Recombination luminescence in aluminum nitride ceramics

Abstract

Photoluminescence (PL) and afterglow luminescence (AGL) produced by UV laser irradiation with varied intensity were studied in AlN ceramics in the 10–300 K temperature range. Luminescence spectra of AlN ceramics contain the UV–blue band built up of two components – the UV (3.18 eV) and Blue (2.58 eV) bands, which are presumably ascribed to recombination luminescence involving oxygen‐related centers in the bulk and on the surface of AlN, correspondingly. It was found that position of the emission band maximum of AlN ceramics depends on such factors as excitation density, temperature, and delay time after excitation ceasing – in the case of AGL. In PL spectra, the excitation density growth produces the blue shift of the UV emission band peak, and temperature growth from 10 to 300 K causes first the blue and then the red shift. The most characteristic feature of the AGL is the red shift of the resultant UV–blue peak occurring with growth of delay time after excitation ceasing. Explanations of these phenomena are proposed basing on properties of radiative donor–acceptor pair recombination in semiconductors and varied relative contribution of the UV and Blue components to build‐up of the resultant UV–blue band.