GaN heteroepitaxy by remote plasma MOCVD: Real time monitoring by laser reflectance interferometry

Epitaxial growth of GaN is carried out by r.f. remote plasma metalorganic c hemical vapor deposition (RP-MOCVD) using trimethylgallium and N-2-H-2 plas mas as precursor of gallium and nitrogen, respectively. The RP-MOCVD leads to different growth kinetics and surface morphology depending on trimethylg allium and hydrogen fluxes. In situ laser reflectance interferometry (LRI) is used to monitor in real time the growth rate, the thickness, the surface roughness, rms, and the optical absorption of the GaN growing epilayers an d their dependence on growth parameters. In particular, a strong degradatio n of surface morphology and GaN faceting is observed when growth is carried out under nitrogen- and hydrogen-rich conditions. Moreover, depending on t he growth rate, the transition from a layer-by-layer (2D) growth to an isla nds (3D) growth can be discriminated by LRI. Reflectivity data are corrobor ated by AFM measurements.