Trap characterization of high-growth-rate laser-assisted MOCVD GaN

A detailed study comparing defect incorporation between laser-assisted metal-organic chemical vapor deposition (MOCVD)-grown GaN and conventional low- and high-growth-rate MOCVD GaN was conducted. Using deep-level transient and optical spectroscopy, traps throughout the bandgap were characterized where traps were found at E-C-0.25 eV, E-C-0.57 eV, E-C-0.72 eV, E-C-0.9 eV, E-C-1.35 eV, E-C-2.6 eV, and E-C-3.28 eV in all three samples. This indicates no new traps were observed in the laser-assisted MOCVD GaN sample. Overall, the trap concentrations in the laser-assisted MOCVD sample were similar to 2x higher than the optimal low-growth-rate sample, but this is primarily due to the increase in gallium vacancy E-C-2.6 eV and carbon-related E-C-3.28 eV trap concentrations. The E-C-0.9 eV trap concentration was similar to 2x higher in the laser-assisted sample, so proton irradiation experiments were conducted to identify the physical source of this level. The results indicated this was a native point defect likely related to gallium interstitials. Overall, this study shows that the laser-assisted MOCVD growth method is promising for future thick, high-quality GaN epilayers after further growth optimizations.

Automated summary

This study compares defect incorporation in laser-assisted MOCVD-grown GaN with conventional MOCVD GaN. No new traps were observed in the laser-assisted sample, and trap concentrations were similar to the optimal low-growth-rate sample. The increase in trap concentrations in the laser-assisted sample is primarily due to gallium vacancy and carbon-related traps.