Development of hybrid photonic and plasmonic light management interfaces for thin film semiconductor devices

Nasser, Hisham
Hydrogenated amorphous silicon (a-Si:H) is a versatile and an attractive material of photovoltaics whose manufacturing has reached an immense and advanced level of maturity. Owing to its moderate conversion efficiency compared to its crystalline counterparts, it should target either power plants with miniature installation cost or applications with added value like building-integration. Since this photovoltaic technology is based on very thin films of a weakly light-absorbing material, light-management is, and always has been, a vital and indispensable aspect of the a-Si:H thin film solar cells technology. The highest conversion efficiencies of a-Si:H solar cells produced today basically involve light trapping approaches which employ randomly textured transparent substrate and a highly reflective rear contact. Obtaining new alternative approaches for light management in a-Si:H thin film solar cells is a great challenge. In this thesis, I propose to use plasmonic metal nanoparticles to enhance the light absorption in a-Si:H thin film solar cells. In the first part of this thesis, I demonstrate fabrication of plasmonically active interface consisting of silver nanoparticles (AgNPs) embedded in aluminum doped zinc oxide (Al:ZnO) that has the potential to be used at the front surface and at the back reflector of a thin film solar cell to enhance light-trapping and increase conversion efficiency. Then several single and double plasmonically active interfaces embedded in dielectric spacer thin films of different dielectric constant were successfully constructed and integrated to the front and at the rear device-quality a-Si:H thin films to investigate their light management potentials in terms of enhanced spectral dependence of photocurrent driven by a constant bias in the a-Si:H thin films use as indicators for an effective plasmonic effect. Single plasmonic interfaces exhibit plasmonic resonances whose frequency is redshifted with increasing particle size and with the thickness of a dielectric spacer layer. Double plasmonic interfaces consisting of two different particle sizes exhibit resonances consisting of double minima in the transmittance spectra. I investigate the enhancement of photocurrent in a-Si:H as a function of nanoparticle size and spacer layer thickness placed to the front and at the rear of the a-Si:H absorber. By comparing the photocurrent enhancement due to plasmonic interfaces integrated to the front and at the rear of a-Si:H thin films, we were able to judge that the true position of plasmonic AgNPs is at the rear of a-Si:H and with an optimum spacer layer of at most 30 nm thick film. A new advanced light trapping concept is constructed for the first time. In this concept, I merge the scattering potentials of Al:ZnO surface texturing and AgNP plasmonics in a single light trapping interface. The results show that surface texturing by wet etching of Al:ZnO combined with AgNPs produces the highest optical extinction of a-Si:H thin film at the band edge and the measured photocurrent shows a clear increase not only at AgNPs resonance wavelength but over the entire wavelength range. In parallel to the study related to the integration of plasmonic structures in a-SiH: thin films; the effect of SiO2 spacer layer thickness on the optical response of AgNPs of potential integration in crystalline silicon solar cells has been investigated. By carefully studying the thickness of the spacer layer, I have identified the critical thickness that defines the border between plasmonic and photonic regimes.


Fabrication of silicon nanowires by electroless etching and investigation of their photovoltaic applications
Özdemir, Barış; Ünalan, Hüsnü Emrah; Turan, Raşit; Department of Metallurgical and Materials Engineering (2011)
Silicon is the most important semiconducting material for optoelectronics owing to its suitable and tunable physical properties. Even though there are several alternatives, silicon based solar cells are still the most widely produced and commercially feasible system. Extensive efforts have been spent in order to increase the efficiency and decrease the cost of these systems. The studies that do not focus on replacement of the semiconducting material, mostly concentrate on the developments that could be brou...
Investigation of material properties of magnetron sputtered CuAg-In-Se thin films
Güllü, Hasan Hüseyin; Parlak, Mehmet (null; 2016-09-23)
Thin films of copper based chalcopyrite absorber materials are attracting the attention of many researchers because of their favorable optoelectronic properties and good stability makes them suitable for photovoltaic and optoelectronic device applications. These compounds are particularly suitable for making p-n hetero-junctions with the II-VI compounds. Therefore, the utilization of I-III-VI2 group of chalcopyrite semiconductors has been reported in the literature for application in thin film solar cells. ...
Production and characterization of carbon-silicon nanocomposite anode materials for secondary lithium batteries
Miser, Burcu; Aydınol, Mehmet Kadri; Parlak, Mehmet; Department of Micro and Nanotechnology (2017)
Amongst other anode materials, silicon has the highest capacity (for Li22Si5: 4200 mAh.g-1), whereas; the commonly used graphite has only a capacity of 320 mAh.g-1. Although this property of silicon makes it a worthwhile subject, there are technical issues which makes it difficult for commercial use. In this study, the aim is to investigate methods of producing silicon anode materials from a readily available powder via top down nano-particle forming methods for next generation lithium ion batteries which h...
Atomic-layer-deposited zinc oxide as tunable uncooled infrared microbolometer material
Battal, Enes; Bolat, Sami; TANRIKULU, MAHMUD YUSUF; OKYAY, Ali Kemal; Akın, Tayfun (2014-11-01)
ZnO is an attractive material for both electrical and optical applications due to its wide bandgap of 3.37eV and tunable electrical properties. Here, we investigate the application potential of atomic-layer-deposited ZnO in uncooled microbolometers. The temperature coefficient of resistance is observed to be as high as -10.4%K-1 near room temperature with the ZnO thin film grown at 120 degrees C. Spectral noise characteristics of thin films grown at various temperatures are also investigated and show that t...
Fabrication of SiO2-stacked diamond membranes and their characteristics for microelectromechanical applications
Bayram, Barış (Elsevier BV, 2011-04-01)
Diamond is a promising microelectromechanical systems (MEMS) material due to its high Young's Modulus and very large thermal conductivity. In this work, ultrananocrystalline diamond was stacked between silicon dioxide to form thermally-stable and robust membranes. These SiO2-stacked diamond layers were processed into MEMS-compatible membranes. For comparison, membranes composed of only SiO2 were fabricated as well. The structural characteristics of these membranes are compared and analyzed for membranes of ...
Citation Formats
H. Nasser, “Development of hybrid photonic and plasmonic light management interfaces for thin film semiconductor devices,” Ph.D. - Doctoral Program, Middle East Technical University, 2015.