Presentation Information
[21p-A202-2]Ultrafast Optical-to-electrical Conversion Processes in Two-dimensional Materials
〇Katsumasa Yoshioka1 (1.NTT BRL)
Keywords:
optical-to-electrical conversion,graphene,photocurrent
With the anticipated exponential growth of data traffic, there is an imminent need for optical receivers that enable the conversion of optical signals into electrical signals while maintaining ultrahigh bandwidth and low power consumption. Graphene-based photodetectors utilizing the photothermoelectric (PTE) effect have gained significant attention due to their potential to outperform existing semiconductor devices. However, despite their promising potential, the demonstrated operational speed of these devices is limited to approximately 70 GHz, which falls far short of the theoretical expectation of 200 GHz. Despite the crucial role of optical-to-electrical conversion on the intrinsic timescale for the design of ultrafast graphene optoelectronic devices, achieving this capability and understanding its underlying mechanism have yet to be realized. Here, we showcase the ability to perform ultrafast electrical readout of PTE current in high-quality graphene. By employing on-chip terahertz spectroscopy and a zinc oxide gate structure that eliminates high-frequency capacitive coupling, we successfully overcome the limitations imposed by the bandwidth of readout electronics and the large RC time constant of the device.