Year: 2014
Type: article
Abstract: We study the surface conductivity of a field-effect transistor (FET) made of a periodic array of spherical semiconductor nanocrystals (NCs). We show that electrons introduced to NCs by the gate voltage occupy one or two layers of the array. Computer simulations and analytical theory are used to study the array screening and corresponding evolution of electron concentrations of the first and second layers with growing gate voltage. When first-layer NCs have two electrons per NC the quantization energy gap between its $1s$ and $1p$ levels induces occupation of $1s$ levels of second-layer NCs. Only at a larger gate voltage electrons start leaving $1s$ levels of second-layer NCs and filling $1p$ levels of first-layer NCs. At substantially larger gate voltage, all electrons vacate the second layer and move to $1p$ levels of first-layer NCs. As a result of this nontrivial evolution of the two layers' concentrations, the surface conductivity of the FET nonmonotonically depends on the gate voltage. The same evolution of electron concentrations leads to nonmonotonic behavior of the differential capacitance.
Source: Physical Review B
Authors: K. V. Reich, Tianran Chen, B. I. Shklovskii
Institutions: University of Minnesota, Ioffe Institute
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2060046845