  We report measurements of low-frequency electronic noise in ordered
superlattice, weakly-ordered and random-packed thin films of 6.5 nm PbSe
quantum dots prepared using several different ligand chemistries. For all
samples, the normalized noise spectral density of the dark current revealed a
Lorentzian component, reminiscent of the generation-recombination noise,
superimposed on the 1/f background (f is the frequency). An activation energy
of 0.3 eV was extracted from the temperature dependence of the noise spectra.
The noise level in the ordered films was lower than that in the weakly-ordered
and random-packed films. A large variation in the magnitude of the noise
spectral density was also observed in samples with different ligand treatments.
The obtained results are important for application of colloidal quantum dot
films in photodetectors.
