The growth of low-defect thick films of AlN and AlGaN on trenched AlGaN/sapphire templates, using migration enhanced lateral epitaxial overgrowth, was reported. Incoherent coalescence-related defects were alleviated by controlling the tilt angle of growth fronts and by allowing Al adatoms sufficient residence time to incorporate at the most energetically favorable lattice sites. Deep ultra-violet light emitting diode structures (310nm) deposited over fully coalesced thick AlN films exhibited cw output power of 1.6mW at 50mA current with extrapolated lifetime in excess of 5000h. The results demonstrated a substantial improvement in device lifetime, due primarily to the reduced density of growth defects.

Migration Enhanced Lateral Epitaxial Overgrowth of AlN and AlGaN for High Reliability Deep Ultraviolet Light Emitting Diodes. R.Jain, W.Sun, J.Yang, M.Shatalov, X.Hu, A.Sattu, A.Lunev, J.Deng, I.Shturm, Y.Bilenko, R.Gaska, M.S.Shur: Applied Physics Letters, 2008, 93[5], 051113