Deep-level studies in GaN layers grown by epitaxial lateral overgrowth

The electrical properties, deep-level spectra, microcathodoluminescence (MCL) spectra and diffusion lengths of minority charge carriers were measured in GaN films grown by the epitaxial lateral overgrowth (ELOG) technique. The results are compared to the properties of GaN layers grown in a standard fashion without masking of the initial template. MCL and electron beam induced current (EBIC) imaging of the laterally overgrown regions revealed the presence of dark spots with density of 1–5 × 106 cm− 2 that are associated with individual dislocations. The concentration of deep electron and hole traps was found to be much higher in the standard material than in the ELOG material. Diffusion lengths of minority carriers determined from EBIC signal profiling gave values of 0.8–1 μm along the bright regions and 0.4–0.5 μm in the dark regions of the ELOG samples. Similar measurements on metal organic chemical vapor deposition templates gave a diffusion length of 0.4–0.5 μm, close to the diffusion length in the dark stripes of the ELOG samples.