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

Abstract

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 14 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.