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The coupling of pyroelectricity, semiconductor, and optical excitation yields the pyro-phototronic effect, which has been extensively utilized in photodetectors. It can also enhance the performance of light energy harvesting nanogenerators. In this work, a pyro-phototronic effect-enhanced MXene/ZnO heterojunction nanogenerator has been successfully demonstrated, which can harvest broadband light energy (from deep UV to near-infrared) and still operate at 200 °C. The morphology of the ZnO layer and the MXene layer's thickness have been further optimized for better light energy harvesting performance. For the optimized heterojunction nanogenerator, the responsivity can be improved from ~0.2 mA/W to ~3.5 mA/W by pyro-phototronic effect, under 0.0974 mW/cm2 365 nm UV illumination. Moreover, the coupling of pyro-phototronic and piezo-phototronic effects in MXene/ZnO heterojunction nanogenerators has been investigated. The results indicate that only a small tensile strain could improve the nanogenerator's performance. The working mechanisms have been carefully analyzed, and the modulation of piezoelectric charges on the Schottky barrier height is found to be the key factor. These results demonstrate the enormous potential of the pyro-phototronic effect in light energy harvesting nanogenerators and illustrate the coupling of pyro-phototronic and piezo-phototronic effects for further performance improvement. [ABSTRACT FROM AUTHOR]

The piezophototronic effect has been widely explored to improve the performance of optoelectronic devices. However, modulation of piezoelectric charges varies with different energy band structures. Thus, it is important to investigate the specific role of the piezophototronic effect from a theoretical perspective. Herein, the piezophototronic effect in anisotype p‐Si/n‐ZnO heterojunction photodiodes with type‐II energy band diagrams through analytical derivation and numerical simulation is thoroughly studied. It is found that both the depletion region and quasineutral region have a decisive effect on photocurrent in their respective regions. Specifically, modulations of piezoelectric charges on depletion region current and quasineutral region current are opposite and compensate each other, resulting in reduced piezophototronic effect. Heterojunctions under short diode conditions are preferred for better piezophototronic effect as modulation on quasineutral region current is weakened while that on depletion region current remains unchanged. The effects of doping concentration, absorption coefficient, and minority carrier lifetime of semiconductor materials on device characteristics are also studied. This work provides deeper insight into the underlying device physics of the piezophototronic effect. [ABSTRACT FROM AUTHOR]

In this paper, the properties of indium nitride (InN) semiconductor films deposited by magnetron sputtering were studied. The effects of different substrates (Al 2 O 3 , ITO and Si) and different nitrogen-argon flow ratios on the crystal quality of InN films were compared. The crystal structure, surface morphology, optical and electrical properties of InN films were systematically studied. The results showed that the crystallization quality of InN thin film was the best when the flow ratio of nitrogen to argon was 30/0 on Al 2 O 3 substrate. Then the p-NiO/n-InN/AlN heterojunction device was prepared on Al 2 O 3 by using AlN as buffer layer, and the electrical properties of the devices at different operating temperatures were analyzed. Finally, high rectification characteristics and good temperature stability were obtained. This study provides a reference for the preparation of InN films on different substrates and the application of InN-based devices. • The effects of different substrate types on the physical properties of InN films were studied. • The InN films with relatively good quality was obtained by magnetron sputtering. • Device with high rectification characteristics typical based on p-NiO/n-InN structure was prepared. • The influence of the operating temperature of the device on the rectification characteristics was studied. [ABSTRACT FROM AUTHOR]

