Aluminium oxide passivation films by liquid phase deposition for TiO2 ultraviolet solid–liquid heterojunction photodetectors

Abstract In this study, an aluminum oxide passivation layer generated through liquid-phase deposition (LPD) was used to improve the properties of a TiO2 ultraviolet solid–liquid heterojunction photodetector. An aluminum oxide deposition solution was used to reduce the oxygen vacancies of TiO2. Moreover, the surface roughness and porosity of the TiO2 film improved after aluminum oxide deposition. An aluminum oxide passivation layer was deposited on a TiO2/indium-tin-oxide (ITO)/glass photodetector with the precursors of aluminum sulfate and sodium bicarbonate. The responsivity and turn-off time of the TiO2/ITO photodetector were 133 mA/W and 34.6 s, respectively. A dense and uniform film surface could be obtained after the aluminum oxide passivation layer was deposited on TiO2 to form an Al2O3–TiO2 composite film. After deposition, the responsivity and turn-off time improved to 208 mA/W and 27.3 s, respectively. Thus, the LPD passivation film is highly favorable for improving the properties of photodetectors.