Piezo-mechanical impedance of a nanosized CdS single crystal

Abstract

The design of a piezo-mechanical device based on a nanosized CdS single crystal is a challenging task for demonstrating both the technological capabilities of crystal growth control in order to form simple sensor device topologies and the integrated usage of unique material properties with a bottom-up approach. Analysis of luminescence spectra of CdS nanocrystals grown from the gas phase at a temperature of 400 °C in the quasi-closed volume revealed that doping takes place with tin, as a component of ITO conductive film, simultaneously with doping with gold or silver from catalyze droplets. Piezo-mechanical longitudinal vibrations along the main symmetry axis of wurtzite-type single crystal have been presented in the continuous medium approximation based on experimental values of the nanocrystal piezo-module. Theoretical analysis of the frequency dependence of resonance oscillations for the nanosized beam-type piezo-mechanical resonators based on the CdS nanocrystal enabled us to ascertain the equivalent RLC two-pole and values of the equivalent elements L and C prognosticated: there are high values of L, tens and hundreds of henry, and very small values of the series capacitance of the order of femto- and attofarads. Below the resonance, the impedance of the crystal reaches gigaohms and has an inductive character.