Solution-Processed Metal Oxide Layers for Use in Infrared Photodetectors

• Autor(a) principal: Matos, Manuel António Gomes Filipe de
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/91294
• topic: infrared; SWIR; image sensor; quantum dots; photodiode; metal-oxide; Domínio/Área Científica::Engenharia e Tecnologia::Nanotecnologia

Short-wave infrared (SWIR) imaging has been a relevant field mostly in medical, military and surveillance applications. This comes from the possibility to acquire valuable information from materials and objects that is not accessible in the visible range. As a result, in the imaging field new technologies emerge to address the shortcomings of the standard well established technologies. Monolithic Thin-film Photodetectors (TFPD) is a technology that appears as an alternative to the standard ones. TFPD technology allows us to use colloidal quantum dots (QDs) as the photodiode active layer, a major aspect due to their bandgap tunability, replacing default expensive III-V semiconductors. Also, we are able to process and synthesize, via low cost techniques, metal oxide layers to use as transport layers. In this work, the optimization of a PbS QD-based photodiode stack was successfully performed, with focus on solution-processed metal oxide electron and hole transport layers. Photodiodes were fully processed and characterized. Optimization on glass substrates was firstly done and then transferred to silicon-based substrates. Glass substrate devices showed a 37% external quantum efficiency at 1450 nm wavelength and Si substrate devices above 20% for the same wavelength. A 200-nm thick photodiode stack was achieved, showing dark currents around 10-2 mA/cm2 at -3 V, for both glass and silicon substrate.