Semiconducting metamorphism and dielectric characteristics of tetragonal Mn-doped SnO₂ nanocrystals

Abstract The present report represents, the physicochemical characteristics of pure and Mn-substituted SnO 2 nanocrystals (NCs) [Sn (1-x) Mn x O 2 NCs, where x = 0, 0.05, and 0.10], synthesized using the co-precipitation technique. Structural characterization revealed that all the compositions possessed tetragonal crystal phase with space group <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>P</mml:mi> <mml:msub> <mml:mrow> <mml:mn>4</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>/</mml:mo> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> <mml:mi mathvariant="italic">mnm</mml:mi> </mml:math> with no signature of impurities. Microstructural characterization depicted that the average grain size decreased from 34 nm to 22 nm with Mn doping in the host SnO 2 . The appearance of 643 cm −1 and 484 cm −1 is attributed to O-Sn-O and Sn-O vibrations, which confirmed the formation of Sn (1-x) Mn x O 2 NCs. The electrical characterizations were conducted using Hall effect measurements and it was observed that doping of Mn in the crystal framework of host SnO 2 decreases the carrier conce n tration ( n ) from 5.73 × 10 16 cm −3 to 3.36 × 10 16 cm −3 whereas the mobility (μ) decreases from 5.18 cm 2 Vs −1 to 2.35 cm 2 Vs −1 thereby transforming the system from n-type behavior of pristine SnO 2 to p-type with Mn doping. The dielectric constant also decreases with increasing Mn concentration in the system. I-V characteristics show linear behavior with improved resistance with the addition of Mn to SnO 2 .