Most of the photodetectors can measure all of the light illumination with a wavelength below the absorption edge of the detector materials, while they cannot distinguish the different waveband. Herein, a self-powered spectrum-distinguishable photoelectrochemical (PEC) type photodetector based on an α-Ga2O3 nanorod array (NA)/Cu2O microsphere (MS) p–n junction was reported. Under the combined action of the built-in electric field of the p–n junction and the semiconductor/electrolyte junction, the photodetector exhibits an opposite direction of the photocurrent to the illumination of 254 and 365 nm UV light under the applied bias of 0 V, which can be used to distinguish the different wavelengths of light. The photodetector shows a responsivity of 0.42 mA/W under 254 nm UV light and 0.57 mA/W upon 365 nm, respectively. Our results provide an idea for distinguishing the different illumination wavebands through a photodetector constructed by the heterojunction with two different band gap materials.

Solar-blind photodetectors have been widely developed because of their great potential application in biological analysis, ultraviolet communication, and so on. Photodetectors constructed by vertically aligned nanorod arrays (NRAs), have attracted intensive interest recently owing to the virtues of low light reflectivity and rapid electron transport. However, limited by the insufficient contact between the upper electrode and NRAs because of uneven NRAs, photogenerated carriers cannot be effectively separated and transferred. In this work, a novel photoelectrochemical (PEC) type self-powered solar-blind photodetectors constructed in the form of Ga2O3 NRAs/electrolyte solid/liquid heterojunction with a large photogenerated carrier separation interface has been fabricated, β-Ga2O3 NRAs PEC photodetector shows a photoresponsivity of 3.81 mA/W at a bias voltage of 0 V under the 254 nm light illumination with the light intensity of 2.8 mW/cm2, thus yielding a I photo/I dark ratio of 28.97 and an external quantum efficiency of 1.86%. Our results provide a novel device structure of solar-blind photodetector with high efficient deep-ultraviolet photodetection and low power consumption.

Vertically aligned β-Ga2O3 nanorod arrays with high light coupling and rapid electron transport were assembled for solar-blind deep UV detection.

No abstract

Recently, α-Ga2O3 nanorod array (NRA)-based deep ultraviolet (DUV) photodetectors have attracted more and more attention in the optoelectronic field due to their wide band gap, highly effective detection area, and simple preparation method. Unfortunately, the large number of defects in the α-Ga2O3 NRAs hinder the transportation of charge carriers, resulting in a low on–off ratio, low responsivity, and low detectivity. Wide band gap materials such as TiO2 and Al2O3 are often used as surface passivation layers to passive the defects in semiconductors, which is an effective way to improve the performance of photodetectors. Herein, an α-Ga2O3–TiO2 core–shell NRA-based photovoltaic-type DUV photodetector with an optimized graphene upper electrode has been successfully fabricated. Thanks to the passivation effect and type-II staggered band alignment of α-Ga2O3 and TiO2, the photogenerated carriers can be separated and transported efficiently. The α-Ga2O3–TiO2 core–shell NRA photodetector exhibits a large photocurrent of ∼110.88 nA, a responsivity (R) of 0.176 mA/W, a photoresponse speed of 0.72/0.14 s, and an I dark/I photo current ratio of 616 under 254 nm light at 0 V. In addition, the effect of humidity on the α-Ga2O3–TiO2 NRA device has been studied, and a proposed model of the mechanism has been built. Our research suggests a possible technique for developing high-performance α-Ga2O3 NRA-based photodetectors, which has the potential to further their applications.

Parasitic absorption in the front window layers of transparent conductive oxide (TCO) films and carrier selective collection layers and the optical shading losses from the metallic finger grid mainly limit the current generation in silicon heterojunction (SHJ) solar cells. In this work, we demonstrate an improved short-circuit current density (J sc ) of 40.24 mA/cm 2 through a combination of novel window layers composed of transition metal doped indium oxide (IMO) and hydrogenated nanocrystalline silicon oxide (nc-SiO x :H) films and Cu plating for SHJ solar cells. By introducing water vapor during direct current (DC) magnetron sputtering deposition process, IMO films show a large optical band gap (E g ) of about 3.88 eV and high mobility up to 83.2 cm 2 /VÁs, while maintaining a low carrier concentration, which leads to high transparency and low near-infrared (NIR) free carrier absorption (FCA). In addition to its high deposition rate and crystalline volume fraction, we found that nc-SiO x :H films deposited by very high frequency (VHF) excited plasma-enhanced chemical vapor deposition (PECVD) show an excellent surface passivation quality, which not only improves the open circuit voltage (V oc ) of SHJ cells but also increases the J sc through improved carrier selective collection. The quantified J sc breakdown analysis was performed to identify the room for improvement, and it showed that the front shading loss (about 1.32 mA/cm 2 ) is the largest portion. By combining the benefits of these window layer enhancements with the further use of fine line width and conductivity of Cu plating, SHJ solar cells, with a J sc improvement of 0.57 mA/cm 2 and a certified efficiency of 25.54%, were achieved on a total area of 274.5 cm 2 using in-house pilot production line equipment.

No abstract