resumo
The perovskite-like oxide Bi2ZnTiO6 (BZT) combines a narrow band gap with significant ferroelectric polarization, key parameters for the development of next-generation photovoltaic devices. Nevertheless, BZT remains a relatively unexplored material due to its difficult synthesis. The present experimental work unfolds and optimizes the deposition of BZT phase thin films by rf-sputtering method on standard Pt(111)/TiO2/SiO2/Si(001) substrates. The series of thin films explores different deposition conditions: Substrate temperature (350 degrees-600 degrees C), RF power (50-80 W), exposure time (30-120 min), O-2:Ar ratio (25-50%) and thermal treatments (air-O-2). Thin films deposited between 350 and 475 degrees C are mainly amorphous. Above 490-550 degrees C the films show incipient crystallization. Depositions at temperatures above 600 degrees C and heat treatments resulted in partial recrystallization of spurious Bi- or Zn-rich oxides and aurivillius or pyrochlore-like phases. At 550 degrees C, the films are dominated by a polycrystalline BZT phase in P4mm tetragonal structure, and the increase of the O-2:Ar ratio contributes to improve the B-site order. Not least, no significant structural changes were observed after similar to 3 years ageing. Diffuse reflectance measurements show relatively narrow optical band gaps between 1.4-1.9 eV within expected values for this system. Piezo-force microscopy revealed domains contrast and hysteresis loops correlated with the quality of the film crystallized BZT phase.
palavras-chave
PEROVSKITE; PARAMETER
categoria
Materials Science; Physics
autores
Figueiras, FG; Fernandes, JRA; Silva, JPB; Alikin, DO; Lourenço, AC; Tavares, PB
nossos autores
Armando António Cardoso Dos Santos Lourenço
Professor Auxiliar
Denis Alikin
Investigador Auxiliar
Fábio Gabriel Nazário Figueiras
Bolseiro de pós-DoutoramentoProjectos
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
agradecimentos
This work was supported by national funds through the Portuguese Foundation for Science and Technology (FCT/MEC) and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement in the framework of the Strategic Funding Contracts: IFIMUP: Norte-070124-FEDER-000070; NECL: NORTE-01-0145-FEDER-022096 and UID/NAN/50024/2019; CICECO: UIDB/50011/2020 and UIDP/50011/2020; CFUMUP: UIDB/04650/2020; CQVR: UIDB/QUI/00616/2020; CERN/FIS-TEC/0003/2021.