Simulation of Electromagnetic and Semiconductor Characteristics of Microstructures for Three-Dimensional Integrated Circuits and Photovoltaics
Date Issued
2015
Date
2015
Author(s)
Lin, Leo Jyun-Hong
Abstract
Substrate coupling in 3D-ICs using Cu through silicon vias (TSVs) is a predicament widely documented in recent literature. Yet discussions remain limited to the electromagnetic framework, such that a complete understanding of noise propagation and absorption is hampered. Chapter 2 thoroughly examines these phenomena in TSVs from the integrated perspectives of semiconductor physics and EM Theory and investigates the noise reduction method using the combination of p+ guard-ring and grounded TSV via 3D device simulation. Both 2D electromagnetic and electrical semiconductor simulations are performed sequentially in this study in order to better understand the structural principles of thin-film crystalline solar cells with back surface field and blaze diffractive grating. In the absence of adequate approximations for blazed gratings, we simulate silicon solar cells electromagnetically and electrically in order to deal with the geometrical complexity produced by the blazed grating with a BSF on top of it. Thin-film crystalline silicon solar cells (TF-c-Si SCs) typically exhibit poor quantum efficiency both at shorter wavelengths and longer wavelengths with sharp drops in spectral response. Longer wavelength spectral response (from 0.6 μm to 1.2 μm) is addressed here first by considering the influence of blaze gratings on the enhancement of effective optical absorption in thin-film crystalline silicon (TF-c-Si) solar cells. The effect of the back surface field layer (BSF) in terms of improving minority carrier collection is also taken into account. In the 2D electromagnetic simulation, polarization dependent two-dimensional (2D) numerical simulations based on rigorous coupled wave analysis (RCWA) and finite element method (FEM) are implemented for the optimization of optical absorption of the solar cell structure. A rather large tolerance in design parameters of the optimized blaze grating structure was found. The optimized blaze grating structures help in improving the cell efficiency, especially for weak absorption thin cell structures. The enhancement of equivalent optical path length reveals the efficient light trapping effect caused by the diffractions of the blaze grating structures, especially in the longer wavelength range. In the electrical semiconductor simulation, the BSF, which arises from the heavy acceptor doping that creates the concentration gradient, is set atop the blaze grating in order to provide an extra small drift field for the collection of minority electrons. Incorporating the optimized antireflection coating along with a BSF layer and a blaze-grating in the 2 μm cell doubles cell efficiency. The use of blazed gratings in thin-film solar cells, which can be performed upon silicon by means of lithography and ion-beam etching, is promising for low cost and high-efficient solar cell applications. Optical design in enhancing optical absorption of group-III-nitride- and multiple quantum well-based GaN/InxGa1-xN/cSi dual-junction tandem solar cells with triangular diffraction grating is simulated and optimized by using combined two-dimensional rigorous coupled wave analysis and transfer matrix methods. This work thoroughly examines these phenomena of optical absorption affected by antireflection coatings, multiple thin-film layers and diffraction gratings with the integrated perspectives of semiconductor physics and electromagnetic theory for the first time. An improvement of 58% in absorption compared to the prototype SC is obtained which means more than 80 % of incoming light (hυ > EgSi) can be harvested in this thin-film (< 4 μm in total) design.
Subjects
Three-Dimensional Integrated Circuits
Cu Through Silicon Vias (TSVs)
Photovoltaics
Blaze Gratings
Back Surface Field (BSF)
Electromagnetic Characteristics
Semiconductor Characteristics
Simulation
Microstructures
Gallium Indium Nitride
Silicon
Anti-Reflection Coating (ARC)
SDGs
Type
thesis
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