Synthesis of germanium nanowires by vapor transport and fabrication of fully transparent flexible photodetectors

Download

index.pdf

Date

2012

Author

Aksoy, Burcu

Metadata

Show full item record

Item Usage Stats

271
views

92
downloads

Nanomaterials are widely investigated by researches and because of their unique properties they have been utilized in many different devices. Nanowires are one of these materials which show deviated mechanical, chemical, physical and optical, properties from their bulk counterparts. These deviations in properties of the nanowires are based on both their high surface to volume ratio and quantum confinement effect. Lately optical properties of nanowires have received great attention as they also exhibit good light sensitivity. Germanium is a semiconductor, which has been used widely as an active material in infrared light detectors. Due to excellent light detection of germanium its nanostructures have also been widely studied in optoelectronic devices. Germanium nanowires have been used in many devices such as field effect transistors, diodes, field emitters and photodetectors. Synthesis of high quality and high aspect ratio germanium nanowires could make important contributions to these devices. There are several synthesis methods for germanium nanowires. These are electrochemical etching, solvothermal, supercritical v fluidic, laser ablation, chemical vapor deposition and vapor transport methods. Among these methods, high quality, single crystalline, defect free germanium nanowires using accessible solid powder precursors could be synthesized with vapor transport method. In the first part of this thesis, germanium nanowire growth with vapor transport method is investigated. One of the most advantageous features of this method is using solid powder precursors instead of toxic gases. Until now, three different kinds of solid germanium precursors have been reported in vapor transport method, all of them are investigated and the resulting nanowires are compared in this thesis. Vapor transport method enables high control over the morphology of the nanowires. The most important parameters which affect the morphology of the nanowires are temperature, pressure and precursor type. Therefore, a detailed parametric study is provided based on these parameters and their effect on the final diameter of the nanowires is determined. The as –synthesized nanowires contain a very thick oxide layer on their surface. Therefore, oxide removal with acid etching is also investigated in this thesis. In the second part of this thesis, utilization of the germanium nanowire networks in fully transparent, flexible and network enhanced photodetectors is investigated. In order to obtain a germanium nanowire network, the as-synthesized nanowires are transferred from growth substrate to the device substrate by sonication and vacuum filtration. Silver nanowires and single walled carbon nanotubes are used as fully transparent electrodes. Both rigid and flexible photodetectors are fabricated and their current-voltage characteristics and photoresponse behaviors with different germanium nanowire densities are determined.

Subject Keywords

Nanowires., Nanostructured materials., Germanium., Optical detectors.

URI

http://etd.lib.metu.edu.tr/upload/12614414/index.pdf
https://hdl.handle.net/11511/21608

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Silicon nanowires for network photodetectors and plasmonic applications Mülazımoğlu, Emre; Ünalan, Hüsnü Emrah; Turan, Raşit; Department of Metallurgical and Materials Engineering (2013) Being the key component of the semiconductor industry, silicon in nanowire form has gained increased attention. In this thesis, vertical arrays of silicon nanowires (Si NWs) have been fabricated with metal assisted etching method (MAE). MAE method is a simple, solution based and low temperature process. In this method, fabricated nanowires inherit the starting wafer characteristics, such as doping type, density and crystal orientation. In the first part, fabricated NWs in network form have been demonstrated...
Effect of substrate type on structural and optical properties of metal nanoparticles for plasmonic applications Tanyeli, İrem; Turan, Raşit; Bek, Alpan; Department of Physics (2011) In this work, the structural and optical properties of metal nanoparticles fabricated on various substrates have been investigated. The particles were fabricated by electron beam lithography (EBL) and dewetting of a thin metal film. The advantages and disadvantages of these two fabrication techniques are discussed by considering the properties of the nanoparticles and the applicability to large area substrates. Being a practical fabrication method, dewetting can be applied to any substrate with either small...
Synthesis, functionalization and characterization of gold nanoparticles Sholanbayeva, Zhanar; Nalbant Esentürk, Emren; Durucan, Caner; Department of Micro and Nanotechnology (2012) Metallic nanoparticles (NPs) with various elemental composition, size, shape and physical or chemical properties has become active field of research. Among all the metal NPs noble metal ones are receiving much attention due to their special optical properties which make them useful for different applications. Noble metal NPs have bright colors resulting from strong surface plasmon resonance absorption usually in the visible region. The colors are size and shape dependent and provide the tuning of optical pr...
Synthesis of gold nanowires with high aspect ratio and morphological purity Dertli, Elçin; Nalbant Esentürk, Emren; Ünalan, Hüsnü Emrah; Department of Micro and Nanotechnology (2012) Metal nanoparticles have unique optical, electrical, catalytic and mechanical properties, which lead them to various applications in nanotechnology. In particular, noble metal nanowires are attracting growing attention due to their potential applications such as in opto-electronic devices and transparent conductive contacts (TCCs). There are two general approaches to synthesize nanowires: template-assisted and solution phase methods. However, these synthesis approaches have various disadvantages. For exampl...
Synthesis of calcium carbonate microspheres via inert gas bubbling for orthopedic applications Oral, Cagatay M.; Caliskan, Arda; Goctu, Yagmur; KAPUSUZ, DERYA; Ercan, Batur (Elsevier BV, 2020-02-15) Calcium carbonate (CaCO3) microspheres consisting of vaterite polymorph have been widely used in biomedical applications. Specifically, vaterite microspheres having hollow cores showed significant potential in drug delivery, however the spontaneous transformation of vaterite to other polymorphs in aqueous environments reduced its controlled in vivo release capability. In this work, calcite and aragonite microspheres having hollow/porous inner cores were synthesized -for the first time-using sodium dodecyl s...

Citation Formats

B. Aksoy, “Synthesis of germanium nanowires by vapor transport and fabrication of fully transparent flexible photodetectors,” M.S. - Master of Science, Middle East Technical University, 2012.