The piezo‐phototronic effect has been extensively investigated to improve the performance of optoelectronic devices. However, the modulations in different energy band structures are quite distinctive, and adverse effects may be produced. Therefore, it is essential to investigate the modulation law in the optoelectronic devices with different energy band structures. Here, five kinds of Si/ZnO heterojunction photodiodes (PDs) with different energy band structures are fabricated and the piezo‐phototronic effect is systematically investigated on their photoresponse performance. For the p‐Si/n‐ZnO PDs, significant performance improvement is achieved by the piezo‐phototronic effect, with the magnitude of improvement increasing with doping concentration of p‐Si. For the n‐Si/n‐ZnO PDs, performance improvement is only achieved when the n‐Si is lightly doped, with a lower magnitude compared to that of the p‐Si/n‐ZnO PDs. The in‐depth working mechanism regarding to the different energy band structures is revealed. It is concluded that when the Fermi‐level of Si moves from the bottom of conduction band to the top of the valence band, the magnitude of performance improvement in Si/ZnO heterojunction PD increases. This study not only presents an in‐depth understanding regarding the piezo‐phototronic effect in Si/ZnO heterojunction PDs, but also provides guidance to optimize the piezo‐phototronic effect in optoelectronic devices. [ABSTRACT FROM AUTHOR]

Abstract: The piezo‐phototronic effect is confirmed as a promising methodology to optimize the performance of optoelectronic devices. However, not only positive effects, but also negative effects may be produced in some types of photodiodes (PDs) by the piezo‐phototronic effect, resulting in the restriction of the PDs' photoresponse performance enhancement. In order to obtain the largest possible photoresponse performance enhancement, it is essential to investigate how the piezo‐phototronic effect influences the photoresponse performance of PDs with different device configurations and structures. Here, the piezo‐phototronic effect on the photoresponse performance enhancement of anisotype (p‐Si/n‐ZnO) and isotype (n‐Si/n‐ZnO) heterojunction PDs is thoroughly investigated. The experimental results show that the piezo‐phototronic effect induced improvement of the p‐Si/n‐ZnO heterojunction PD is much larger than that of the n‐Si/n‐ZnO heterojunction PD. The energy band diagrams under compressive strains are carefully analyzed, revealing that two positive effects are introduced to the p‐Si/n‐ZnO heterojunction PD, whereas one positive and two negative effects are introduced to the n‐Si/n‐ZnO heterojunction PD by the piezo‐phototronic effect. This work presents an in‐depth understanding about the piezo‐phototronic effect on the photoresponse performances of PDs with different device configurations and structures. [ABSTRACT FROM AUTHOR]

In recent years, metal halide perovskite materials have attracted great attention in the field of optoelectronics due to their excellent physical properties. However, there are still some problems restricting its practical application. In this paper, a high-quality CsPbBr 3 film with good crystalline quality, compact surface morphology and excellent optical properties was obtained by thermal evaporation preparation and annealing optimization. On this basis, p-NiO/CsPbBr 3 /n-GaN heterojunction diode was prepared. At room temperature, the diode exhibits excellent electrical and luminous properties. The I–V curve shows typical rectification behavior. The luminous mechanism has also been deeply analyzed. In addition, the temperature dependence of the electrical properties was analyzed. According to the fitting and calculation, the temperature sensitivity coefficients for forward and reverse are 2.446 × 10−4 and −7.094 × 10−6 A/°C, and the activation energy is 0.31 eV. It is found that the ambient temperature has a great influence on the luminous properties of the diode. This study demonstrates the potential application of p-NiO/CsPbBr 3 /n-GaN heterojunction diode in the field of luminescence. • Green light-emitting diode based on p-NiO/CsPbBr 3 /n-GaN heterojunction was prepared. • The high-quality CsPbBr 3 film was obtained by evaporation and annealing treatment. • The diode exhibited excellent I–V and electroluminescence characteristics. • The influence of ambient temperature on the diode was studied. [ABSTRACT FROM AUTHOR]

