Spatio-time-resolved cathodoluminescence (STRCL), which uses a femtosecond-laser-driven pulsed photoelectron gun instead of the cw electron gun of spatially resolved cathodoluminescence (CL) combined with scanning electron microscopy (SEM), is introduced for probing local luminescence dynamics in quantum structures and nanostructures of wide-bandgap (WBG) semiconductors. As STRCL is based on SEM, multi-scale characterization of a structure with high spatial definition is possible, and the use of pulsed electron-beams allows the sub-picosecond excitation of any WBG semiconductor. By using our STRCL system, high-resolution near-band-edge CL imaging allowed the visualization of nonradiative recombination channels in a low dislocation density GaN substrate: the local CL decay curves of the sample at 300 K showed a nearly single-exponential lineshape, and the lifetimes were sensitively position-dependent. Free- and bound-exciton recombination dynamics with the energy transfer processes in GaN, AlN, and hexagonal BN, as well as local emission dynamics in Al0.68Ga0.32N quantum wells, were successfully investigated in the UV to deep UV wavelengths down to 200 nm.
ASJC Scopus subject areas
- Physics and Astronomy(all)