Gas source molecular beam epitaxy growth of GaN on C-, A-, R- and M-plane sapphire and silica glass substrates

GaN layers are grown on C-; A-, R- and nd-plane sapphire substrates by gas source molecular beam epitaxy (MBE). The c-axis of GaN is perpendicular to the surface plane and photoluminescence spect;ra exhibit strong and sharp (full width at half maximum less than or equal to 39 meV at 77 K) excitonic emission without deep level emission for all cases. GaN layers grown on silica glass substrates also have the c-axis perpendicular to the surface, although they are poly-crystalline. They exhibit an n-type conduction with an electron concentration of 7 x 10(-16) cm(-3) and a mobility of 23 cm(2)/Vs, They also exhibit strong photoluminescence comparable to that of GaN grown on sapphire substrates, although showing a wide spectral half width (245 meV at 77 K). GaN layers grown on glass substrate is considered promising for fabrication of large area and low cost light emitting devices and solar cells.