CuO had huge application prospects in the fields of semiconductor optoelectronic devices. However, the preparation of high-quality CuO films was still an urgent problem to be solved. Herein, we prepared CuO films at different sputtering pressures (0.6–2.1 Pa) by magnetron sputtering technology. The experiment results showed that the sputtering pressure had an obvious effect on the optical properties, structure, morphology and electrical properties of CuO films. It showed that relatively better CuO films could be prepared at 1.6 Pa. Moreover, Hall effect indicated that the change of ambient temperature had an obvious effect on the resistivity and carrier concentration of CuO films. Correspondingly, the p-CuO/n-GaN heterojunction device was fabricated, and the relationship between carrier transport characteristics and ambient temperature was studied. Ambient temperature had obvious influence on the turn-on voltage and rectification ratio of the device. This work provided a basis for the practical application of CuO-based optoelectronic devices. • The effect of sputtering pressure on the physical properties of CuO film was studied. • The effect of ambient temperature on the electrical properties of CuO films was studied. • Device with high rectification ratio based on p-CuO/n-GaN structure was prepared. • The influence of operating temperature on the carrier transport properties was studied. [ABSTRACT FROM AUTHOR]

In recent years, GaN materials have been applied to the field of optoelectronic devices due to their excellent photoelectric properties, especially in the field of light-emitting diodes, which has attracted considerable attention. In this article, we use structural engineering methods to further improve the performance of GaN-based ultraviolet light-emitting diodes. The magnetron sputtering and annealing treatment were used to prepare ultraviolet light-emitting diodes based on p-NiO/i-Ga 2 O 3 /n-GaN and p-NiO/n-GaN heterojunction structure. X-ray diffractometer, field emission scanning electron microscope and ultraviolet-visible spectrophotometer were used to study the crystal quality, surface morphology, and optical properties of Ga 2 O 3 film. Compared with the p-NiO/n-GaN heterojunction diode, the p-NiO/i-Ga 2 O 3 /n-GaN heterojunction diode exhibits better rectification characteristics and more excellent electroluminescence characteristics. Under the injection voltage of 35 V, the EL spectrum intensity of p-NiO/i-Ga 2 O 3 /n-GaN heterojunction diode is nearly 37 times higher than that of p-NiO/n-GaN heterojunction diode. Finally, the working mechanism of the electroluminescence is analyzed in detail through the energy band diagram of the two diodes. [ABSTRACT FROM AUTHOR]

• Near-white LED based on p-CuO/i-CuO/n-GaN was realized by magnetron sputtering and annealing treatment. • CuO could be used as hole injection layer and electron blocking layer under different annealing condition. • The chromaticity coordinates and related color temperatures of the devices were about (0.2381, 0.2606) and 22,505 K. • The i-CuO layer could improve the stability of electron injection and optimize the structure of diode. White light-emitting diodes (WLEDs) have advantages of high efficiency, energy saving, and long working-life, which are ideal choice for next generation of solid-state light sources. Herein we fabricated the near-white light-emitting diode based on the structure of p-CuO/i-CuO/n-GaN heterojunction by magnetron sputtering and annealing treatment. The surface morphology, crystal quality and electrical properties of the CuO layer were investigated by X-ray diffractometer, field emission-scanning electron microscope and Hall measurement. And the influence of the CuO electron blocking layer (EBL) on the diode characteristics were discussed. The current-voltage (I-V) characteristics of those diodes revealed typical p-n junction. Compared with p-CuO/n-GaN heterjunction diode, the EL spectrum of p-CuO/i-CuO/n-GaN heterjunction diode exhibited blue shift and higher intensity. It was found that the addition of CuO EBL enhanced the stability of the diode through analyzing the I-V and EL properties of the diodes. Moreover, at the injection current of 50 mA, the chromaticity coordinates of p-CuO/n-GaN and p-CuO/i-CuO/n-GaN heterojunction diodes are about (0.2686, 0.3334) and (0.2381, 0.2606), and the color temperature are 9205 K and 22,505 K, respectively. Eventually, the EL working mechanism of the two diodes was analyzed in the aspect of the energy band diagram. This study demonstrates the possibility of p-CuO/n-GaN heterojunction with an i-CuO electron blocking layer and their potentials for applications in WLEDs. [ABSTRACT FROM AUTHOR]

