SCANNING-TUNNELING-MICROSCOPY OF THE GAN(000(1)OVER-BAR) SURFACE

In-situ scanning tunneling microscopy studies have been performed on t he GaN(000 (1) over bar) surface. Four dominant reconstructions have b een observed: 1 x 1, 3 x 3, 6 x 6, and c(6 x 12). The I x 1 structure is formed by annealing the as-grown GaN surface to desorb excess Ga at oms. The higher-order reconstructions are formed by depositing submono layer quantities of Ga atoms onto this 1 x 1 surface. STM images showi ng the details of the reconstructions are presented and results of qua ntitative measurements of the number of Ga atoms required to form the various reconstructions are reported. Structural models are compared w ith the STM data. Reversible order/disorder phase transitions and adat om motion on the GaN surface are discussed.