Optical and electronic logic gate with orthogonal inputs

• Main Author: Xu, Cai
• Other Authors: Chen Xiaodong
• Format: Theses and Dissertations
• Language: English
• Published: 2018
• Subjects: DRNTU::Engineering::Materials::Nanostructured materials
• Online Access: https://hdl.handle.net/10356/89677; http://hdl.handle.net/10220/46334
• Institution: Nanyang Technological University

Logic gate is the fundamental for computational operation. With the fast development of information technology, it is necessary to develop the logic operation system at micro or nanoscale. At the meantime exploring different kinds of output signal and incorporating various inputs could significantly extend the potential application of logic gate. This thesis aims to explore both optical and electronic logic gate function with orthogonal inputs, and realize the functions at micro or nanoscale. Our thesis starts from the hypothesis that by employing one system which is sensitive to orthogonal external inputs (optical, electrical and electrochemical), loading different inputs could generate outputs and realize the logic operation. The output value depends on the input and the output signal could be controlled by properly designing the system and materials involved. Another objective is to achieve the logic gates with stable output, even without continuous input provided. Hence, the logic operation does not rely on durative power supply. Memristors and orthogonally switchable molecules were used in the current study toward this goal. Two contributions of the thesis include developing the electronic logic gate and the optical logic gate in novel approaches. Firstly, the electronic logic gate has been successfully demonstrated based on the integration of single nanorod based optoelectronic memory device and electrically switchable memory devices. The memristor based circuit does not rely on continuous input to generate output. Thus, it performs the function of both information storage and logic operation. To achieve such kind of logic gate, firstly the optoelectronic memory device has been developed based on single nanorod device. The device was fabricated based on the photo-sensitive semiconductor CdS. By properly engineering the material interface, the photocurrent can be maintained after removing optical stimulation. Unlike the tradition memory device, the single nanorod based resistive switching memory could keep photocurrent persistently but the information could still be compulsively erased after a specific time horizon. Thus, it demonstrated the function of both information storage (memory) and information protection (self-destructive). The optoelectronic memory device was integrated with an electrically switchable resistive switching memory thereafter to demonstrate the memristor based logic gate function. Due to the characteristics of two components employed, the circuit realized three levels of functions: the fundamental “OR” logic gate, the memorable logic gate and the self-locking logic gate. Secondly, the optical logic gate was designed to generate distinct plasmonic output signal by transforming the orthogonal inputs. The device was prepared by assembling the organometallic molecules, which is responsive to both light illumination and electrochemical stimulation, to the plasmonic active gold nanoparticle arrays. The output signal, which is the plasmon resonance, can be tuned as a result of molecular switch under different stimulations. Thus, the plasmonic logic function has been successfully demonstrated in solid state, and by molecular modulation for the first time.