Conductance fluctuations in amorphous silicon nanoparticles

Hydrogenated amorphous silicon nanoparticles with an average diameter of 150 nm have been synthesized by high-density plasma chemical vapor deposition. The particles are deposited onto a conducting substrate and are then surrounded by an insulating matrix, electrically isolating the particles. Electrical contact is made to the top of each nanoparticle; the current-voltage characteristics of the nanoparticles indicate that transport is space-charge limited through the a-Si:H. The spectral density of the current fluctuations in the a-Si:H nanoparticles is well described by a 1/f frequency dependence for frequency f. However, the octave separation dependence of the correlation coefficients of the noise power for the nanoparticles are very well described by an ensemble of fluctuators whose amplitudes are independently modulated in parallel, rather than the serial kinetics typically observed in bulk a-Si:H.