Giant piezoelectric effect in GaN self-assembled quantum dots
We observe in strained GaN self-assembled quantum dots grown on an AlN layer, a dramatic modification of the optical emission spectra as the dot size varies. In large quantum dots with an average height of 4.1nm, the photoluminescence (PL) peak is centered at 2.95eV, nearly 0.5eV below the bulk GaN bandgap. We attribute this enormous redshift to a giant 5.5MV cm?1 piezoelectric field present in our dots. Temperature-dependent PL studies reveal the strongly zero-dimensional character of this QD system and are consistent with an intrinsic PL mechanism.
giant piezoelectric effect gan quantum dots emission spectra