Investigation of carbon incorporation in laser-assisted MOCVD of GaN

Background carbon (C) impurity incorporation in metalorganic chemical vapor deposition (MOCVD) grown gallium nitride (GaN) represents one of the major issues in further improving GaN vertical power device performance. This work presents a laser-assisted MOCVD (LA-MOCVD) technique to address the high-C issue in MOCVD homoepitaxial GaN under different growth rate (R-g) regimes and studies the correlations between [C] and R-g. [C] in LA-MOCVD GaN is reduced by 50%-90% as compared to the conventional MOCVD GaN for a wide growth rate range between 1 and 16 mu m/h. A mass-transport based model is developed to understand the C incorporation at different R-g regimes. The results obtained from the developed model are in good agreement with experimental data. The model further reveals that LA-MOCVD effectively suppresses C incorporation by reducing the active C species in the gas phase. Moreover, high step velocity in step flow growth mode can facilitate C incorporation at fast R-g, exhibiting steeper C increase. The theoretical model indicates that [C] can be suppressed below 10(16) cm(-3) with a fast growth rate (R-g) of 10 mu m/h by utilizing higher power LA-MOCVD and freestanding GaN substrates with larger off-cut angles.

Automated summary

This study demonstrates the reduction of carbon impurities in metalorganic chemical vapor deposition (MOCVD) grown gallium nitride (GaN) using laser-assisted MOCVD (LA-MOCVD) technique. The incorporation of carbon is effectively suppressed in LA-MOCVD under different growth rate regimes. A theoretical model explains the mechanism of carbon incorporation and suggests that higher power LA-MOCVD and freestanding GaN substrates with larger off-cut angles can further reduce carbon impurity levels.