Enhanced photo-response properties of a single ZnO microwire photodetector by coupling effect between localized Schottky barriers and piezoelectric potential

Abstract

The coupling effect between localized Schottky barriers (SBs) and piezoelectric potential that impact the photo-response properties of a single ZnO microwire (MW) photodetector (PD) is studied. Localized SBs is introduced by Au NPs decoration. The negatively charged Au NPs deplete more carriers near the ZnO surface, which raises the SB height and sharply reduces the recover time of the PD from 142.4 s to 0.7 s. Moreover, after applying the compressive strain, the band structure of ZnO MW changes and piezoelectric potential generates, which further raises the SB height, thickens the depletion region and improves photo-response properties of the detector. The dark current is reduced by about 5 orders and its on/off current ratio increased by about 6 orders, which decreases the power consumption of the detector significantly. Under the above coupling effect between piezoelectric potential and localized SBs, the recover time of the detector is further reduced to 0.1 s ultimately. This work suggests that rational integration of localized SBs and piezoelectric potential is a viable approach to get ZnO MW PDs with high on/off ratio, ultrafast response speed and low power consumption.

Piezotronic and piezo-phototronic logic computations using Au decorated ZnO microwires

“…Our previous studies proved that the coupling between piezoelectric potential and numberd SBs (by Au NPs decoration) at the ZnO surface can much enhance the sensitivity of the piezoelectric devices. [23] For the Au NPs decorated piezoelectric transistor, the electrical transport properties of the device will be controlled more effectively by both the SB at the electrode contact and numberd SBs on the surface. The coupling among the characteristics of piezoelectricity, photoexcitation and semiconductor are enhanced because the numbered decorated Au NPs on the ZnO surface play the role of SBs, which supplies new and important control for field-effect-transistor (FET).…”

“…In our previous study, we proved that the localized SBs (by Au NPs decoration) at the ZnO surface is much enhanced the sensitivity of the piezoelectric devices. [23] Therefore, we believe that the numberd SBs can be functioned as traditional SB at the electrode to improve performance of the device, and using the coupling effect of piezoelectric potential and localized SBs to fabricate piezoelectric two-terminal transistors must be important to enhance the current on/off ratio of the devices.…”

Enhancing performance of Ag–ZnO–Ag UV photodetector by piezo-phototronic effect

“…Considering that the device is much smaller than the PB, shiing the 3D mechanical stage down for 1 cm equals to subjecting a tensile strain to the photodetector. 29,30 On the contrast, when shiing up the 3D stage, the photodetector receives a compressive strain. The deformation of photodetector 3 can be calculated from 3 ¼ d/2R, where d is the up/down moving distance of 3D stage, R is the bending curvature.…”

“…Therefore, according to the piezo-phototronics theory, the performance of the UV photodetector can be monitored and strengthened by external strain. 29 Conventional UV photodetectors are usually manufactured on hard substrates like silicon, sapphire, ITO glass and all kinds of metal foil. With the revolution of science and technology, so portable electronic devices which remarkably facilitate people's life have shown large scientic potential and commercial perspective.…”

Direct Catalyst‐Free Chemical Vapor Deposition of ZnO Nanowire Array UV Photodetectors with Enhanced Photoresponse Speed

“…We estimated the time constants of rise stage are t 1 ¼ 6.27 s and t 2 ¼ 37.1 s, and their relative weight factors are 85 and 15%, respectively, which give an average rise time constant of t r ¼ 11.02 s; the estimated time constants of the decay stage are t 1 ¼ 0.28 s and t 2 ¼ 6.85 s, with relative weight of 67 and 33%, respectively, producing an average decay time constant t d of 2.43 s. It was found that the rise process of NW array PD (1.38 s) is much faster than that of single NW PD (11.02 s), while the resetting process of ZnO NW array PD (4.05 s) is also comparable with that of single NW device (2.43 s). [6,9,11,14,16,19,20,22,25,27,[33][34][35][36][37][38][39][40][41][42] Compared to low temperature synthesized ZnO nanorods reported in reference, [35,36] ZnO NW arrays grown by CVD at high temperature have better crystal quality, which contributes to the high performance of our devices. Table 1 compares the photoresponse of different ZnO NW-based UV PDs as reported previously.…”