Surface structures and growth kinetics of InGaN(0001) grown by molecular beam epitaxy

The surface structures and growth kinetics of InGaN(0001) are studied. It i s well known that during molecular beam epitaxy GaN surfaces undergo a smoo th to rough transition when the growth condition is switched from Ga rich t o N rich. It is found here that indium atoms have only a small effect on th is transition when deposited on GaN(000 (1) over bar), but when deposited o n GaN(0001) the indium acts as a surfactant and greatly extends the regime of smooth growth. Near the smooth/rough transition of InGaN(0001) growth, a bright root 3x root 3 reconstruction is observed at growth temperature. Th e formation kinetics of this reconstruction are studied in detail. Scanning tunneling microscopy and total energy computations are used to study the s tructure of InGaN(0001) surfaces under metal rich conditions. Indium is fou nd to occupy the top two atomic layers of the crystal; its incorporation in the second layer produces significant strain, leading to the formation of small pits on the surface and increased indium concentration inside and aro und the pits. (C) 2000 American Vacuum Society. [S0734-211X(00)07004-9].