APL-comment

APPLIED PHYSICS LETTERS 86, 226101 s2005dComment on “Giant exciton-light coupling in ZnO quantum dots”†Appl. Phys. Lett. 81, 748 „2002…‡a!Vladimir A. Fonoberov and Alexander A. BalandinNano-Device Laboratory, Department of Electrical Engineering, University of California—Riverside,Riverside, California 92521sReceived 6 December 2004; accepted 4 May 2005; published online 26 May 2005dfDOI: 10.1063/1.1942632g1˛In a recent letter, Gill and Kavokin reported calculation R=l /2 « . The latter, as can be expected, indicates that the0 bof the radiative lifetime in ZnO quantum dots sQDsd, which exciton-light coupling reaches a maximum when the QD di-took into account the retardation effects. The main result of ameter is approximately equal the wavelength of light in thetheir work was that the radiative lifetime t reaches a mini-r QD material. This observation is in line with the calculations3mum of 264 ps for a ZnO QD with radius 16.7 nm. The of Takagahara for other material systems. Since both exci-authors have concluded that it is significantly smaller than ton w.f. s1d and s3d give almost the same maximum of thefor CdSe or InGaAs QDs and demonstrates “a huge coupling˛recombination rate, one can deduce that krl= 3R/p. Thus,of the electronic states with the electromagnetic field” in the minimum t should have been 264 ps/32=8.2 ps for therZnO QDs. 4˛QD radius of 16.7 nm323p/ 3=60 nm.The accurate knowledge of the radiative lifetime in ZnOIn addition, there are ...