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Earth-Abundant Zinc-IV-Nitride Semiconductors

Citation

Coronel, Naomi Cristina (2016) Earth-Abundant Zinc-IV-Nitride Semiconductors. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9CF9N28. http://resolver.caltech.edu/CaltechTHESIS:05252016-080726422

Abstract

This investigation is motivated by the need for new visible frequency direct bandgap semiconductor materials that are abundant and low-cost to meet the increasing demand for optoelectronic devices in applications such as solid state lighting and solar energy conversion. Proposed here is the utilization of zinc-IV-nitride materials, where group IV elements include silicon, germanium, and tin, as earth-abundant alternatives to the more common III-nitrides in optoelectronic devices. These compound semiconductors were synthesized under optimized conditions using reactive radio frequency magnetron sputter deposition. Single phase ZnSnN2, having limited experimental accounts in literature, is validated by identification of the wurtzite-derived crystalline structure predicted by theory through X-ray and electron diffraction studies. With the addition of germanium, bandgap tunability of ZnSnxGe1-xN2 alloys is demonstrated without observation of phase separation, giving these materials a distinct advantage over InxGa1-xN alloys. The accessible bandgaps range from 1.8 to 3.1 eV, which spans the majority of the visible spectrum. Electron densities, measured using the Hall effect, were found to be as high as 1022 cm−3 and indicate that the compounds are unintentionally degenerately doped. Given these high carrier concentrations, a Burstein-Moss shift is likely affecting the optical bandgap measurements. The discoveries made in this thesis suggest that with some improvements in material quality, zinc-IV-nitrides have the potential to enable cost-effective and scalable optoelectronic devices.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Semiconductors, Earth-Abundant, Compound, Nitride, ZnSnN2, ZnGeN2, Photovoltaics, Optoelectronics, Sputtering
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Materials Science
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Atwater, Harry Albert
Thesis Committee:
  • Atwater, Harry Albert (chair)
  • Greer, Julia R.
  • Bhattacharya, Kaushik
  • Minnich, Austin J.
Defense Date:15 June 2015
Funders:
Funding AgencyGrant Number
U.S. Department of EnergyUNSPECIFIED
Dow Chemical CompanyUNSPECIFIED
Record Number:CaltechTHESIS:05252016-080726422
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:05252016-080726422
DOI:10.7907/Z9CF9N28
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1002/adma.201304473Related DocumentArticle: Bandgap Tunability in Zn(Sn,Ge)N2 Semiconductor Alloys
http://dx.doi.org/10.1002/adma.201204718Related DocumentArticle: Structural and Optoelectronic Characterization of RF Sputtered ZnSnN2
http://dx.doi.org/10.1109/PVSC.2012.6318259Related DocumentConf. paper: Earth-abundant ZnSnxGe1−xN2 alloys as potential photovoltaic absorber materials
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9746
Collection:CaltechTHESIS
Deposited By: Naomi Coronel
Deposited On:25 May 2016 23:32
Last Modified:25 May 2016 23:56

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