Growth and characterization of tin oxide thin films and fabrication of transparent p-SnO/n-ZnO p–n hetero junction

• Growth of p-type semiconducting SnO thin films by rf sputtering.
• Varying the type of charge carriers with oxygen partial pressure.
• Atomic percentage of SnOx thin films from the XPS analysis.
• Demonstration of transparent p–n hetero junctions fabricated in the structure glass/ITO/n-ZnO/p-SnO.

p-Type and n-type tin oxide thin films were deposited by rf-magnetron sputtering of metal tin target by varying the oxygen pressure. Chemical composition of SnO thin film according to the intensity of the XPS peak is about 48.85% and 51.15% for tin and oxygen respectively. Nearest neighbor distance of the atoms calculated from SAED patterns is 2.9 Åand 2.7 Åfor SnO and SnO2 respectively. The Raman scattering spectrum obtained from SnO thin films showed two peaks, one at 113 cm−1 and the other at 211 cm−1. Band gap of as-deposited SnOx thin films vary from 1.6 eV to 3.2 eV on varying the oxygen partial pressure from 3% to 30% which indicates the oxidization of metallic phase Sn to SnO and SnO2. p-Type conductivity of SnO thin films and n-type conductivity of SnO2 thin films were confirmed through Hall coefficient measurement. Transparent p–n hetero junction fabricated in the structure glass/ITO/n-ZnO/p-SnO shows rectification with forward to reverse current ratio as 12 at 4.5 V.