Publications
Atmospheric pressure growth of bulk GaN for substrates for high temperature electronics and optoelectronics
Gallium nitride is a promising material for numerous optoelectronic and high power, high frequency, and high temperature applications (e.g., synthetic aperture radar, chem.-bio sensing, utility power switching, down-hole sensors, water purification, solar-blind detectors, etc.). While many GaNbased opto/electronic devices have been demonstrated, all applications that require high power operation suffer in performance and reliability from the lack of native substrates. The advent of a scalable, manufacturable, and affordable process for growth of bulk GaN for substrates would greatly advance these technologies. Melt growth is impractical as it requires temperatures >1600°C and pressures >45,000 atmospheres, and is kinetically slow. A novel materials synthesis technique is described that takes place in a molten salt at atmospheric pressure. The salt is a relatively good solvent for molecular GaN and an excellent solvent for its ionic precursors, which can be continuously created electrochemically, thus enabling boule growth. This flexible, unique, and interdisciplinary approach solves the kinetic, thermodynamic, scalability, cost, and manufacturability issues inherent in alternative methods. Electrochemical growth of gallium nitride crystals at atmospheric pressure at 450°C has been demonstrated, and options are discussed for improving and extending the technique to production of large area boules. Copyright © 2006 International Microelectronics And Packaging Society.