Capacitance spectroscopy of structures with Si nanoparticles deposited onto crystalline silicon p-Si

摘要

Capacitance spectroscopy has been used to study close-packed amorphous silicon nanoparticle layers (100 nm) deposited on p-type crystalline silicon by the laser electrodispersion method. It was found that this structure is an Au-nano-Si-p-S ip-n heterojunction that exhibit rectifying properties. In addition, a plateau was observed in its capacitance-voltage (C-V) characteristics, which indicates that the structure has a layer with spatially localized carriers. The thickness of this layer coincides with that of the deposited layer of amorphous nanoparticles. It was found by using deep level transient spectroscopy (DLTS) to examine the carrier emission from deep traps that position and amplitudes of the DLTS peaks E1 and E3, associated with localized states, synchronously vary both with the pulse voltages U-b and filling pulse voltages U-f when illuminated with white light. These dependences a due, respectively, (1) to an increase in the population of localized states upon a change in the position of the Fermi level because of the recharging of deep defects, (2) to the Coulomb interaction of carriers localized in the deep E3 and E1 states of the nano-Si layer and in the ionized surface states of Si nanoparticles, and (3) to the Stark effect. All the above specific features of the object under study are properties of quantum-dots (QDs) in which E3 and E1 are the ground and excited states of these QDs, respectively. Finally, it was observed that levels associated with the s- and p-states have too small capture cross sections that are not characteristic of QDs. It was suggested that the significant decrease in these values may be due to the hopping conduction mechanism.