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The flexible ultraviolet (UV) photodetector (PD) has stable performance under mechanical flexibility to be applied on uneven surfaces. This provides a lot of freedom for redesigning photoelectric applications, so people highly regard it. We have studied the UV PD of Mg0.2Zn0.8O (MZO) film by radio frequency magnetron sputtering on flexible polyethylene terephthalate substrates to improve the photoelectric performance. Through the photoelectric performance analysis and comparison of the three PDs of MZO, ZnO1h/MZO, and ZnO2h/MZO, we found that the performance of PD containing ZnO film has been dramatically improved. Under 8 V bias, their responsivity was enhanced by 51 and 210 times, and the detectivity was enhanced by 2 orders of magnitude. Under 24 V bias, their responsivity is improved by 308 times and 1130 times, and external quantum efficiency is more than 1000%. Our findings provide a simple and easy way to achieve high-performance flexible MZO UV PD. [ABSTRACT FROM AUTHOR]

In this article, novel sandwich-structured surface plasmon ultraviolet (UV) photodetectors based on ZnO thin films with engineered rear metal electrode were fabricated by radio-frequency magnetron sputtering. An exhaustive study about the impact of a dissimilar metallic layer (Au and Pt) on the structural, optical, and electrical properties of the device was carried out. The carrier collection property of the sandwich structure devices has the advantages of horizontal and vertical joint collection. In theory, adding a new metal semiconductor layer introduces a contact area and increases the resistance. An ultra-low dark noise current of less than 2.0 × 10–7 A and a responsivity exceeding 1.6 A/W were achieved with the prepared ZnO-based UV-PDs in the rear metallic electrode mode. The devices based on the ZnO/Pt/ZnO and MgZnO/Pt/MgZnO sandwich structures show high responsivity and fast response. This study provides a depletion layer width method for the fabrication of high-response UV photodetectors for surface plasmon-based materials by integrating metal semiconductor nanostructures. A homogeneous two-layer UV photodetector is constructed, which changes the traditional single-layer device structure and overcomes drawbacks of the single device structure. [ABSTRACT FROM AUTHOR]

The formation of a broadband photodetector with high response, high sensitivity and controllable band is a major challenge to improve the application range of photodetectors. The integration of quantum dots and highly conductive materials is one of the important approach for the application of broadband photodetectors. In this work, ultraviolet–visible–near infrared (UV–Vis–NIR) sensitive PD consisting of ZnO film/PbS quantum dots (QDs) heterostructure was proposed. While forming a built-in electric field, the heterostructure also generates a barrier to prevent carrier recombination, so that the heterostructure PD has excellent photoresponse performance in the UV–Vis–NIR range, and the peak responsivity is increased by 550%. Increased from 0.974 mA/W to 6.332 mA/W, accompanied by obvious red shift, faster response and recovery speed compared to pure ZnO film PD. Different from other experiments, in order to make the performance gain of PbS QDs on ZnO film more obvious and intuitive, this article uses RF magnetron sputtering to prepare ultra-thin ZnO film, and discusses the impact of PbS QDs on the photoelectric properties of ZnO film more comprehensively and systematically. The performance of the broad spectrum in this experiment will be of great help to the research and application of ZnO PD in the future. • Ultraviolet–visible–near infrared (UV–Vis–NIR) sensitive PD consisting of ZnO film/PbS quantum dots (QDs) heterostructure was proposed. • While forming a built-in electric field, the heterostructure also generates a barrier to prevent carrier recombination, so that the heterostructure PD has excellent photoresponse performance in the UV–Vis–NIR range, and the peak responsivity is increased by 550%. Increased from 0.974 mA/W to 6.332 mA/W, accompanied by obvious red shift. • Faster response and recovery speed compared to pure ZnO film PD. • Discusses the impact of PbS QDs on the photoelectric properties of ZnO film more comprehensively and systematically. [ABSTRACT FROM AUTHOR]

Metal-semiconductor-metal (MSM) ultraviolet photodetector is fabricated on ZnO films, prepared by radio frequency magnetron sputtering technique on quartz substrates. The ZnO photodetector shows low dark current and external quantum efficiency (EQE) due to the gain effect. The device also exhibits a near linear responsivity dependence on voltage, which gradually rise to the peak first, then fall sharply, and then slightly rise again. A physical mechanism primarily focused on the relationship between carrier (electron-hole pairs) transport and barrier height at Schottky metal-semiconductor contact is given to explain the above phenomena. It is demonstrated as a straightforward and convenient way to enhance the internal gain of the simple ZnO-based Schottky photodetectors for application in the future. [ABSTRACT FROM AUTHOR]

