The growth of low-defect thick films of AlN and AlGaN on trenched

AlGaN/sapphire templates was studied using migration enhanced lateral epitaxial

overgrowth. 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 a cw output power of 1.6mW at 50mA current; with an

extrapolated lifetime above 5000h. The results demonstrated a substantial

improvement in the device lifetime; due mainly 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