The impact of atmospheric adsorbates on the spectral response and response speed of p-type graphene/n-type Silicon (p-Gr/n-Si) based Schottky barrier photodetectors are investigated. Wavelength resolved photocurrent and transient photocurrent spectroscopy measurements conducted under high-vacuum conditions revealed that the atmospheric adsorbates such as O2 and H2O stuck on graphene electrode lead to hole doping in graphene and therefore shift its Fermi level towards higher energy states below its Dirac point. Such a shift in graphene’s Fermi level due to adsorbates increases the zero-bias Schottky barrier height of the p-Gr/n-Si heterojunction from 0.71 to 0.78 eV. Adsorbate induced increment in the barrier height promotes the separation of photo-generated charge carriers at the depletion region and leads to an improvement in the maximum spectral response (e.g., from 0.39 to 0.46 AW−1) and response speed of the p-Gr/n-Si photodetector in the near-infrared region. The experimentally obtained results are expected to give an insight into the adsorbate related variations in the rectification and photo-response characters of the heterojunctions of graphene and other 2D materials with different semiconductors.

中文翻译：

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石墨烯/硅基肖特基势垒光电探测器中吸附物诱导的光谱响应增强

研究了大气吸附物对基于 p 型石墨烯/n 型硅 (p-Gr/n-Si) 的肖特基势垒光电探测器的光谱响应和响应速度的影响。在高真空条件下进行的波长分辨光电流和瞬态光电流光谱测量表明，吸附在石墨烯电极上的大气吸附物（如 O2 和 H2O）导致石墨烯中的空穴掺杂，因此将其费米能级转移到其狄拉克点以下的更高能态。由于吸附物引起的石墨烯费米能级的这种变化将 p-Gr/n-Si 异质结的零偏置肖特基势垒高度从 0.71 eV 增加到 0.78 eV。吸附物诱导的势垒高度增加促进了耗尽区光生载流子的分离，并导致最大光谱响应（例如，从 0.39 到 0.46 AW-1）和 p-Gr/近红外区域的 n-Si 光电探测器。实验获得的结果有望深入了解石墨烯和其他具有不同半导体的二维材料的异质结的整流和光响应特性的吸附物相关变化。