The dual-wavelength UV photodetector (PD) with sandwich structure of ZnO/Au/MgZnO/SiO2 was fabricated and investigated with an emphasis on the effects of the Ag nanoparticles localized surface plasmons (LSPs). The results demonstrated that the modification in Ag nanoparticle (NP) position played a remarkable influence on the performance of dual-wavelength UV photodetectors. In comparison with decorating Ag NPs on the surface of the PDs, embedding Ag NPs between the MgZnO and ZnO films could improve two peak responsivities (caused by MgZnO and ZnO layers) significantly. By calculating the responsivities enhancement ratio of double layers (MgZnO and ZnO), the results indicated that the enhancement ratio of MgZnO is higher than that of ZnO. This was ascribed to LSPs of energy match with MgZnO which was superior to ZnO. This work described a creative method for increasing the performance of dual-wavelength UV PDs. [ABSTRACT FROM AUTHOR]

Exploiting piezo-phototronics effect of ZnO film ultraviolet (UV) photodetector (PD) has been confirmed as a promising way to optimize the performance of flexible devices. A flexible ZnO film UV PD was fabricated on polyethylene terephthalate substrate by utilizing radio frequency sputtering technology and conventional photolithography. The responsivity of obtained device showed a threefold increase under 10.99% tensile strain. Moreover, the device maintained good reproducibility and stability after continuous bending cycles (25/50/75/100). Separation and transport of photogenerated electron–hole pairs are responsible for the enhanced performance, which is influenced by band structure change and piezoelectric polarization at the ZnO/Au interface. The attributes of high stability, reproducibility, and sensitivity of this flexible ZnO film UV photo detector indicate that the proposed method is a promising approach to optimize flexible ZnO film optoelectronic devices based on piezoelectric effect. [ABSTRACT FROM AUTHOR]

A ZnO film with a c-axis preferred orientation was prepared on quartz using the radio frequency (RF) magnetron sputtering technique. Then, a metal-semiconductor-metal (MSM)-structured ultraviolet (UV) photodetector was fabricated on the film. It was found that the cutoff wavelength of the photocurrent redshifted from 361 to 379 nm when the bias increased from 5 to 30 V. The origin of the redshift has been interpreted in terms of a qualitative model considering the declining band gap caused by the bias. This method opens up the possibility of tuning the cutoff redshift of ZnO UV photodetectors. [ABSTRACT FROM AUTHOR]

• Two Ag nanoparticle layers were embedded in the ZnO film as forming the ZnO/Ag/ZnO/Ag/ZnO multilayer structure. • With decreased spacing between two Ag nanoparticle layers, UV photodetector responsivity was gradually enhanced. • The absorption band-edges of ZAZAZ multilayer-structured PDs showed a redshift in comparition with the bare ZnO film. In this study, the ZnO/Ag/ZnO/Ag/ZnO (ZAZAZ) multilayer-structured UV photodetectors (PDs) were fabricated and investigated with an emphasis on the effects of the spacing between the two Ag nanoparticle (NP) layers. The results indicated that embedding two Ag NP layers can significiantly improved UV PD responsivity. Owing to optimazation of the spacing between the two layers, responsivity of multilayer- structured PDs was enhanced from 11.69 to 24.32 A/W. Also, the absorption band-edges and photoresponse cutoff wavelength of ZAZAZ multilayer-structured PDs showed a significant redshift in comparition with the bare ZnO photodetector. This was ascribed to near-field effects of surface plasmons. This novel research described a creative method for increaing the performance of ZnO PDs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sandwich–structured photodetector (SSPD) was successfully constructed. • Ga 2 O 3 thin films were grew on the electrode region of ZnO/Au MSM–structured devices. • Back side illumination and embedded electrodes led to increase in EQE of the SSPD. • Increased EQE of SSPD at 30 V is 18 times (654 %) that of traditional ZnO/Ga 2 O 3 /Au PD. In this study, sandwich–structured photodetector (SSPD), a new type of structure of PD based on traditional metal–semiconductor–metal (MSM) structure, was designed and fabricated to solve the difficult problem of weak light detection caused by the low gain of PDs with the traditional structure. Herein, zinc oxide/gold/gallium(III) oxide (ZnO/Au/Ga 2 O 3) SSPD with a high external quantum efficiency (EQE) was successfully constructed by growing Ga 2 O 3 film layer on the electrode area of the ZnO/Au MSM–structured device. The high EQE originates from the backlight–type irradiation and embedded electrodes of the special sandwich structure existing in the ZnO/Au/Ga 2 O 3 SSPD. The ZnO/Au/Ga 2 O 3 SSPD shows EQE of up to 11626 % at 30 V, which is 18 times (654 %) higher than that of the traditional MSM–structured ZnO/Ga 2 O 3 /Au PD. These results indicate that the research provides a new and effective method to increase the performance of Ga 2 O 3 –based PDs. [ABSTRACT FROM AUTHOR]

