Controllable Growth Of Low-dimensional AlN Nanomaterials And Preparation Of MSM Ultraviolet Detector

Rencently,low-dimensional nanostructured materials have shown potential application prospects in many fields due to their novel physical and chemical properties.As the third generation of semiconductor material,AlN has many excellent properties,like wide band gap,high surface acoustic wave velocity,and good thermal conductivity,and has become the first choice in ultraviolet and deep ultraviolet electronic devices.However,fabricating high-performance UV detector based low-dimensional AlN nanomaterials remains a challenge because of some difficulties.For example,size and structure of low-dimensional AlN nanomaterials cannot be precisely controlled.In this paper,a systematic research on the controllable growth and optimization of low-dimensional AlN nanomaterials by plasma enhanced chemical vapor deposition?PECVD?were carried out,the main achievements are summarized as follows:?1?Through structural design and process control,the mutual transformation and controllable growth of three-dimensional AlN films,two-dimensional AlN nanocrystals and one-dimensional AlN nanords are realized.Catalysts play a decisive role in the morphology of low dimensional AlN materials.The quality of low-dimensional AlN nanomaterials is greatly influenced by NH₃ flow,growth temperature and radio-frequency?RF?power.In order to obtain high-quality AlN nanaorods and AlN nanowires,NH₃ flow should be high enough to inhibit the lateral growth of AlN.Growth temperature and RF power both have a significant impact on reaction activation energy and they need match each other.?2?AlN nanosheets with a new structure were found,and their morphology features and growth mechanism were studied in detail,providing a new thought for the growth of high-quality low-dimensional nanostructured materials.The AlN nanosheets can be up to 8 microns in width and are composed of small single crystal AlN nanorods with uniform arrangement and density.The specific surface area of the AlN nanosheets increases obviously,and the controlled growth of single crystal AlN nanorods with large area as well as high consistency in arrangement and orientation was realized indirectly,providing a new thought for the growth of high-quality low-dimensional nanostructured materials.Also,the periodic growth characteristic of the AlN nanosheets was studied in detail,and the cyclic growth mechanism of the AlN nanosheets was revealed.?3?Metal-semiconductor-metal UV detectors based AlN nanosheets were designed and prepared,and effect of the AlN nanosheets with different morphologies on the dark current of the detector was studied.At the bias voltage of 1V and 5V,dark currents of the detector were both nA level,the smallest of which can reach 5.27nA@5v and 0.21nA@1v.Under the same conditions,the dark currents of detectors based the AlN nanosheets were reduced by several orders of magnitude than that of detectors based AlN thin film,reflecting the great advantages of low-dimensional nanostructured materials over thin films or other bulk materials in the field of ultraviolet detectors.To sum up,this paper has realized the controllable growth of low-dimensional AlN nanomaterials and prepared low-dimensional AlN-based ultraviolet detectors,providing a new idea for the preparation of large-area and high-quality low-dimensional nanostructured materials and the improvement of corresponding UV detector performance.