Exploring and controlling intrinsic defect formation in SnO2 thin films

Abstract

By investigating the influence of key growth variables on the measured structural and electrical properties of SnO ₂ prepared by pulsed laser deposition (PLD) we demonstrate fine control of intrinsic n-type defect formation.

By investigating the influence of key growth variables on the measured structural and electrical properties of SnO ₂ prepared by pulsed laser deposition (PLD) we demonstrate fine control of intrinsic n-type defect formation. Variation of growth temperatures shows oxygen vacancies (V _O) as the dominant defect which can be compensated for by thermal oxidation at temperatures >500 °C. As a consequence films with carrier concentrations in the range 10 ¹⁶–10 ¹⁹ cm ⁻³ can be prepared by adjusting temperature alone. By altering the background oxygen pressure ( P _D) we observe a change in the dominant defect – from tin interstitials (Sn _i) at low P _D (<50 mTorr) to V _O at higher P _D with similar ranges of carrier concentrations observed. Finally, we demonstrate the importance of controlling the composition target surface used for PLD by exposing a target to >100 000 laser pulses. Here carrier concentrations >1 × 10 ²⁰ cm ⁻³ are observed that are associated with high concentrations of Sn _i which cannot be completely compensated for by modifying the growth parameters.