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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Piezo-phototronics: from experiments to theory

Liu, Ying 21 September 2015 (has links)
The piezo-phototronics effect is the three way coupling of semiconductor properties, photonics and piezoelectricity in the same material. Research on piezo-phototronics effect has illustrated its application on various Zinc Oxide (ZnO) nanowire based devices, yet a systematical study with comprehensive theoretical model is still missing. Here we have designed experiments on wider variety of materials to investigate the mechanism of the piezo-phototronics effect, and then built up a theoretical model for more thorough understanding. Experimental results are shown for Cadmium Sulfide (CdS) photodetectors for visible light detection, inorganic/organic hybrid Light Emitting Diodes (LEDs) and LED arrays, and it is demonstrated that strain can significantly tune the performance of these optoelectronic devices. Theoretical methodologies are proposed for Metal-Semiconductor-Metal (MSM) structure and p-n junctions, including analytical solutions and Finite Element Method (FEM) simulations. For Schottky contacts in photodetectors, barrier height change is determined as the main reason for the effect, and an exponential relationship between applied external strain and the device current is discovered, and is qualitatively confirmed from experimental results. For p-n junctions in LEDs, change in size of depletion region under strain is credited for the current change, and a charge channel is predicted for large strain, which gives explanation for the observed gigantic enhancement of light emission efficiency in experiments.

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