Porous Silicon Gas Sensors: The Role of the Layer Thickness and the Silicon Conductivity. - Francisco Ramírez-González; Godofredo García Salgado; Enrique Rosendo; Tomás Díaz; Fabiola Nieto-Caballero; Antonio Coyopol; Román Romano; Alberto Luna 001; Karim Monfil; Erick Gastellou (Sensors, 2020)