Observation of Near Band Edge Transition in Aluminum Nitride Thin Film Grown by MOCVD

ABSTRACTThe Cathodoluminescence (CL) measurements of undoped and carbon doped aluminum nitride (AlN) thin films near the band-edge region were performed at 300, 77 and 4.2 K, respectively. These films were grown on three different substrates: 6H-SiC, 4H-SiC and sapphire. A dominant peak was observed in undoped samples around 5.9 eV. This peak can be further resolved into three distinct peaks at 6.05, 5.85, and 5.69 eV for AlN on sapphire. The temperature dependence of the peak positions and line widths were investigated. These peaks are believed to be due to exciton recombination. Also, the absorption spectra of carbon doped AlN on sapphire were analyzed to study the Urbach tail parameters which play an important role in near band-edge transitions.