Capacitance properties of MOS capacitors with oxide-hosted Si nanoparticles

Abstract

In the present publication, we give an extended discussion to the previously proposed model invented to describe the humplike feature that was observed in the accumulation branch of low-frequency capacitance-voltage (C-V) characteristics of MOS capacitors with oxide-hosted Si nanoparticles (V.A. Stuchinsky <i>et al.</i>, Tech. Phys. Letters, 2012, Vol. 38, No. 9, pp. 845–848). In comparison with the above publication, the reasoning leading to this model and the basic properties of the model are outlined in greater detail. In a simple version, the model assumes monopolar injection of electrons or holes into the oxide layer from one of the two MOS contacts (with semiconductor or metal) and their subsequent migration along the linear chains formed by Si nanoparticles in the oxide with a certain spread of tunneling distances in individual chains. Manifestations of the variation of nanoparticle-accumulated charge at the ac frequency in the C-V characteristics of MOS capacitors were examined in computer-aided simulations performed for different arrangements of Si nanoparticles in nanoparticle chains and monopolar injection of holes from the accumulation layer of <i>p</i>-type semiconductor. Discussing most favorable conditions for organization of efficient electroluminescence in film systems with Si nanoparticles, we give qualitative consideration to a more complex case with bipolar injection of charge carriers into the oxide layer from both contacts. Next, we put forward a hypothesis that the capacitance peaks that in some cases were observed in MOS capacitors in strong inversion could be a manifestation of the same hump-feature formation mechanism.