Dr. Tom Nelson Oder Profile

Dr. Tom Nelson Oder

at Youngstown State Univ

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Publications (4)

Proceedings Article | 20 October 2004 Paper

III-nitride blue and UV photonic-crystal light-emitting diodes

Jagat Shakya, Kyoung Hoon Kim, Tom Oder, Jing Yu Lin, Hong Xing Jiang

Proceedings Volume 5530, (2004) https://doi.org/10.1117/12.565632

KEYWORDS: Light emitting diodes, Near field scanning optical microscopy, Ultraviolet radiation, Ultraviolet light emitting diodes, Photonic crystals, Blue light emitting diodes, Gallium, Optical pumping, Near field optics, Electroluminescence

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Proceedings Article | 11 June 2002 Paper

Time-resolved photoluminescence studies of Al-rich AlGaN alloys

Jing Li, Ki-Bum Nam, Tom Oder, KyoungHoon Kim, M. Nakarmi, Jing Lin, Hongxing Jiang

Proceedings Volume 4643, (2002) https://doi.org/10.1117/12.470429

KEYWORDS: Aluminum, Doping, Silicon, Magnesium, Gallium, Luminescence, Temperature metrology, Gallium nitride, Excitons, Metalorganic chemical vapor deposition

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Si-doped n-type Al_xGa_1MINxN alloys with x up to 0.5 and Mg-doped p-type Al_xGa_1-xN alloys with x up to 0.27 were grown by metal-organic chemical vapor deposition (MOCVD) on sapphire substrates. For the n-type Al_xGa_1-xN, we achieved highly conductive alloys for x up to 0.5. An electron concentration as high as 1x10¹⁸cm^-3 was obtained in Si-doped Al_0.5Ga_0.5N alloys with an electron mobility of 16 cm$_2)Vs at room temperature, as confirmed by Hall-effect measurements. Our results also revealed that the conductivity of Al_xGa_1-xN alloys continuously increases with an increase of Si doping level for a fixed value of Al content (X<0.5), the conductivities of Al_xGa_1-xN alloys decrease with increasing Al content for a given doping level; the critical Si-doping concentration needed to convert insulating Al_xGa$1-x)N with high Al contents (X>=0.4) to n- type conductivity is about 1 x 10¹⁸cm^-3. Time- resolved photoluminescence studies carried out on these materials have shown that Si-doping reduces the effect of carrier localization in Al_xGa_1-xN alloys and a sharp drop in carrier localization energy occurs when the Si doping concentration increases above 1x10¹⁸cm^-3, which directly correlates with the observed electrical properties. For the Mg-doped Al_xGa_1-xN alloys, p-type conduction was achieved for x up to 0.27, as confirmed by variable temperature Hall measurements. Emission lines of band-to-impurity transitions of free electrons with neutral Mg acceptors as well as localized excitons have been observed in the p-type Al_xGa_1-xN alloys. The Mg acceptor activation energies E_A were deduces from photoluminescence spectra and were found to increase with Al content and agreed very well with those obtained by Hall measurements. From the measured activation energy as a function of Al content, E_A versus x, the resistivity of Mg-doped Al_xGa_1-x with high Al contents can be deduced. Our results have also shown that PL measurements provide direct means of obtaining E_A especially where this cannot be obtained accurately by electrical methods due to high resistance of p-type Al_xGa_1-xN with high Al content.

Proceedings Article | 11 June 2002 Paper

Exciton-polariton propagation in AlGaN/GaN quantum-well waveguides probe by time-resolved photoluminescence

Tom Oder, Jing Li, Jing Lin, Hongxing Jiang

Proceedings Volume 4643, (2002) https://doi.org/10.1117/12.470430

KEYWORDS: Waveguides, Gallium nitride, Light wave propagation, Excitons, Semiconductors, Polaritons, Diffusion, Wave propagation, Luminescence, Quantum wells

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Proceedings Article | 23 April 2001 Paper

Growth and optoelectronic properties of III-nitride quaternary alloys

Jing Li, Ki-Bum Nam, KyoungHoon Kim, Tom Oder, H. Jun, Jing Lin, Hongxing Jiang

Proceedings Volume 4280, (2001) https://doi.org/10.1117/12.424740

KEYWORDS: Gallium nitride, Aluminum, Indium gallium nitride, Ultraviolet radiation, Quantum efficiency, Sensors, Atomic force microscopy, Optoelectronics, Heterojunctions, Ultraviolet detectors

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