Coalescence during epitaxial lateral overgrowth of (Al,Ga)N(1 1 .2) layers

Abstract Epitaxial lateral overgrowth is reported for semi-polar (Al,Ga)N(1 1 .2) layers. The mask pattern consisted of periodic stripes of SiO 2 oriented parallel to either the GaN[1  1  .0] or the GaN[ 1 1  .1] direction. Lateral growth occurred either along GaN[ 1 1  .1] or along GaN[ 1  1 .0]. For growth along the [ 1  1 .0] direction, coalescence was achieved for layer thicknesses >4 μm. However, planarization was not observed yielding extremely corrugated surfaces. For growth in [ 1 1  .1] direction, coalescence was delayed by a diminishing lateral growth rate. Growth of AlGaN during ELOG resulted in coalescence. Improvement in crystal quality of such buffer layers for the growth of InGaN/GaN quantum wells was confirmed by X-ray diffraction and photoluminescence spectroscopy.