With the progressively prominent impact of pollution caused by the extensive use of unsustainable fossil energy on the environment, clean energy with solar energy as an important component is developing rapidly. As a p-type semiconductor material with excellent performance, CuO is expected to become one of the most competitive photovoltaic materials in the field of optoelectronic devices. We first explored the effects of changing the sputtering power on the crystalline quality of CuO thin films, and systematically investigated the crystal structure, surface morphology, optical and electrical properties. Then we fabricated an Au/p-CuO/n-Si/Al heterojunction solar cell by magnetron sputtering and analyzed the influence of the device on the electrical properties at different temperatures. High rectification characteristics typical of diodes were obtained. Finally, by measuring and calculating the photovoltaic performance of the device under simulated sunlight irradiation, we studied the dependence of the device operating temperature on the photoelectric conversion efficiency in detail. • The effect of sputtering power on the physical properties of CuO film was studied. • The CuO film with relatively good quality was obtained by magnetron sputtering. • Device with high rectification characteristics typical based on p-CuO/n-Si structure was prepared. • The operating temperature dependence on the photoelectric conversion efficiency of the device was studied. [ABSTRACT FROM AUTHOR]

• An n -ZnO/p-Si/ n -Si heterojunction bipolar phototransistor was proposed to detect the visible light and the X-ray. • The detector fabricated using the sputtering method shows linear and repeatable response to the visible light, and has a fast response with a decay time of about 7.75 μs. • The high sensitivity and well repeatable response of the n -ZnO/p-Si/ n -Si detector to the X-ray indicates its potential in the nuclear-radiation detection applications. We fabricated an n -ZnO/p-Si/ n -Si heterojunction bipolar phototransistor by the low cost RF magnetron sputtering method and characterized its photoresponse to both the 780 nm visible light and the X-ray in this paper. The device structure and the film transmittance were characterized by the SEM, XRD and transmittance spectra. The phototransistor shows high sensitivity, linearity and repeatable response to both the 780 nm visible light and the X-ray illumination indicating the promising potential of the n -ZnO/p-Si/ n -Si detector. The sensitivity of the phototransistor to the X-ray is about 280 μC·Gy−1·cm−2 under the bias voltage of 10 V with the X-ray tube voltage of 30 kV. The phototransistor also shows a fast response with a decay time of about 7.75 μs, which corresponds to the lifetime of the sputtered p-Si film. The temperature dependent dark current of the device indicated the activation energy of 0.32 eV, which is probably caused by the deep-level defect in the high resistivity silicon substrate. The photo current of the phototransistor to the 780 nm visible light linearly increases with increasing the bias voltage in the saturation region indicating an Early voltage of about 5.6 V, from which the effective impurity density of the p-Si film was deduced to be ∼1 × 1016 cm−3 revealing the low activation rate of the sputtering method, and the unactivated dopant could act as recombination centers and responsible for the short carrier lifetime of the p-Si film and the fast response of the phototransistor. This paper demonstrated that the n -ZnO/p-Si/ n -Si heterojunction bipolar transistor has potential for the development of an X-ray detector. [ABSTRACT FROM AUTHOR]

The good properties of ITO substrate endow the as-grown InN thin films especially attractive for various optoelectronic applications. Herein, the InN thin films were prepared on the ITO substrates by magnetron sputtering. The effects of substrate temperature (T s) on the structural, morphological, and optical properties of InN films were assessed by X-ray diffractometer, scanning electron microscope and ultraviolet–visible spectrophotometer. The combination of structural and morphological investigation suggested that the better InN thin film was obtained at 200 °C. Then, the variation of the optical band gap and transmittance with T s was discussed. What's more, the p-NiO/n-InN heterojunction was trial-produced, and the carrier transport characteristics were studied in the range of 30–120 °C. The heterojunction exhibited excellent I–V characteristics at all operating temperatures. This work enriches the description of InN materials and devices, and provides a useful reference for the practical application of InN. • High-quality InN thin film was obtained on the ITO substrate by magnetron sputtering. • The increase of substrate temperature was conducive to the growth of InN (101) plane. • High rectification ratio diode based on p-NiO/n-InN structure was trial-produced. • The diode also exhibited superior I–V characteristics under high temperature. [ABSTRACT FROM AUTHOR]