Persistent Photoconductivity of Metal Oxide Semiconductors

Abstract

Photonic devices, in comparison to their conventional electronic counterparts, are gaining prominence as essential constituents of an increasing array of devices and applications. This is primarily attributed to their adjustable electronic characteristics, multifunctionality, and lower energy consumption. Particularly, persistent photoconductivity (PPC), characterized by the sustained presence of photoexcitation effects beyond the immediate termination of incident light, has garnered considerable attention within the realm of photonic devices. Because comprehending and modulating the electronic attributes of semiconductors hold paramount importance for their practical applications, in this Review, we place special emphasis on elucidating the PPC effects exhibited by various metal oxide semiconductors (MOSs) and their underlying mechanisms of origin. Furthermore, it is noteworthy that, for a substantial duration, investigations on PPC were primarily confined to the theoretical domain, with neglect of its practical applications, due to its detrimental impact on the sensitivity of photodetectors. However, in recent years, researchers have embarked on exploring an array of potential applications associated with PPC, encompassing areas such as optoelectronic synapses, optical memory, and charge storage. So, we summarize the diverse applications of MOSs in the context of PPC, offering insights into the prospects for advancing research on the PPC effects of MOSs.

Harnessing Persistent Photocurrent in a 2D Semiconductor–Polymer Hybrid Structure: Electron Trapping and Fermi Level Modulation for Optoelectronic Memory

“…Optoelectronic memory requires a persistent photocurrent (PPC) phenomenon that captures the photogenerated charge to maintain conductivity even when the light is turned off . Because 2D semiconductors are atomically thin, their optical characteristics can be modulated by environmental influences such as atmospheric conditions and substrate effects.…”

Investigation of the transient photo-response and switching window of an Al/indigo/Al device: unveiling negative photoconductivity and the photo-enhanced memory window

“…In general, these two effects can be considered to be persistent photoconductivity, wherein the photoconductivity persists for a long time even after the optical excitation is switched off. 8,9 Photo-conductivity has been observed in many materials, importantly in materials such as ZnO, GaN, GaN nanowires, 2H-MoSe 2 , MoS 2 , p-type Si nano-membranes, n-type GaN thin films, graphene, inorganic perovskites, etc. 10–19 While most of the literature studies discuss the positive photoconductivity, where the photocurrent increases as soon as the materials are exposed to given radiation, there are reports on materials that show switching between PPC and NPC depending on the excitation wavelength, 20 adsorption of oxygen 17,21,22 and temperature.…”