Abstract
High-quality AlN epitaxial films have been grown on Si substrates by pulsed laser deposition (PLD) by effective control of the interfacial reactions between AlN films and Si substrates. The surface morphology, crystalline quality and interfacial property of as-grown AlN/Si hetero-interfaces obtained by PLD have been systemically studied. It is found that the amorphous SiAlN interfacial layer is formed during high temperature growth, which is ascribed to the serious interfacial reactions between Si atoms diffused from the substrates and the AlN plasmas produced by the pulsed laser when ablating the AlN target during the high temperature growth. On the contrary, abrupt and sharp AlN/Si hetero-interfaces can be achieved by effectively controlling the interfacial reactions at suitable growth temperature. The mechanisms for the evolution of interfacial layer from the amorphous SiAlN layer to the abrupt and sharp AlN/Si hetero-interfaces by PLD are hence proposed. This work of obtaining the abrupt interfaces and the flat surfaces for AlN films grown by PLD is of paramount importance for the application of high-quality AlN-based devices on Si substrates.
Highlights
We report on the epitaxial growth of high-quality aluminum nitride (AlN) films on Si(111) substrates by pulsed laser deposition (PLD) through controlling the interfacial reactions between AlN films and Si substrates, and systematical study on the revolution of AlN/Si hetero-interfaces from amorphous to sharp and abrupt interface, as well as their corresponding mechanisms
The as-grown AlN epitaxial films are studied by in-situ reflection high energy electron diffraction (RHEED), high-resolution X-ray diffraction (HRXRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and high-resolution transmission electron microscopy (HRTEM) for structural property and surface morphology
The RHEED patterns for ~6 nm-thick AlN films grown at 750 °C are slightly clearer than those of ~6 nm-thick AlN films grown at 700 °C
Summary
We report on the epitaxial growth of high-quality AlN films on Si(111) substrates by PLD through controlling the interfacial reactions between AlN films and Si substrates, and systematical study on the revolution of AlN/Si hetero-interfaces from amorphous to sharp and abrupt interface, as well as their corresponding mechanisms. As the growth temperature of AlN films is further decreased to 700 °C, the surface morphology of as-grown ~300 nm-thick AlN films becomes poorer with several big islands and the RMS surface roughness of these as-grown films is measured to be 2.5 nm, Figs.
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