgTe/graphene (λ = 1.55 μm), PbS/graphene (λ = 1.4 μm), etc., have been developed by fabricating photoconductor and phototransistors.…”

A Broadband Photoelectronic Detector in a Silicon Nanopillar Array with High Detectivity Enhanced by a Monolayer Graphene

“…First, the illumination light is absorbed by the graphene. Although the absorption ratio by the graphene is around 2.3%, − the photoexcited hot electrons may undergo a carrier soft-multiplication , and subsequently cross the Schottky barrier in the graphene/n-type Si interface through internal photoemission, acting as a photocurrent. − Second, in the depletion region of the Schottky junction near the graphene/n-type Si interface, most of the photoexcited carriers (electron–hole pairs) are generated in the thin n-type Si layer. The photoexcited carriers are then separated, the majority carriers (electrons) are transferred into the n-type Si layer, and the minority carriers (holes) are injected into the graphene layer under the built-in field, leading to another part of the photocurrent.…”

Integrated Photodetectors Based on Group IV and Colloidal Semiconductors: Current State of Affairs

“…An interesting and complete review of PDs based on graphene/semiconductor hybrid heterostructures, comprising device physics, design, performance, and process technologies for the optimization of PDs was recently published by Shin and Choi [ 109 ]. Considering that generally an all-Si approach is desired to take advantage by the existing CMOS technologies, a detailed review on the emerging field of the NIR internal photoemission effect-based graphene/Si PDs is presented by Casalino [ 110 ].…”