AlN/GaN short-period superlattices with monolayer AlN for optical-device applications

Abstract

A series of AlN/GaN short-period superlattices with monolayer AlN were prepared by hot-wall epitaxy. The superlattice structure was confirmed by X-ray diffraction through a comparison between the measured diffraction curves and simulated ones, which indicates good controllability of the HWE technique. Interband photoluminescence (PL) and photoluminescence excitation (PLE) spectra were measured. Relatively strong PL emissions compared with conventional AlGaN/GaN superlattices were observed, which can be attributed to the small piezoelectric effect. A small Stokes shift should be noted, which may suggest small interface fluctuation in consistence with the XRD observation. The energy shifts of the band-edge emission with the GaN well thickness agree well with the calculated results within the envelope wave-function framework at least for the well thickness above 2 nm . Optical device applications such as light emitting devices in the ultraviolet and mid-infrared regions via interband and intersubband electron transitions are discussed.