Ramón Collazo, Principal Investigator

Professor Ramón Collazo, University Faculty Scholar, received his Ph.D. in Materials Science and Engineering from North Carolina State University in 2002. His research focuses on the growth, characterization, and fundamental properties of III-nitride wide-bandgap semiconductors. A recognized expert in metal-organic chemical vapor deposition (MOCVD) and epitaxial growth, he leads efforts to advance high-performance materials for optoelectronic and power device applications. He has received multiple awards for research and mentoring excellence and currently co-directs the Wide-Bandgap Semiconductor Laboratory at NC State.

Faculty Profile

Collazo’s key research areas

Controlled Polarity Engineering in III-Nitrides

Understanding and manipulating polarity in nitrides to enable lateral homojunction devices

Bulk AlN Substrates and Epitaxial Growth

Developing high-quality AlN single crystals and epitaxial thin films for optoelectronics and power devices

Characterization and Device Integration of Wide Bandgap Materials

Linking material characterization (optical, structural, electrical) to device performance in nitrides and oxides

Zlatko Sitar, Principal Investigator

Professor Zlatko Sitar, Kobe Steel Distinguished Professor of Materials Science and Engineering, received his Ph.D. from North Carolina State University in 1990. He is internationally recognized for pioneering work in the synthesis and characterization of wide-bandgap materials, particularly aluminum nitride and gallium nitride. His research has significantly advanced the understanding of crystal growth and defect control in III-nitrides, enabling the development of state-of-the-art electronic and photonic devices. He serves as co-director of the Wide-Bandgap Semiconductor Laboratory at North Carolina State University.

Faculty Profile

Sitar’s key research areas

AlN Crystal Growth and Commercialization

Pioneering high-quality AlN bulk growth and enabling commercialization via HexaTech, Inc.

III-Nitride Epitaxy and Lateral Polarity Devices

Innovative growth of lateral polar structures and devices such as lateral p-n diodes and novel FETs

Wide/Extreme Bandgap Semiconductors and Devices

Developing materials, wafers, and device architectures for deep-UV, power and high-voltage applications

Research Focus: Advancing Wide-Bandgap Semiconductor Materials and Devices

Our areas of expertise include:

• Epitaxial growth and materials development:
  • Metal-organic chemical vapor deposition (MOCVD) of III-nitride semiconductors
  • Bulk crystal growth of aluminum nitride (AlN) and gallium nitride (GaN)
  • Defect reduction, polarity control, and doping engineering
  • Alloy design for next-generation optoelectronic and power materials
• Characterization and device integration:
  • Optical and electrical characterization of III-nitride materials
  • Polarization and strain effects in wide-bandgap semiconductors
  • High-power and high-frequency electronic devices
  • Ultraviolet and deep-UV optoelectronic devices
• Core research goals:
  • Advancing fundamental understanding of wide-bandgap materials
  • Enabling scalable, high-quality nitride substrates and epitaxy
  • Driving innovation in power electronics, solid-state lighting, and quantum technologies

Selected High-Impact Publications

• On the origin of the 265 nm absorption band in AlN bulk crystals — AP Letters
• Progress on n-type doping of AlGaN alloys on AlN single crystal substrates for UV optoelectronic applications — PSSC
• Universal phonon mean free path spectra in crystalline semiconductors at high temperature — Nature
• Growth of AlN/GaN layered structures by gas source molecular‐beam epitaxy — JVST B
• Growth of cubic phase gallium nitride by modified molecular-beam epitaxy — JVST A