Growth of a Boule of GaN

A recent workshop on wide bandgap semiconductors concluded there is still an urgent need for a GaN single crystal boule. Such a boule would allow the fabrication of single crystal wafers of high quality GaN for the epitaxial growth of high qualitydevices and integrated circuits for numerous applications from short wavelength lasers, high performance transistors to UV/XRay detectors. Astralux, with support from AFSOR and DARPA. has done preliminary work on the growth of GaN single crystals,demonstrating the possibility of fast growth of at least 0.4 mm/hr. More importantly the key problems to overcome for a successful boule growth were clearly identified and the solution to these challenges were defined, before the funding ran out. Now,Astralux aims for a successful multistage attack on this vital problem. First, there is a need to demonstrate a controlled growth rate. Second, the choice of a high quality seed is critical. Third, the distribution of reactants over the growth area mustbe properly controlled. Finally, a more powerful rf generator must be set up. Astralux proposes to do this final stage with the collaboration of a large U.S. corporation.A single crystal boule of high quality GaN will allow production of wafers of high quality GaN for the epitaxial growth of devices and ICs.