Electrical Performance Enhancement of CVD-Grown Undoped Tin Oxide (SNO2) Thin Films through Substrate Temperature Variation

Abstract

Undoped tin oxide (SnO₂) thin films deposited by chemical vapor deposition (CVD) were investigated at substrate temperatures from 310 °C to 400 °C. Four-point probe measurements revealed a significant reduction in resistivity from 1840 Ωcm at 310 °C to 3.13×10⁻⁴ Ωcm at 390 °C, while the sheet resistance decreased from 9.2×10⁷ to 15.68 Ω/square. The optimal electrical performance at 390 ^oC with conductivity (σ) of 3.19×10³ (Ωcm)^-1 surpasses many reported values for undoped SnO₂, and this value approaches industrially relevant transparent conducting oxide standards. The conductivity enhancement is attributed to increased carrier concentration and mobility due to improved crystallinity and oxygen vacancy formation at high substrate temperatures. Hence, the results revealed that substrate temperature is an important parameter for modifying the electrical performance of undoped SnO₂ thin films suitable for transparent electrode applications in photovoltaics and flat-panel displays.