Growth of GaNAs films with As2 source in atomic hydrogen-assisted molecular beam epitaxy

We have investigated the effect of using As2 source instead of a more commonly used As4 source on the crystalline quality of GaNxAs1−x thin films grown by atomic hydrogen-assisted molecular beam epitaxy. Improved structural and optical properties of GaNAs thin films were obtained by using As2 source. The nitrogen atoms were incorporated into GaAs at a more stable rate under As2 flux than As4 flux, and a two-dimensional nucleation growth mode was promoted for growth of GaNxAs1−x with As2 source. As a consequence, the surface roughness measured for a 500 nm-thick Ga0.008N0.992As sample grown with As2 flux was 1-2 monolayers, which was three times more smoother than that for As4 sample. The photoluminescense measurements showed an improved potential fluctuation of 78.1 meV and twice the intensity at room temperature for As2 sample.