Resonant Raman scattering on self-assembled GaN quantum dots

Self-assembled GaN quantum dots grown on Al_0.15Ga_0.85N using Si as antisurfactant have been investigated by resonant Raman scattering. Phonons of GaN quantum dots of different sizes and the Al_0.15Ga_0.85N barrier layer were probed selectively by varying the laser excitation energy from 3.53 to 5.08 eV. Phonon confinement effects were studied on GaN quantum dots of 2-3 nm height. We show that although grown using Si (a common donor for GaN) as an antisurfactant, only a small electron concentration is present in the GaN quantum dots. Implications on the role of Si for the formation of the GaN quantum dots will be discussed.