Pressure-induced reversal of self-driven photocurrent polarity via P-N conduction switching in BiI3
image: The sample is subjected to global illumination under a xenon lamp, with a 5 V bias applied. Throughout the entire testing process, the photocurrent consistently exhibits a positive response. Due to variations in crystal structures, the photoresponse characteristics of the two phases of BiI3 exhibit inverse regulation under high pressure。 At 31.0 GPa, the photocurrent of BiI3 increased by more than three orders of magnitude compared to the initial value.
Credit: ©Science China Press
This study is led by Dr. Quanjun Li, Dr. Lijun Zhang and Dr. Bingbing Liu (Institute of State Key Laboratory of Superhard Materials, Jilin University). The research team reports dramatic reversible p−n switching during the semiconductor-to-semiconductor phase transition in BiI₃ under high pressure, accompanied by a substantial enhancement in photoelectric properties. Our ability to master semiconductor technology depends on controlling the type and density of electrical carriers to design optimized devices. Achieving a comprehensive understanding and precise control of carrier transport behavior profoundly influences the stability and power efficiency of forthcoming large-scale integrated circuits. However, achieving switchable and reversible control of polarity within a single material to design optimized devices remains a significant challenge.
The research team leverages the application of pressure, a technique previously instrumental in uncovering novel physical properties such as spin-crossover, piezochromism, and metallization, to induce conduction type switching in semiconductors. Unlike most pressure-induced switches that occur during semiconductor-to-metal transitions and thus limit broader application, the research team achieves p−n switching through semiconductor-semiconductor phase transitions under high pressure, maintaining the semiconductor state, which is crucial for applications such as photodetection. Additionally, previous work typically attributed negative photoconductivity at high pressure to carrier type switching; however, applying bias voltage during photocurrent measurements can mislead the determination of carrier type. The team propose that the carrier type of a material under high pressure can be determined by the polarity of the self-driven photocurrent, primarily governed by the photothermoelectric (PTE) effect. The polarity of this photocurrent, driven by spontaneous carrier movement due to concentration gradients under non-uniform illumination, excludes the influence of bias voltage. Accompanying the p−n transition, a reversal between positive and negative photocurrents was observed in BiI3, providing a feasible method to determine the conduction type of materials via photoelectric measurements. These findings not only deepen the understanding of carrier behavior in semiconductors but also provide valuable insights for the design of logic circuits and the optimization of device performance.
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See the article:
Dramatic switchable polarities in conduction type and self-driven photocurrent of BiI3 via pressure engineering
https://doi.org/10.1093/nsr/nwae419