• High Mg-content single-phased wurtzite Mg 0.51 Zn 0.49 O films realized by a facile RF magnetron sputtering technique on quartz (SiO 2) substrates. • The solar-blind and visible-blind dual-band UV PDs based on W-Mg 0.51 Zn 0.49 O films heteroepitaxial growth on ZnO buffer layer (30 min) exhibited significantly enhanced properties especially the specific detectivity (1012 Jones) in solar-blind region. • The performances improvement through adhesion strength between W-Mg 0.51 Zn 0.49 O and ZnO BL provide a feasible way to improve the detection ability of solar-blind region in dual-band UV PDs. High Mg-content single-phase wurtzite Mg 0.51 Zn 0.49 O (W-Mg 0.51 Zn 0.49 O) films were realized by radio frequency (RF) magnetron sputtering technique on quartz (SiO 2) substrates. The metal-semiconductor-metal (MSM) solar-blind (SB) and visible-blind (VB) dual-band ultraviolet (DB-UV) photodetectors (PDs) were also fabricated based on heteroepitaxial growth of W-Mg 0.51 Zn 0.49 O films on ZnO buffer layer (BL) at different nucleation states. Under 270 nm of irradiation, the Au/Mg 0.51 Zn 0.49 O/ZnO (30 min) PD exhibited an optimal external quantum efficiency (EQE, 304.4%) and specific detectivity (1012), which indicated that the ZnO BL obtained with a 30 min treatment time was most efficient to improve the detection of SB-UV wavelength. The origin of these results was attributed to the contact area and adhesion strength between MgZnO and ZnO matrices. The results showed a feasible way to obtain high Mg-content wurtzite MgZnO alloys and performance improvement through ZnO BL, which is favorable to the applicability in SB/VB DB-UV PDs. [Display omitted] [ABSTRACT FROM AUTHOR]

A novel Al-doped (3 wt%) ZnO (AZO) UV photodetector (PD) and ZnO/AZO heterojunction double-layer UV PD were prepared on a polyethylene terephthalate (PET) substrate by utilizing the radio frequency (RF) sputtering technology and conventional photolithography. Because the ZnO/AZO heterojunction possesses the ability to improve the separation of the photogenerated electron-hole pairs, the responsivity of the ZnO/AZO PD is higher than that of the pure AZO PD under the same bias voltage. Moreover, the responsivity of the obtained ZnO/AZO PD showed a 1.13 fold increase from 5.91 to 6.70 A/W when the tensile variable ɛ was 0.16. These findings also provide a new alternative for the preparation of flexible UV PDs with piezo-phototronic effect, which is low-cost and offers environmental sustainability. [ABSTRACT FROM AUTHOR]

In order to create ultraviolet photodetectors with a high sensitivity, high detection rate, and high responsivity, the lateral growth of ZnO nanowires arrays was controlled on a quartz substrate by using a hydrothermal method. The combined effects of the ZnO seed layer and the high quality of the crystalline nanowire arrays with different lengths greatly improved the performance of the photodetectors. The photocurrent in the photodetectors prepared with the lateral nanowires was 103 times higher than that of the photodetector prepared with a ZnO film due to the photoconductive gain of nanowires. As the nanowire length increased, the responsivity increased and then decreased due to the surface action of nanowires and the influence of interpolation space. The ZnO nanowire photodetector with the optimal length showed significant performance improvements including a higher responsivity, larger detectivity, lower NEP, and extremely enhanced EQE of 14.9 A/W, 2.3 × 1012 jones, 3.0 × 10−13 WHz−1/2 and 5.0 × 103%, respectively. The controlled growth of lateral nanowires for use in high-performance photodetectors provides a feasible way to realize high efficiency light detection in future optoelectronic applications. • We demonstrate a series of high-performance ZnO lateral nanowires ultraviolet photodetectors via hydrothermal synthesis. With the aid of the ZnO nanowires array, which show strong surface action, the performance of the ZnO photodetectors is greatly enhanced. • With the increase of nanowires length, the responsivity decreases after increasing, which is attributed to the surface action of nanowires and the influence of interpolation space. • This ZnO nanowires photodetector with proper length significantly accelerates the performance which is observed along with higher responsivity, larger detectivity, lower NEP, and extremely enhanced EQE. Controlled lateral nanowires with high-performance photodetectors provide a feasible way to realize high efficiency for future optoelectronic applications. [ABSTRACT FROM AUTHOR]