Investigating the gas sensing properties of semiconductors modified with femtosecond laser irradiation and approaches to minimize the humidity interference on sensing measurements

• Grant number: 24/08759-0
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: January 01, 2025
• End date: December 31, 2025
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Nonmetallic Materials
• Principal Investigator: Elson Longo da Silva
• Grantee: Pedro Paulo da Silva Ortega
• Supervisor: Cesare Malagu'
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Institution abroad: Università degli Studi di Ferrara, Italy
• Associated to the scholarship: 23/07486-8 - Surface modification of nanostructured semiconductors via irradiation with femtosecond laser and electron beam aiming gas sensor applications, BP.PD

Abstract

This proposal is divided in two complementary topics: the effects of femtosecond laser irradiation on the gas sensing properties of n- and p-type semiconductors, and heterostructures as a tool to minimize the interference of humidity on the sensing properties of chemoresistive gas sensors. Both femtosecond laser-modified nanostructures and heterostructures with different morphologies were prepared in the ongoing post-doctorate project (FAPESP 2023/07486-8). This samples will be used to prepare thick films (via the screen-printing technique) in which the electrical characterizations will be performed. The influence of the different atmospheres on the defect structure and electrical properties of femtosecond laser irradiated ZnO, NiO, and CeO2 samples will be investigated. Also, heterostructures composed of the abovementioned semiconductors with different morphologies with NiO, reduced graphene oxide (RGO), and MoS2 will be investigated. Also, other possible heterostructures will eventually be studied. The samples will be characterized under oxidative and reducing atmospheres, such as O2, CO, H2, VOCs, among others, and the influence of humidity on the performance of the sensors will be assessed by controlling the relative humidity percentage inside the test chamber during the experiments. Complex Impedance Spectroscopy (CIS) and the gas-sensing measurements will be used to obtain information about the sensitivity, selectivity, and working temperature of the thick films as well as the defect structure. The experimental results will be discussed in terms of the morphology, heterojunctions, structural modifications generated by irradiation, and semiconductor type, shedding light on the basic conduction mechanisms responsible for the gas detection.