Deposition Mechanism and Characterization of Plasma-Enhanced Atomic Layer-Deposited SnOx Films at Different Substrate Temperatures

The promising functional tin oxide (SnOx) has attracted tremendous attention due to its transparent and conductive properties. The stoichiometric composition of SnOx can be described as common n-type SnO2 and p-type Sn3O4. In this study, the functional SnOx films were prepared successfully by plasma-enhanced atomic layer deposition (PEALD) at different substrate temperatures from 100 to 400 degrees C. The experimental results involving optical, structural, chemical, and electrical properties and morphologies are discussed. The SnO2 and oxygen-deficient Sn3O4 phases coexisting in PEALD SnOx films were found. The PEALD SnOx films are composed of intrinsic oxygen vacancies with O-Sn4+ bonds and then transformed into a crystalline SnO2 phase with increased substrate temperature, revealing a direct 3.5-4.0 eV band gap and 1.9-2.1 refractive index. Lower (<150 degrees C) and higher (>300 degrees 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 SnOx films near an estimated 1.74 suggests the highest mobility of 12.89 cm(2) V-1 s(-1) at 300 degrees C.

Automated summary

This study successfully prepared functional SnOx films with specific chemical compositions and found coexisting SnO2 and Sn3O4 phases in PEALD SnOx films. With increasing substrate temperature, the film transitioned from an amorphous to a crystalline SnO2 phase, exhibiting higher mobility.