Murata Takahiko, Asahi Shigeo, Sanguinetti Stefano, Kita Takashi
Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan.
L-NESS and Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, 20125, Milan, Italy.
Sci Rep. 2020 Jul 15;10(1):11628. doi: 10.1038/s41598-020-68461-w.
Mid-infrared sensors detect infrared radiation emitted from objects, and are actually widely used for monitoring gases and moisture as well as for imaging objects at or above room temperature. Infrared photodetectors offer fast detection, but many devices cannot provide high responsivity at room temperature. Here we demonstrate infrared sensing with high responsivity at room temperature. The central part of our device is an AlGaAs/GaAs heterostructure containing InAs quantum-dot (QD) layer with a 10-nm-thick GaAs spacer. In this device, the electrons that have been accumulated at the heterointerface are transferred to the conduction band of the AlGaAs barrier by absorbing infrared photons and the following drift due to the electric field at the interface. These intraband transitions at the heterointerface are sensitized by the QDs, suggesting that the presence of the QDs increases the strength of the intraband transition near the heterointerface. The room-temperature responsivity spectrum exhibits several peaks in the mid-infrared wavelength region, corresponding to transitions from the InAs QD and wetting layer states as well as the transition from the quantized state of the triangular potential well at the two-dimensional heterointerface. We find that the responsivity is almost independent of the temperature and the maximum value at 295 K is 0.8 A/W at ~ 6.6 µm for a bias of 1 V, where the specific detectivity is [Formula: see text] cmHz/W.
中红外传感器可检测物体发出的红外辐射，实际上广泛应用于气体和湿度监测以及对室温及室温以上物体进行成像。红外光电探测器具有快速检测能力，但许多器件在室温下无法提供高响应度。在此，我们展示了在室温下具有高响应度的红外传感。我们器件的核心部分是一个AlGaAs/GaAs异质结构，其中包含一个InAs量子点（QD）层和一个10纳米厚的GaAs间隔层。在该器件中，在异质界面处积累的电子通过吸收红外光子以及随后由于界面处电场引起的漂移而转移到AlGaAs势垒的导带中。异质界面处的这些带内跃迁由量子点敏化，这表明量子点的存在增加了异质界面附近带内跃迁的强度。室温响应度光谱在中红外波长区域呈现出几个峰值，对应于从InAs量子点和润湿层态的跃迁以及二维异质界面处三角形势阱的量子化态的跃迁。我们发现响应度几乎与温度无关，在295 K时，对于1 V的偏置电压，在约6.6 µm处的最大值为0.8 A/W，其中比探测率为[公式：见原文] cmHz/W。
