X-ray reflectivity and atomic force microscopy studies of MOCVD grown AI_xGa_(1-x)N/GaN superlattice structures

The grazing incidence X-ray reflectivity(GIXR) technique and atomic force microscopy(AFM) were exploited to obtain an accurate evaluation of the surfaces and interfaces for metalorganic chemical vapor deposition grown AlGaN/GaN superlattice structures.The X-ray diffraction results have been combined with reflectivity data to evaluate the layer thickness and Al mole fraction in the AlGaN layer.The presence of a smooth interface is responsible for the observation of intensity oscillation in GIXR,which is well correlated to step flow observation in AFM images of the surface.The structure with a low Al mole fraction(x = 0.25) and thin well width has a rather smooth surface for the R,of AFM data value is 0.45 nm.

The grazing incidence X-ray reflectivity（GIXR） technique and atomic force microscopy（AFM） were exploited to obtain an accurate evaluation of the surfaces and interfaces for metalorganic chemical vapor deposition grown AlxGa1-xN/GaN superlattice structures.The X-ray diffraction results have been combined with reflectivity data to evaluate the layer thickness and Al mole fraction in the AlGaN layer.The presence of a smooth interface is responsible for the observation of intensity oscillation in GIXR,which is well correlated to step flow observation in AFM images of the surface.The structure with a low Al mole fraction（x = 0.25） and thin well width has a rather smooth surface for the Rrms,of AFM data value is 0.45 nm.