Photocurrent generation in SnO2 thin film by surface charged chemisorption O ions

Self-Powered Photodetector Based on a Ag Nanoparticle-Decorated Gd2O3 Nanorod

“…This decrease in barrier height can be related to the oxygen chemisorption process. Studies have demonstrated that the chemisorption of oxygen molecules on the surface of semiconductors results in a space charge region, causing band bending. − Furthermore, chemisorbed oxygen from the surface of the semiconductor can be removed when exposed to light illumination, allowing the band bending to recover via the internal photoelectric effect . Under dark conditions, as shown in Figure a, due to the chemisorption process, oxygen molecules from the air react with the free electrons (e – ) from the Gd 2 O 3 surface to form negatively charged oxygen ions (O 2 – ) at the interface of Ag and Gd 2 O 3 , as explained by the equation O 2 + e – → O 2 – .…”

Experiment and Theoretical Calculation of the Surface Space Charge Region Effect on Photocurrent Generation of SnO2 Bilayer Photodiode Devices

“…The above‐mentioned built‐in electrical potential in the surface space charge region in the SnO 2 layer greatly depends on the oxygen vacancy concentration in the SnO 2 phase of the SnO 2 ‐based UV‐photodetectors. Lee et al's study also stated that a critical oxygen vacancy concentration in the SnO 2 phase of the UV‐photodetectors is required to create a sufficient built‐in electrical potential in the surface space charge region to generate the detectable photocurrent . So, they concluded that the critical electrical field required in the SnO 2 surface layer relies on the two criteria: 1) an adequate vacancy concentration in the SnO 2 layer, 2) oxygen ion‐adsorption on the SnO 2 surface by annealing SnO 2 photodiode device in the O 2 ambient at elevated temperature .…”

“…Lee et al's study also stated that a critical oxygen vacancy concentration in the SnO 2 phase of the UV‐photodetectors is required to create a sufficient built‐in electrical potential in the surface space charge region to generate the detectable photocurrent . So, they concluded that the critical electrical field required in the SnO 2 surface layer relies on the two criteria: 1) an adequate vacancy concentration in the SnO 2 layer, 2) oxygen ion‐adsorption on the SnO 2 surface by annealing SnO 2 photodiode device in the O 2 ambient at elevated temperature . However, for SnO 2 ‐based UV‐photodiodes, the oxygen vacancies in the SnO 2 phase (causing low mobility) would trap the photocarriers and greatly reduce the lifetime of the generated photocarriers.…”