Deep-level defects related to the emissive pits in thick InGaN films on GaN template and bulk substrates

Abstract

We studied the emissive pits in InGaN films grown on compressive and strain-free GaN underlying layers. Pit density decreased with the full width at half maximum of ω(0002) of InGaN. The films grew on compressive and strain-free GaN underlying layers with spiral and step-flow modes, respectively. Carbon impurities accumulated inside the pits. Comparison of cathodoluminescence inside the pits and steady-state photocapacitance spectra showed that the energy level of the carbon impurities appeared at ∼2.8 eV below the conduction band (Ec) for both types of pits. Deep-level defects at Ec −2.4 eV resulting in green fluorescence emission were considered to originate from pits related to screw dislocations.