ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels, Barcelona, Spain.
Nat Nanotechnol. 2012 May 6;7(6):363-8. doi: 10.1038/nnano.2012.60.
Graphene is an attractive material for optoelectronics and photodetection applications because it offers a broad spectral bandwidth and fast response times. However, weak light absorption and the absence of a gain mechanism that can generate multiple charge carriers from one incident photon have limited the responsivity of graphene-based photodetectors to ∼10(-2) A W(-1). Here, we demonstrate a gain of ∼10(8) electrons per photon and a responsivity of ∼10(7) A W(-1) in a hybrid photodetector that consists of monolayer or bilayer graphene covered with a thin film of colloidal quantum dots. Strong and tunable light absorption in the quantum-dot layer creates electric charges that are transferred to the graphene, where they recirculate many times due to the high charge mobility of graphene and long trapped-charge lifetimes in the quantum-dot layer. The device, with a specific detectivity of 7 × 10(13) Jones, benefits from gate-tunable sensitivity and speed, spectral selectivity from the short-wavelength infrared to the visible, and compatibility with current circuit technologies.
石墨烯是一种有吸引力的光电和光电检测应用材料，因为它提供了宽的光谱带宽和快速的响应时间。然而，弱光吸收和缺乏增益机制，不能从一个入射光子产生多个载流子，限制了基于石墨烯的光电探测器的响应率到约 10(-2) A W(-1)。在这里，我们展示了一个混合光电探测器的增益约为 10(8)个电子每光子和响应率约为 10(7) A W(-1)，该探测器由单层或双层石墨烯覆盖有一层胶体量子点薄膜组成。量子点层中的强和可调谐光吸收产生的电荷被转移到石墨烯中，由于石墨烯的高电荷迁移率和量子点层中被捕获的电荷的长寿命，它们在石墨烯中多次循环。该器件的特定探测率为 7×10(13) 琼斯，受益于栅极可调灵敏度和速度、从短波长红外到可见光的光谱选择性以及与当前电路技术的兼容性。
