Atomic scale morphology of thin GaNAs films: Effects of nitrogen content and growth temperature

摘要

The surface morphology of 8 nm GaNAs layers grown by molecular-beam epitaxy on GaAs(001) substrates has been studied as a function of nitrogen content and growth temperature using scanning tunneling microscopy (STM). Increasing the nitrogen content from 0%-3% leads to a pronounced increase in surface roughness, caused by the appearance of deep pits. Raising the growth temperature from 400-500℃ produces the same effect. We propose that pit formation is symptomatic of phase segregation. STM images show that the GaNAs layers adopt an (n X 3) surface reconstruction, suggesting that a disproportionately high concentration of N is present on the postgrowth surface compared with that incorporated into the layer during growth.