Deposition Mechanism and Characterization of Plasma-Enhanced Atomic Layer-Deposited SnO(x) Films at Different Substrate Temperatures

The promising functional tin oxide (SnO(x)) has attracted tremendous attention due to its transparent and conductive properties. The stoichiometric composition of SnO(x) can be described as common n-type SnO(2) and p-type Sn(3)O(4). In this study, the functional SnO(x) films were prepared successfully by plasma-enhanced atomic layer deposition (PEALD) at different substrate temperatures from 100 to 400 °C. The experimental results involving optical, structural, chemical, and electrical properties and morphologies are discussed. The SnO(2) and oxygen-deficient Sn(3)O(4) phases coexisting in PEALD SnO(x) films were found. The PEALD SnO(x) films are composed of intrinsic oxygen vacancies with O-Sn(4+) bonds and then transformed into a crystalline SnO(2) phase with increased substrate temperature, revealing a direct 3.5–4.0 eV band gap and 1.9–2.1 refractive index. Lower (<150 °C) and higher (>300 °C) substrate temperatures can cause precursor condensation and desorption, respectively, resulting in reduced film qualities. The proper composition ratio of O to Sn in PEALD SnO(x) films near an estimated 1.74 suggests the highest mobility of 12.89 cm(2) V(−1) s(−1) at 300 °C.