Abstract

We report on the growth of semipolar (112¯2) AlGaN in the entire composition range on (101¯0) sapphire by metal–organic vapor phase epitaxy. Growth rates increase linearly with the metal–organic supply and have been realized up to 2.5μm/h. The Al content determined by photoluminescence and transmission measurements depends linearly on the Al/Al+Ga ratio in the gas phase. The growth rate and the Al incorporation are higher for (112¯2) AlGaN than for (0001) AlGaN. This is attributed to different adatom mobility and desorption. The in-plane relationship of (112¯2) AlGaN is [1¯100]AlGaN∥[12¯10]Sap. and [1¯1¯23]AlGaN∥ [0001]Sap., as typical for semipolar nitrides on m-plane sapphire. For Al contents up to 60% triangle-like structures dominate the surface. For Al contents above 70% it transforms into an undulation along [1¯100] and additional dot-like structures. The smoothest surface morphologies with a rms roughnesses of 2nm were achieved for Al mole fractions of ∼50%.

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