Inhomogeneous broadening in Al-rich AlGaN/AlN single quantum wells
Abstract
Although high-quality AlₓGa₁₋ₓN/AlN quantum wells (QWs) have already been obtained, their photoluminescence (PL) spectra are still broad due to several factors including alloy broadening, intra-well fluctuations in well-width and alloy compositions, and inter-well variations. To eliminate inter-well variations, AlGaN/AlN single QWs (SQWs) were fabricated. Upon investigating their microscopic optical properties, the SQWs still exhibited broad PL, indicating that the remaining factors play an important role in determining the emission linewidth. Cathodoluminescence showed that microscopic compositional fluctuations within the well cause peak position shift of 3 nm (~96 meV), suggesting that they are the major contributing factor to the broad linewidth.