The Preparation And Performance Of Photodetectors Based On SnO₂ Nanobridge

The photodetector is a device to convert optical signals into electrical signals.As the photoelectric switch,it is essential in many photoelectronic circuits.Compared with the traditional single nanowire devices,the photodetectors based on the "nanobridge" have many advantages: simple fabrication,low cost,short time,high sensitivity and so on.In this paper,we prepared photodetectors based on single SnO₂ nanowire and SnO₂ "nanobridge" through two kinds of preparation process.At the same time,the mechanism of enhanced performance of "nanobridge" device have been studied.Firstly,by the vapor phase transport method,we have obtained SnO₂ nanowires with high pure tin particles as raw materials at 900?.Then,we prepared the photodetector based on single SnO₂ nanowire by means of mechanical probe transferring,and the photoresponse of the device was tested.Secondly,we obtained the photodetector based on SnO₂ "nanobridge" by the method of in situ growth.Similarly,the photoresponse of the device was tested.Finally,we compared with the photoresponse properties of single nanowire device and "nanobridge" device.The results showed that the "nanobridge" device had higher photosensitivity.Further compared with the structures of two kinds of devices,we found that the nanowires between the electrodes of the "nanobridge" device had both junction nanowires structure and multiple nanowires structure.Next,we also studied the dark current,photocurrent and on/off ratio of two kinds of devices.The experimental data showed that the "nanobridge" device had smaller dark current,larger photocurrent and higher on/off ratio.In order to explore the relationship between the enhanced performance and nanowires configurations of "nanobridge" device,we prepared crossing SnO₂ nanowires device.And based on the same device,we studied the photoresponse of single nanowire device,junction nanowires device and double nanowires device.The experimental results showed that the junction nanowires device had lower dark current,and the double nanowires device had higher photocurrent.Thus,we hypothesized that the higher photosensitivity of “nanobridge " device may come from the following two reasons: first,the crossing nanowires junctions formed between the electrodes of “nanobridge" device reduced the dark current;second,more nanowires between the electrodes of "nanobridge" device enhanced the photocurrent.