Surface reconstructions of cubic gallium nitride „001... grown by radio frequency nitrogen plasma molecular beam epitaxy under gallium-rich conditions

Cubic GaN has been grown under gallium Ga -rich growth conditions using radio frequency nitrogen plasma molecular beam epitaxy on MgO 001 substrates. Reflection high energy electron diffraction patterns indicate the smoothness of the c-GaN surface and show 2 and even 8 periodicities after the growth at sample temperature Ts 200 °C and 1 1 at higher temperatures. Scanning tunneling microscopy images reveal a sequence of variant surface reconstructions including c 4 12 , 4 7, c 4 16 , 4 9, c 4 20 , and 4 11. These variant reconstructions correspond to slightly different Ga adatom coverages all less than 1/4 ML, with 4 11 having the highest, and c 4 12 the lowest Ga coverage. The electronic properties of these six variant reconstructions are investigated, and they are found to have a metallic nature. © 2006 American Institute of Physics. DOI: 10.1063/1.2356604