Carcinogenic Heavy Metals Detection Based on ZnO Nanoribbons

Abstract

The theoretical investigation of zigzag ZnONRs for the detection of carcinogenic heavy metal atoms is reported in the current manuscript. The sensing characteristics of the ZnONRs towards toxic heavy metal atoms are examined by deploying the density functional theory (DFT) calculations together with non-equilibrium Green’s function (NEGF). The variation in the structural, electronic, and transport properties of the ZnONRs post passivation with heavy metal atoms at the edges are considered for the detection. Pristine ZnONR is a semiconductor with an energy bandgap of 0.49 eV and the ZnONRs become metallic after exposure to heavy metal atoms. The quantum transport calculations reveal the enhanced current conductivity in the heavy metal atom exposed ZnONR devices relative to the pristine ZnONR due to the induced metallicity. The local device density of states (LDOS) calculations reveal the major transmission of the carriers occurs through the edges. The ZnONR devices are highly sensitive to Sb and As as compared to the Pb atom. The ZnONR exhibit the highest sensitivity towards the Sb atoms with the sensor response around 3.57 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times \,\,{10}^{{7}}$ </tex-math></inline-formula> %. The sensor sensitivity towards the As and Pb is slightly lower with the sensor responses measured to be 3.52 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times \,\,10^{{7}}$ </tex-math></inline-formula> % and 2.86 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times \,\,10^{{7}}$ </tex-math></inline-formula> %, respectively. Further, FET devices exhibit high sensitivity at zero gate bias voltage of the order of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{{10}}$ </tex-math></inline-formula> for Sb-ZnO-Sb, As-ZnO-As, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{{9}}$ </tex-math></inline-formula> for Pb-ZnO-Pb devices. The obtained findings suggest that ZnONRs can effectively be used for the detection of carcinogenic heavy metal atoms.