Investigation of novel optoelectronic properties and devices based on semiconductors and biomaterials
Date Issued
2014
Date
2014
Author(s)
Wang, Cih-Su
Abstract
In this dissertation, we have designed novel optoelectronic devices based on ZnO, SnO2 nanostructures combining with metal, semiconductor nanoparticles, and biomaterials. In physical way, we not only discovered many fruitful and interesting optoelectronic properties, but also studied and discussed the potentials for the diversified applications in the future. Our results are classified as 5 main topics and summarized as the followings: 1. Surface-Plasmon-Enhanced Ultraviolet Random Lasing from ZnO Nanowires Assisted by Pt Nanoparticles We report a surface-plasmon-enhanced random laser emission from highly disordered ZnO nanowires with the assistance of Pt nanoparticles. The underlying mechanism of the enhanced lasing efficiency can be attributed to the energy transfer from Pt nanoparticles to ZnO nanowires due to the strong local field induced by the surface plasmon resonance of Pt nanoparticles. Furthermore, the Pt nanoparticles can serve as an excellent scattering medium, which enormously increases the multiple scattering probability experienced by the random cavity modes. Our strategy provided here is very useful for creating highly efficient optoelectronic devices. 2. Lighting Up the Ultraviolet Laser Action from SnO2 Nanowires Assisted by Chicken Albumen A new approach is proposed to light up band-edge stimulated emission arising from a semiconductor with dipole-forbidden band-gap transition. To illustrate our working principle, here we demonstrate the feasibility on the composite of SnO2 nanowires (NWs) and chicken albumen. SnO2 NWs, which merely emit visible defect emission, are observed to generate a strong ultraviolet fluorescence centered at 387 nm assisted by chicken albumen at room temperature. In addition, a stunning laser action is further discovered in the albumen/SnO2 NWs composite system. The underlying mechanism is interpreted in terms of the fluorescence resonance energy transfer (FRET) from the chicken albumen protein to SnO2 NWs. More importantly, the giant oscillator strength of shallow defect states, which is served orders of magnitude larger than that of free exciton, plays a decisive role. For a deeper verification of our proposed mechanism, the laser action has been characterized by strongly scattering system made with Au nanoislands and both dense and sparse NWs. Our approach therefore shows that bio-materials exhibit a great potential in applications for novel light emitters, which may open up a new avenue for the development of bio-inspired optoelectronic devices. 3. Enhancement of Photocurrent Gain Based on Type-II Band Alignment from a Single SnO2 Nanowire Decorated with TiO2 Nanoparticles The high sensitivity of a photodetector in the UV range based on composites consisting of a single SnO2 nanowire (NW) and TiO2 nanoparticles (NPs) has been demonstrated. The underlying mechanism is attributed to the spatial separation of photogenerated electrons and holes due to the charge transfer arising from type-II band alignment between TiO2 NPs and SnO2 NW. The enhanced spatial separation effect prolongs the lifetime of photoinduced electrons and consequently increases the photoresponse gain. Our results should be very useful for creating high-efficiency photodetectors with a broad band photoresponse spectrum. 4. Biologically Inspired Flexible Quasi-Single-Mode Random Laser: An Eminent Integration of Pieris canidia Butterfly Wing and Semiconductors Photonic amorphous structures of natural biomaterial membranes have great potentials to serve as resonance cavities to generate ecological friendly optoelectronic devices with low cost. To achieve the first attempt for the illustration of the underlying principle, the Pieris canidia butterfly wing was embedded with ZnO nanoparticles. Quite interestingly, it is found that the bio-inspired quasi-single-mode random laser can be achieved by the assistance of the skeleton of the membrane, in which ZnO nanoparticles act as emitting gain media. Such unique characteristics can be interpreted well by the Fabry-Perot resonance existing in the window-like photonic amorphous structure of butterfly wing. Due to the inherently promising flexibility of butterfly wing membrane, the laser action can still be maintained during the bending process. Our demonstrated approach not only indicates that the natural biological structures can provide effective scattering feedbacks but also pave a new avenue towards designing bio-controlled photonic devices. 5. Electrically Driven Random Laser Memory The electrical reading of conventional memory array is usually in serial sequence, which limits the maximum data throughput. This hurdle can be overcome by optically readable memory devices. Here, we design and demonstrate the first electrically driven random laser diode with nonvolatile resistive random access memory (RRAM) functionality. To illustrate our working principle, a metal-insulator-semiconductor (MIS) structure based on Pt/MgO/ZnO thin film layers is fabricated on indium tin oxide (ITO) glass. The current-voltage curve of the dual-function random laser memory (RLM) device exhibited an excellent electrical bistability with a high ON/OFF current ratio (~107). The random lasing (RL) behavior is simultaneously demonstrated by using electrical pumping with the appearance of sharp-peak emissions and a drastic enhancement of peak intensity. A wide angle-dependent electroluminescence not only reveals its emitting advantage but further supports the origin of random lasers. The first proof-of-concept presentation of RLM possesses several advantages of dual memory and lasing functions, which enables to open up new avenues to practical applications, such as light emitting memories for electrical and optical communication. This new horizon for the realization of all optical memories should therefore be able to attract academic as well as industrial interests.
Subjects
ZnO
SnO2
TiO2
Pt
random laser
memory
photodetector
LED
albumen
butterfly
Pieris canidia
SPR
FRET
Type
thesis
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