Characterization of Carbon Nanotube Based Infrared Photodetector Using Digital Microscopy

The state-of-the-art infrared camera suffers from the trade-off between sensitivity and cost. The bolometer infrared sensors are low resolution and slow speed while the quantum photodetectors are bulky and expensive. In this paper, the novel low dimensional material Carbon Nanotube (CNT) based non-cryogenic photodetector is proposed to detect infrared (IR) irradiance. The photoconductance and photovoltaic effect need to be distinguished to fully understand and improve nano IR detector performance. The robust test bench using digital microscope and precise five axis substage is used to measure detector photoresponse. The relative position between nanoscale sensor and IR beam is localized by mapping the photocurrent on laser spot. The distance between photodetector and infrared laser lens is leveraged by digital microscope. The experimental results show photovoltaic quantum effect dominates CNT-Metal Schottky based IR detector and the photoresponse is dependent on contact size and metal materials. The photoresponsivity can reach to 16.8 μA/mW at 808 nm wavelength. The proposed method will be applicable for 1D/2D nanoscale material based photodiode characterization.