Aluminum doping of zinc oxide thin films produced by atomic layer deposition for transparent conductors

• Autor(a) principal: Felizardo, Rui Pedro Martins
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/143767
• topic: TCO; ALD; ZnO; AZO; bulk resistivity; Hall mobility; Domínio/Área Científica::Engenharia e Tecnologia::Nanotecnologia

Transparent conducting oxides (TCOs) serve as a technological necessity in a multitude of indus-tries, being used in a vast array of devices, from photovoltaic cells to transparent electronics. However, high economical costs and growing environmental concerns have led to the decline in popularity of many key materials that are able to produce TCOs. This has, understandably, led to the research and development of new materials and technologies that are able to be produce TCOs in a cost-effective/en-vironmentally-friendly fashion, while still retaining the desired electrical properties. In the present work, atomic layer deposition (ALD) was employed in order to produce conformal and uniform zinc oxide (ZnO) and aluminum-doped zinc oxide (AZO) thin films. The deposition process of ZnO was optimized within a range of temperatures between 100-200 ºC, with a typical ALD regime being achieved within the interval 125-150 ºC, after the tuning of precursor pulses times. After the aforementioned optimization, AZO films were produced at a temperature of 150 ºC, of which the morphological and electrical properties were investigated as a function of dopant concentra-tion. Promising results were achieved, with an aluminum concentration of 1.98% attaining bulk resis-tivity and Hall mobility of 6.65x10-3 Ω*cm and 7.06 cm2/V*s, respectively. This opens the possibility to produce conformal and uniform films capable of attaining good electrical properties while employing a smaller thermal budget, facilitating film depositions on top of more temperature sensitive substrates.