Strain-enhanced Cable-type3D UV Photodetecting Of ZnO Nanowires On A Ni Wire By Coupling Of Piezotronics Effect And Pn Junction

UV photodetecting and piezoelectric properties of one-dimensional ZnO NWs haveattacted extensive attention due to the superior optical and electrical properties of ZnO.Based on the pn junction grown on cylindrical metal wire, the fabrication process,morphology analysis, measurement of the optical, electrical and piezoelectric propertieshave been carried out in this research. The main results are listed as follows:(1) ZnO nanowires with a length of5μm and diameter of30nm have beensuccessfully synthesized on an Au coated oxidized Ni wire using the simple andconvenient CVD method. The growth mechanism of ZnO NWs and the effect of gaspressure which may have on the morphology of ZnO NWs were carefully investigated.(2) The photoluminescence (PL) spectra of the device shows a sharp UV peak ataround380nm and a negligible peak at around520nm, which are the near-band-edgeemission (NBE) and deep-level emission (DLE), respectively. The result indicates that theas-prepared ZnO NWs are well crystallized and low concentration of defects. The UVphoto sensing properties of the p-NiO/n-ZnO NWs heterjunction shows the apparent UVresponse characteristics with a bias of1V under the illumination of a high pressuremercury lamp. The response and recovery time are calculated as7.5s and8.6s,respectively. After changing the bias voltage and rotation angle, the UV responseproperties remained stable, which demonstrates a prospective approach to3Dphotodetecting.(3) A home made probe table was used the measure the piezoelectric properties of thedevice, the results shows that the photocurrent increases with the increase of compressivestrains. In addition, the mechanism of the enhanced photocurrent was explained from thepoint of the modification the energy bands.