Ultraviolet (UV) radiation has a variety of impacts including the health of humans, the production of crops, and the lifetime of buildings. Based on the photovoltaic effect, self-powered UV photodetectors can measure and monitor UV radiation without any power consumption. However, the current low photoelectric performance of these detectors has hindered their practical use. In our study, a super-high-performance self-powered UV photodetector based on a GaN/Sn:Ga 2 O 3 pn junction was generated by depositing a Sn-doped n-type Ga 2 O 3 thin film onto a p-type GaN thick film. The responsivity at 254 nm reached up to 3.05 A/W without a power supply and had a high UV/visible rejection ratio of R 254 nm /R 400 nm = 5.9 × 10 3 and an ideal detectivity at 1.69 × 10 13 cm•Hz 1/2 •W −1 , which is well beyond the level of previous self-powered UV photodetectors. Moreover, our device also has a low dark current (1.8 × 10 −11 A), a high I photo /I dark ratio (∼10 4 ), and a fast photoresponse time of 18 ms without bias. These outstanding performance results are attributed to the rapid separation of photogenerated electron−hole pairs driven by a high built-in electric field in the interface depletion region of the GaN/ Sn:Ga 2 O 3 pn junction. Our results provide an improved and easy route to constructing high-performance self-powered UV photodetectors that can potentially replace traditional high-energy-consuming UV detection systems. KEYWORDS: self-powered, ultraviolet photodetector, GaN/Sn:Ga 2 O 3 pn junction, superhigh photoresponsivity, 3.05 A/W, potential barrier U ltraviolet radiation has a significant impact on humankind. Some benefits are UV's ability to facilitate the synthesis of vitamin D, kill germs, and treat or prevent rickets when our skin is exposed to moderate UV light. 1 However, it can cause cataracts and skin cancer and accelerate the aging process due to an excessive amount of UV radiation. 1,2 Additionally, UV radiation strongly affects the production of crops and the lifetime of buildings. Fortunately, UV radiation can be measured and monitored using semiconductor UV photodetectors based on Einstein's photoelectric effect, which transforms UV radiation to measurable electronic signals. After decades of steady development, modern UV photodetectors, with high performances in photoresponsivity, signal-to-noise ratios, stability, and speed, have gained interest recently for their applications in environmental monitoring, advanced communications, air purification, leak detection, space research, etc. 3−13 Unfortunately, to acquire reasonable detectivity, an external electric field is applied to photodetectors to separate the photogenerated electron−hole pairs. 5−13 Therefore, external power sources are generally necessary. This makes photodetectors overall uneconomical and complex. On the contrary, self-powered photodetectors can help solve the energy issues and have attracted significant attention. 14−19 Compared to traditional photodetectors, self-powered structures, based on the photovoltaic effect su...

A thin-film type β-Ga 2 O 3 /ZnO heterojunction was constructed for the first time by radio frequency magnetron sputtering of a β-Ga 2 O 3 layer on a (0001) ZnO single crystalline substrate. The heterojunction presents a typical positive rectification in the dark, and shows a solar-blind deep ultraviolet photoelectric characteristic. Under zero bias, the photodetector based on a β-Ga 2 O 3 /ZnO heterojunction exhibits an I photo /I dark ratio of ∼14.8 under a 254 nm light illumination with a light intensity of 50 μW cm −2 , showing a characteristic of working with zero power consumption. The photocurrent linear increases and the response time decreases with the increase of the light intensity. The photodetector shows a R λ of 0.35 A W −1 and an EQE of 1.7×10 2 % under 254 nm illumination of 50 μW cm −2 and a negative bias of 5 V. This study presents a promising candidate for use in solar-blind deep ultraviolet photodetection.

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The conductivity of gallium oxide thin films is strongly dependent on the growth temperature when they deposited by pulsed laser deposition under vacuum environment, exhibiting an insulative-to-metallic transition with the decrease of the temperature. The high conductive gallium oxide films deposited at low temperature are amorphous, non-stoichiometric, and rich in oxygen vacancy. Large changes in electrical resistance are observed in these non-stoichiometric thin films. The wide variety of hysteretic shapes in the I-V curves depend on the voltage-sweep rate, evidencing that the time-dependent redistribution of oxygen vacancy driven by bias is the controlling parameter for the resistance of gallium oxide.

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