A Multi-topic International Conference
UNCC_Honet logo_HONET    
11th HONET-PfE
Charlotte, North Carolina, USA
December 15 - 17, 2014 
Dr. Nikolaus Dietz
Professor of Physics,
Dept. Physics and Astronomy
Georgia State University, Atlanta, GA                  
Email: ndietz@gsu.edu

Development and integration of indium-rich group III-nitrides for energy generation / utilization


  Confined indium-rich ternary In1-xGaxN (InGaN) alloys and heterostructures over a wide compositional range are essential in high-efficient spectral agile light sources, multi-junction photovoltaic solar cells as well as advanced high-speed optoelectronics. The presently encountered processing limitations for low-pressure MOCVD growth of ternary group III-nitride restrict the indium incorporation and formation of InGaN heterostructures to a narrow composition range, with a rapid degradation of the materials quality for alloys with indium content above 25%. The exploration of potential pathways to stabilize alloys with higher indium content and to reduce the growth temperature gap between the binaries InN and GaN lead to the assessment of superatmospheric pressure MOCVD (also denotes as high-pressure chemical vapor deposition, HPCVD), as well as to plasma-assisted and/or migration-enhanced MOCVD processes.
  This presentation will discuss the superatmospheric MOCVD growth of indium-rich InGaN alloys and the influence of the pulse separations on the phase purity and stability of indium-rich InGaN epilayer and resulting structural and optical properties. As shown, this approach narrows the growth process window by increasing the growth temperature of indium-rich alloys as function of reactor pressure. A second potential pathway to stabilize indium-rich InGaN is by kinetic means, a concept explored in plasma-assisted MOCVD of group III-nitrides. Initial results will be presented and discussed for GaN growth.

Short Biography:

  Nikolaus Dietz is a Professor of Physics at Georgia State University (GSU) in Atlanta. His areas of expertise include: radiation interactions with matter; the growth, materials property analysis and defect characterization of photovoltaic group II-VI and I-III-VI2 compound semiconductors; the epitaxial thin film growth of group III-phosphide and group III-nitride compound semiconductors by chemical beam epitaxy, low-pressure and superatmospheric CVD and plasma-assisted MOCVD - and their physical properties characterization; the real-time optical thin-film growth diagnostic and process control; and the characterization of linear/nonlinear optical materials properties. Present research focuses on the development and exploration of new approaches for the fabrication of ternary and quaternary group III-nitrides/phosphides heterostructures of relevance in nanophotonics, optoelectronics, high-efficient photovoltaics, and photocatalytic devices. Dr. Dietz holds several patents and has published more than 140 papers in peer-reviewed journals as well a number of book chapters.

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