自栅控量子点场效应单光子探测器及光电流增益相关机理研究

Single-photon detector is the very important device utilized in the field of time-correlated photon counting and quantum information, with increasingly urgent demand. The project carries out research on a near-infrared single-photon detector based on quantum dot field effect transistor structure, in which a single photo-carrier in quantum dot is controlling the on-off state of the low-noise self-gated channel. The channel is a kind of asymmetric source and drain structure, which can realize the self on-off control with more than exponential pattern. This device is supposed to achieve higher single-photon detection rate，low dark count, low working voltage, and at near room temperature working function at the same time, devices with all these properties will improve single-photon detection performance. The project research includes: The structural optimization of the self-gated field-effect structure and the control of the critical switching state; the photo-carrier capture and recombination dynamics in self-organized quantum dots; Analyses and suppression of the noise form two-dimensional electron gas channel, so as to improve the signal to noise ratio; Establishing the overall device mathematical model of the photoelectric gain and clarifying the high optical gain mechanism of the quantum dot gated field-effect devices; Fabrication examination and device certification. 5~10 Papers on high-performance single-photon detector are expect to be published and the research results will promote the development of single-photon detection.

单光子是弱光信号的探测极限，在时间相关的光子计数和量子信息等领域有越来越广泛和迫切的需求。本课题研究一种新型的自栅控沟道的量子点场效应单光子探测器，利用非对称沟道的源漏电势差对表面空间电荷区的调节使沟道电流处于开关临界状态，以量子点中的光生电荷对开关状态进行调控，以期获得同时具有低电压、低暗记数、高探测效率、近室温工作等优越特性的单光子探测器件。研究内容主要包括，自栅控沟道场效应结构的超指数开关临界状态控制与结构优化;自组织量子点中光生载流子的俘获和复合动力学特性研究,高俘获效率和寿命可控量子点的设计;二维电子气沟道的噪声来源分析和抑制途径研究，提高器件信噪比;建立整体器件的光电增益数学模型，阐明自栅控量子点场效应器件的高光电增益机制；制备和测试方法研究和最终器件验证。预期发表文章5～10篇高性能单光子探测器件相关文章，研究结果将推进量子点场效应单光子探测器的实用化发展。

单光子探测技术在量子信息、生物医学测量等领域具有十分广泛而重要的应用。在此需求背景下，本项目对量子点栅控场效应光电探测器进行详尽分析，并在此三极器件基础之上研究了新型的量子点自栅控场效应光电探测器，自栅控的特性使得器件可以工作在源漏两极的场效应器件工作模式，在器件工作的开关临界状态达到最灵敏的光子探测。具体研究包括探测原理、探测器结构和探测性能：1) 量子点栅控场效应探测器工作原理2)量子点自栅控场效应单光子探测器光增益的分析3) 自栅控量子点场效应光电探测器的结构设计与仿真4) 量子点自栅控场效应探测器的制备5）器件的测试。通过上述的研究，本项目明晰了自栅控场效应探测器的工作原理，并且通过模拟优化了器件的结构，最终研究开发了一套此种特殊器件制备工艺，得到了光电探测的测试结果。器件结果标明：50K温度下，入射光功率4.3×10-14W时所引起的电流变化约为105nA，由于光子频率为80MHz，入射光已经是以单个光子脉冲的形式入射到器件上。由于器件电流增益达到108,但器件的响应时间是秒量级，器件无法响应高速到达的光子序列。因此研究提高具有二阶光电导效应的量子点栅控场效应光电探测器的响应时间，是下一个新的研究课题，继续研究提高响应速度的方法，有望达到高速的单光子探测。

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