ZnO Nano UV Focal Plane Detector Chip Technology Based On Flexible Substrate

In this paper,the traditional microelectronic on-chip fabrication process and nanotechnology were combined to synthesize lateral bridged ZnO nanowire on flexible polymer substrates,so as to fabricate the UV focal plane detector arrays with large-scale,high uniformity and electrical stability.The main innovative results of this paper are as follows:1.We fabricated UV sensors based on lateral bridged ZnO NW on ordinary smooth polyimide?PI?substrates and PI substrates with special texture structures.Comparison of experimental results shows that sensors on ordinary smooth PI substrate have cracked during the device fabrication process due to the residual stress caused by temperature,humidity,etc.These cracks were short pieces and randomly distributed,so they may not significantly affect the device performance,but after mechanical bending,cracks that penetrating electrodes were generated and caused electric contact failure.Although improving the ZnO seed layer quality could reduce the cracking and buckling that formed during device fabrication,it would not prevent cracking during mechanical bending.In a 3×3 sensor array,only one sensor survived after bending.Device failed when the bending angle larger than-40° or 60°.On the contrary,device fabricated on textured PI substrates exhibited much better electrical stability.All the sensors remained their original performances after mechanical bending in a 3×3 sensor array.The light-dark current ratios kept in the level of 10⁵ under the 365nm UV light of15mW/cm² and 1V bias voltage.The bending angle varied from-80° to 80°.The enhancement of electrical stability was because that textured substrate could tolerate more stress than smooth substrate to prevent the film from cracking,and at the same time it could increase the contact area between ZnO film and PI substrate,which improved the interfacial bonding strength and delayed the local strain of the film.2.The flexible UV focal plane detector array based on lateral ZnO NW array was prepared on a flexible substrate.The array consists of 32×32 detection cells with a single pixel size of 60×125?m² and pixel center-to-center spacing of 150?m.100%of the sensors in the array were capable of responding to incident UV light and exhibited high uniformity?the nonuniformity of photocurrent was 44%?.Under the 365nm UV light of 5mW/cm² and 1V bias voltage,the average light-dark current ratio of the detector array can reach¹.1×10⁵,average responsivity can reach⁹23 A/W,and average detection rate can up to².5×10¹⁴ Jones.The flexible focal plane detector array also exhibited excellent flexibility and electrical stability under the bending state.