Gas-phase nanoparticle formation during AlGaN metalorganic vapor phase epitaxy

Using in situ laser light scattering, we have directly observed the formation of gas-phase nanoparticles during AlN, GaN, and AlGaN metalorganic vapor phase epitaxy. The nanoparticles are sharply distributed in height 6 mm from the surface, in good agreement with a model based on a balance between thermophoretic and convective forces. By measuring the angular dependence of the scattering intensity, we determined that the AlN particle sizes were 35–50 nm, and particle densities were 1–6×108 cm−3, which corresponds to 20%–80% of the input Al being converted into nanoparticles.