Synthesis of PSi-n/CuO-p/Cu2O-n heterostructure for CO2 gas sensing at room temperature

In this work, n+-PSi/p-CuO/n-Cu2O bilayered heterostructure has been fabricated and tested against CO2 gas. p-type cupric oxide CuO was fabricated by a two-step thermal evaporation/oxidation process of copper (Cu) thin films. Subsequently, the n-type cuprous oxide Cu2O was deposited by electrochemical method on the top of the CuO/porous silicon (PSi) structure in an aqueous acetate bath [copper acetate (C4H6CuO4) and sodium acetate (C2H3NaO2)]. The current–voltage (I–V) and response time (I–t) characteristics of the heterostructure device to CO2 gas environment were studied. We have demonstrated that the bilayered PSi/CuO/Cu2O structure is sensitive to CO2 gas with a high sensitivity of the order of 80% at low bias potential (0.85 V) and fast response time of the order of 1 s at room temperature. Finally, a CO2 gas sensing mechanism has been proposed.