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Two-dimensional transition metal dichalcogenide (TMDC) semiconductors are emerging as strong contenders for electronic devices that can be used in highly radioactive environments such as outer space where conventional silicon-based devices exhibit nonideal characteristics for such applications. To address the radiation-induced interface effects of TMDC-based electronic devices, we studied high-energy proton beam irradiation effects on the electrical properties of field-effect transistors (FETs) made with tungsten diselenide (WSe2) channels and hexagonal boron-nitride (hBN)/SiO2 gate dielectrics. The electrical characteristics of WSe2 FETs were measured before and after the irradiation at various proton beam doses of 1013, 1014, and 1015 cm−2. In particular, we demonstrated the dependence of proton irradiation-induced effects on hBN layer thickness in WSe2 FETs. We observed that the hBN layer reduces the WSe2/dielectric interface effect which would shift the transfer curve of the FET toward the positive direction of the gate voltage. Also, this interface effect was significantly suppressed when a thicker hBN layer was used. This phenomenon can be explained by the fact that the physical separation of the WSe2 channel and SiO2 dielectric by the hBN interlayer prevents the interface effects originating from the irradiation-induced positive trapped charges in SiO2 reaching the interface. This work will help improve our understanding of the interface effect of high-energy irradiation on TMDC-based nanoelectronic devices. [ABSTRACT FROM AUTHOR]

We investigated the effects of stoichiometry on photovoltages and photocurrents in CuBi2O4 thin-film photocathodes grown by pulsed laser deposition under different oxygen partial pressures to manipulate their stoichiometry. While the X-ray diffraction patterns show crystalline phases in the CuBi2O4 thin films, it is found that the Cu/Bi ratio of the CuBi2O4 thin films varied from ~0.3 to ~0.5 which are analyzed by X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. The slightly off-stoichiometric CuBi2O4 thin-film photocathode with a Cu/Bi ratio of ~0.44 shows the highest photocurrent density in the CuBi2O4 thin films. More interestingly, the off-stoichiometric CuBi2O4 thin-film photocathode with a Cu/Bi ratio of ~0.44 exhibited a stable open-circuit voltage difference of ~0.2 V RHE without severe degradation over time. On the other hand, the photovoltage of the stoichiometric CuBi2O4 thin-film photocathode with a Cu/Bi ratio of ~0.5 gradually decreased as a function of time. Our results suggest that stoichiometry manipulation can be one of the promising strategies to achieve long-term stable Cu-based oxide photocathodes with the maintenance of a stable photovoltage. [ABSTRACT FROM AUTHOR]

Two-dimensional transition metal dichalcogenide (TMDC) semiconductors are emerging as strong contenders for electronic devices that can be used in highly radioactive environments such as outer space where conventional silicon-based devices exhibit nonideal characteristics for such applications. To address the radiation-induced interface effects of TMDC-based electronic devices, we studied high-energy proton beam irradiation effects on the electrical properties of field-effect transistors (FETs) made with tungsten diselenide (WSe 2 ) channels and hexagonal boron-nitride (hBN)/SiO 2 gate dielectrics. The electrical characteristics of WSe 2 FETs were measured before and after the irradiation at various proton beam doses of 10 13 , 10 14 , and 10 15 cm -2 . In particular, we demonstrated the dependence of proton irradiation-induced effects on hBN layer thickness in WSe 2 FETs. We observed that the hBN layer reduces the WSe 2 /dielectric interface effect which would shift the transfer curve of the FET toward the positive direction of the gate voltage. Also, this interface effect was significantly suppressed when a thicker hBN layer was used. This phenomenon can be explained by the fact that the physical separation of the WSe 2 channel and SiO 2 dielectric by the hBN interlayer prevents the interface effects originating from the irradiation-induced positive trapped charges in SiO 2 reaching the interface. This work will help improve our understanding of the interface effect of high-energy irradiation on TMDC-based nanoelectronic devices., (© 2024 IOP Publishing Ltd.)