Fabrication of Zinc Nitride Thin Films using RF Magnetron Sputtering Deposition for Optoelectronic Applications

Zinc nitride thin films possess a small optical band gap with direct transition, low resistivity, high mobility and carrier concentration. Therefore, it may be suitable as an optoelectronic material for infrared sensors, smart windows and energy conversion devices. The objective of this work is to grow zinc nitride thin films using RF magnetron sputtering, understand its mechanical, optical, and electrical properties, and investigate its performance as light sensing devices.Synthesis and characterization of zinc nitride thin films has been investigated in this work. An RF magnetron sputtering deposition was employed to synthesize zinc nitride thin films using pure metal zinc target in either N2-Ar or N2-Ar-H2 mixtures. The microstructural, optical and electrical characterizations of the representative films were investigated with stylus profilometry, XRD, AFM, SEM, TEM, UV-VIS-NIR double beam spectrometry, and Hall effect measurement. The photoresponse of the zinc nitride photoconductors was also studied under the irradiation of white light and NIR light. The as-deposited zinc nitride thin films were relatively soft and densely packed with smooth surface. It possesses a narrow optical band gap in the NIR range with direct transition. The zinc nitride showed n-type conductivity with low resistivity and high carrier concentration. To study the RF discharge power effect, the zinc nitride thin films were synthesized at different discharge powers densities. With discharge power density increasing, the film deposition rate increased, and the zinc nitride films acquired better crystalline structure, smaller optical band gap and less oxygen contaminations. After thermal annealing at moderate temperatures in either air or O2, the annealed zinc nitride thin films were photoconductive under irradiation of both NIR light and white light. The largest photoresponse and fastest response times were measured at the room temperature for the zinc nitride thin films annealed at 300 degree in the air.Hydrogen inclusion can modify the electrical and optical properties of crystalline semiconductor films by introducing impurity donor states. The ZnNx:H films deposited in N2-Ar-H2 mixture acquired less oxygen contamination and higher relative nitrogen atom concentration than the ZnNx films deposited in N2-Ar mixture. The as-deposited ZnNx:H films showed a clear photonic behavior under white light irradiation, and the annealed ZnNx:H films exhibited a pronounced change in resistance under both white light and NIR light irradiation comparing to the annealed ZnNx films. This was the first time to report photoresponse of zinc nitride thin films fabricated by reactive sputtering method. The photoconductivity was gradually improved by optimization of deposition conditions, annealing conditions and film compositions

Name thesis:degree_name

Doctor of Philosophy in Engineering

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

College of Engineering

Grantor dc:publisher

University of Toledo

Year dc:date

2012

Author dc:creator

• Wen, Ting

Contributors dc:contributor

• Jayatissa, Ahalapitiya

• Mechanical Engineering
• Nanotechnology

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=toledo1353108228

OAI identifier oai:identifier

oai:etd.ohiolink.edu:toledo1353108228