Contribution to the modeling and optimization of new optoelectronic devices

FERHATI, Hichem (2019) Contribution to the modeling and optimization of new optoelectronic devices. Doctoral thesis, Université de Batna 2.

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Optoelectronic devices are of vital technological importance because of their application in various fields including optical communication, environment monitoring and clean renewable energy sources. Integrated optoelectronic devices provide new opportunities toward dealing with the steady requirement of large bandwidth of nextgeneration optical interconnections technology. In spite of this tremendous success, there are many challenges associated with photoreceiver devices such as huge overhead in power consumption and relatively low sensitivity. On the other hand, the advanced thin-film photovoltaic based on kesterite technology has been enabling great promise in meeting demands of carbon-neutral energy. However, the developed CZTS solar cell structures are still challenging and their efficiency remains far from that offered by the Silicon-based technology. The work presented in this dissertation includes the development of new optoelectronic devices and their applications in advanced optical interconnects and photovoltaic. The discrepancy between the advanced nanoelectronic and photonic devices is investigated, with a focus on the photoreceiver that determines the power budget of optical interconnects. The goal of this thesis is also to explore the possibility to overcome the most critical problems of the CZTS solar cell with the aim of achieving superior conversion efficiencies. Based upon these topics, the thesis is divided into the following parts First, the state-of-the-art of the optoelectronic devices including photodetectors, phototransistors and kesterite solar cell will be presented. Afterwards, the basic photodetection mechanism and key device figure of merits are described. Finally, the recent progress in the CZTS solar cell and their advanced elaboration techniques are reviewed in detail. Next, metaheuristic techniques and their potential for treating many engineering problems are presented. An overview of various metaheuristic algorithms such as genetic algorithm (GA), particle swarm optimization (PSO) techniques and their derivatives are discussed in details, indicating its potential application for optimizing novel optoelectronic devices. Thereafter, two novel UV photodetector designs are proposed and analytically investigated in order to achieve the dual-benefit of high-performance photoreceivers and reduced power consumption. The first one relies on combining front glass texturization to enhance the device performance. While the second design aims at developing self-powered photodetectors by using dual material aspect. The proposed designs are optimized using PSO-based approach, where improved device FoMs are achieved. Afterwards, new CMOS compatible phototransistor designs are introduced in the second part of this thesis. We focus on improving the device sensitivity and reduce its fabrication cost by proposing a new design based on the junctionless aspect. The proposed structure is then optimized using GA technique, where it offers an outstanding capability achieve high-performance phototransistor. We also propose in this chapter a new optically controlled tunneling field effect transistor (OC-TFET) based on SiGe/Si/Ge Hetero-channel in order to enhance the optical commutation speed and reduce power consumption. The investigated phototransistor designs share the ultra-sensitivity and weak signal detection characteristics, which enables reducing the power from the emitter stage and thereby decreasing the power budget. This thesis defines also a path to enable improved efficiency values of kesterite solar cell by appropriately engineering the absorber layer. Firstly, a graded band-gap aspect is introduced to avoid the recombination losses and enhance the carrier separation. Secondly, intermediate metallic sub-layers are introduced in the CZTS region to simultaneously achieving reduced optical losses and lower series resistance. PSO-based approach is conducted with the aim of maximizing the power efficiency. The physical reasons that govern the efficiency enhancement are also discussed. Finally, the role of introducing an intermediate Indium Tin Oxide (ITO) thin-film in improving the Au/Si Schottky Barrier Diode (SBD) electrical and thermal stability performances is experimentally analyzed. The Au/ITO/Si/Au structures with different ITO thicknesses were fabricated using RF magnetron sputtering technique. The current-voltage (I-V) characteristics of the elaborated structures are studied. Moreover, the effect of the annealing process on the device performance is investigated. Our study shows that the annealed SBD allows avoiding the degradation related-heating effects

Item Type: Thesis (Doctoral)
Uncontrolled Keywords: Optoelectronic; Photodetector; Self-powered, texturization, Phototransistor; Junctionless; Tunneling; Power consumption; Optical interconnects; Photovoltaic; CZTS; Recombination; Efficiency; Graded band-gap; Metallic sub-layers; ITO; Schottky Barrier Diode; thermal stability; annealing; GA; PSO.
Subjects: Technologie > Electronique
Divisions: Faculté de technologie > Département d'électronique
Date Deposited: 09 Jun 2019 10:07
Last Modified: 09 Jun 2019 10:07

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