Tuning the electronic properties of ZnO and CuCrO2 though annealing for transparent electronic applications

• Autor(a) principal: Afonso, João Ricardo Antunes
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/25055
• topic: ZnO; CuCrO2; Annealing steps; Carrier Concentration; Transparent P-N Junctions; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia dos Materiais

Transparent microelectronics applications have been receiving a great amount of research because of the continuous demand for better products from the consumers due to their use in almost every product of the modern-day society. This work comes to explore two of the missing building blocks in completely transparent microelectronics, a capable transparent conductive oxide (TCO) that can substitute indium-tin-oxide (ITO) and a good transparent p-type TCO. The materials studied were ZnO and CuCrO2 that were tuned for a wide range of carrier concentration though changes in deposition parameters and annealing steps. ZnO thin films have shown a wide range of carrier concentration from 8∗1019 approaching 1018 −3 and even values above 1020 −3, in the case of Aluminium doped ZnO films. An important relationship was discovered during this work, a direct interplay of the mobility with the carrier concentration, ∝, that holds in the range between 1018− 3∗1019−3. CuCrO2 thin films have shown also a wide range of tunability in terms of carrier concentration from 2∗1021 to 1017 −3, showing a progressive increase of optical transmittance from 37% to 60% with the decrease in carrier concentration, which makes them more suitable for transparent electronics applications. A P-N junction was proposed with these materials with a projected type-II band alignment and optimized carrier concentration of about 5∗1018 −3 on both sides of the junction. The junction was patterned by etching and photolithography but unfortunately the carrier concentration was not the optimized one, that lead into a ohmic contact.