An IR Spectroscopic Investigation of Nanostructured AlN and GaN Powder Surfaces

By combining the results of IR spectroscopy experiments, both in the transmission and diffuse reflectance modes, with data obtained by HRTEM, XRD and XPS an overall picture of AlN and GaN nanoparticle surface structures and functionality were deduced. The surface species from the IR data analysis indicated that the nanostructured AlN powder surfaces had acidic and weak basic sites in the form of Al³⁺ and Al₃N^–, respectively. Also present were -OH, -NH₂, and -NH. For GaN, the bulk core of the particle had a zincblendel (FCC) structure with nitrogen vacancies, and the only functionality detected was Ga–H. The surface of the particles had a wurtzite(HCP) structure, with abundant NH and NH₂ groups as well as OH and Ga³⁺ functionalities.