Anomalous diode behavior of Cu2S/SnO2 p-n junction

Author(s)

Lima, Joao V. M. ^[1] ; Santos, Stevan B. O. ^[1] ; Silva, Rafael A. ^[1] ; Boratto, Miguel H. ^{[2, 1]} ; Graeff, Carlos F. O. ^{[2, 1]} ; Scalvi, Luis V. A. ^{[2, 1]}

Affiliation

^[1] Sao Paulo State Univ UNESP, Sch Sci, POSMAT Post Grad Program Mat Sci & Technol, BR-17033360 Bauru, SP - Brazil

^[2] Sao Paulo State Univ Unesp, Sch Sci, Dept Phys, BR-17033360 Bauru, SP - Brazil

• Document type: Journal article
• Source: JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS; v. 32, n. 16 JUL 2021.
• Web of Science Citations: 0

Abstract

Cu-doped SnO2 thin films present application as a gas sensor in H2S atmosphere, since the conductivity of SnO2 is increased due to the transformation of Cu into Cu2-xS. Based on this mechanism, a p-n Cu2S/SnO2 heterojunction is proposed and the electrical transport of this device is investigated. SnO2 thin films were obtained from the sol-gel by dip-coating technique, while Cu2S films were obtained from resistive evaporation. The formation of materials with low crystallinity and high disorder was analyzed by X-ray diffractograms and confirmed using optical absorption (Urbach's energy.) The bandgaps of the materials were estimated from the Tauc plot to be 3.7 +/- 0.1 eV for SnO2 and 2.5 +/- 0.1 eV for Cu2S. Impedance spectroscopy measurements show an accumulation of charges in the material, which possibly occurs in the depletion layer region. In addition, it shows a charge release that can be associated with the leakage current in the device. I x V measurements show a surprising behavior, opposite to that expected for a diode, with the device conducting only under reverse bias. A model has been proposed to explain this effect considering minority charge transport and interfacial barriers formed between the materials. (AU)

• FAPESP's process: 18/25241-4 - Investigation of structural, electrical and optical properties of the hybrid structure PbxSn1-xO2/TiO2: interface analysis and influence of substrate temperature
• Grantee: Stevan Brayan Oliveira dos Santos
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 18/26039-4 - Investigation of the semiconductor oxide SnO2, in the form of thin films, and combination with Cu2-xS forming multilayered heterostructures
• Grantee: João Victor Morais Lima
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 17/20809-0 - Study of organic devices for application in bioelectronics
• Grantee: Miguel Henrique Boratto
• Support Opportunities: Scholarships in Brazil - Post-Doctoral