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Light emitting diodes and photodetectors based on III-nitride and colloidal quantum dot materials.

机译：基于III族氮化物和胶体量子点材料的发光二极管和光电探测器。

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摘要

In this work, we first proposed the tandem architecture for solution-processed near infrared PbSe colloidal quantum dot (CQD)-based photodetectors to address the high dark current issue. The tandem architecture not only absorbs the virtue of tandem solar cell by means of efficient photon-to-current conversion, but also functions as the effective barrier that can block the leakage current. More than three orders of magnitude reduction in dark current has been observed, along with an elevated photocurrent. The low temperature current-voltage characteristics revealed that the tandem architecture posed a high energy barrier which effectively blocks the dark current. Our results suggest that tandem architecture can be employed to developing high-performance solution-processed photodetector.;The application of tandem photodetectors was further extended to sensors on flexible substrates where little study has been reported to date. Our results on flexible tandem photodetectors validate the high efficiency and detectivity of the tandem architecture. Two different bending states have been studied which revealed the small critical bend radii of ∼8mm and ∼3mm for tensile and compressive bending, respectively. The photodetector performance remains stable under mechanical stress which offers great potential of CQDs-based tandem photodetectors for flexible device applications.;Furthermore, we have demonstrated the chip level integration of flip-chip light emitting diode (LED) with current rectifying GaN Schottky barrier diodes constituting the Wheatstone bridge circuitry for alternating current (AC) driving. The flip-chip LED scheme offers better p-contact, high light extraction efficiency and fast heat dissipation. The reflectance and turn-on voltage were investigated under various p-contact annealing conditions. The flip-chip alternating current LEDs (ACLEDs) demonstrated more than ∼23% improvement in terms of energy conversion efficiency over top-emissive ACLEDs and offer the potential of using such device for high brightness, high power, high efficiency and high reliability solid state lighting applications.;Finally, built on our studies of LEDs and photodetectors, and of chip level integration of LEDs and GaN Schottky barrier diodes. we, for the first time, proposed the integration of visible LEDs and UV GaN photodetectors for bi-directional optical wireless communication (OWC) applications. The LEDs function as transmitters to emit visible light signal whereas the photodetectors as receivers to collect UV signals. The crosstalk can be neglected due to the superior visible-blind property of GaN UV photodetector. The experimental results demonstrated that the LEDs and photodetectors can work together efficiently which opens up a new avenue for using such device for bi-directional OWC applications.
机译：在这项工作中，我们首先提出了基于溶液处理的近红外PbSe胶体量子点（CQD）基光电探测器的串联架构，以解决高暗电流问题。串联结构不仅通过有效的光子到电流转换吸收了串联太阳能电池的优点，而且还充当了可以阻止泄漏电流的有效屏障。观察到暗电流减少了三个数量级以上，同时光电流也增加了。低温电流-电压特性表明，串联结构构成了高能垒，有效地阻挡了暗电流。我们的结果表明，串联体系结构可用于开发高性能溶液处理的光电探测器。串联光电探测器的应用进一步扩展到柔性基板上的传感器，迄今为止尚未有研究报道。我们在灵活的串联光电探测器上的研究结果验证了串联体系结构的高效率和探测能力。对两种不同的弯曲状态进行了研究，揭示了拉伸和压缩弯曲的临界弯曲半径分别约为8mm和3mm。在机械应力下，光电检测器性能保持稳定，这为柔性器件应用提供了基于CQD的串联光电检测器的巨大潜力。此外，我们已经证明了倒装芯片发光二极管（LED）与电流整流GaN肖特基势垒二极管的芯片级集成构成惠斯通电桥电路，用于交流电（AC）驱动。倒装芯片LED方案可提供更好的p接触，高光提取效率和快速散热。在各种p接触退火条件下研究了反射率和开启电压。倒装芯片交流电LED（ACLED）在能量转换效率方面比顶级LED ACLED改善了约23％以上，并提供了使用这种器件实现高亮度，高功率，高效率和高可靠性固态照明的潜力最后，以我们对LED和光电探测器的研究以及LED和GaN肖特基势垒二极管的芯片级集成为基础。我们首次提出了将可见光LED和UV GaN光电探测器集成在一起的双向光无线通信（OWC）应用。 LED用作发射可见光信号的发射器，而光电探测器则用作收集UV信号的接收器。由于GaN UV光电探测器具有出色的可见盲特性，因此可以忽略串扰。实验结果表明，LED和光电探测器可以有效地协同工作，这为将此类设备用于双向OWC应用开辟了一条新途径。

著录项

  • 作者

    Jiang, Zhenyu.;

  • 作者单位

    The Pennsylvania State University.;

  • 授予单位 The Pennsylvania State University.;
  • 学科 Electrical engineering.
  • 学位 Ph.D.
  • 年度 2014
  • 页码 150 p.
  • 总页数 150
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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