LiNbO3上的中红外热阻石墨烯探测器
Mid-infrared pyro-resistive graphene detector on LiNbO3
摘要：
中红外（mid-IR）光检测由于其多种应用（包括振动光谱和热成像）而近来变得越来越重要。我们提出并展示了一种新型的热电阻光电检测平台，该平台结合了铁电衬底（z切LiNbO 3晶体）和石墨烯层转移到其表面上的电连接。在LiNbO 3衬底中的强光吸收和随后的温度升高时，通过热释电效应，在晶体表面形成偏振（束缚）电荷。这些导致掺杂到石墨烯中，这反过来又改变了其载流子密度和电导率。以这种方式，通过监测石墨烯电阻，可以测量入射光功率。.在6 ~ 10 μ m波长范围内的探测率约为10^5 cm sqrt（Hz）/W。我们解释了热阻光电探测的基本物理机制，并提出了一个精确再现实验结果的模型。我们还表明，高达两个数量级的更大的探测率可以通过优化的几何形状和在真空中操作，从而打开了一个新的类的中红外光电探测器，可以挑战经典的碲镉汞设备，特别是在实际应用中，冷却是要避免和低成本是至关重要的。
英文摘要：
Mid-infrared (mid-IR) photo-detection has been recently growing in importance because of its multiple applications, including vibrational spectroscopy and thermal imaging. We propose and demonstrate a novel pyro-resistive photo-detection platform that combines a ferroelectric substrate (a z-cut LiNbO3 crystal) and a graphene layer transferred on top of its surface with electrical connections. Upon strong light absorption in the LiNbO3 substrate and the subsequent temperature increase, via the pyroelectric effect, polarization (bound) charges form at the crystal surface. These causes doping into graphene which in turn changes its carrier density and conductivity. In this way, by monitoring the graphene electrical resistance one can measure the incident optical power. . Detectivities of about 10^5 cm sqrt(Hz)/W in the 6 to 10 microns wavelength region are demonstrated.We explain the underlying physical mechanism of the pyro-resistive photo-detection and propose a model that reproduces accurately the experimental results. We also show that up to two orders of magnitude larger detectivity can be achieved by optimising the geometry and operating in vacuum, thus opening the path to a new class of mid-IR photo-detectors that can challenge classical HgCdTe devices, especially in real applications where cooling is to be avoided and low cost is crucial.
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