| As a fourth-generation semiconductor material,diamond has the characteristics of high carrier mobility,high thermal conductivity,low dielectric coefficient,wide band gap,high hardness,etc.,and has important applications in optics,electricity,mechanics and other fields.High-purity diamond has high resistivity at room temperature.In order to realize the semiconductor application of diamond,impurities must be introduced to make it have semiconductor properties.At present,compound diamond semiconductors formed by atomic-level bonding have been developed abroad,which can provide higher power,higher frequency,smaller and more energy-saving electronic devices for communications,radar,photodetectors,sensors and other fields.Based on the research group’s years of research on the preparation of homoepitaxial single crystal diamond,and according to the material’s microstructure design theory,this paper proposes to construct a composite diamond semiconductor material.Diamond composites constructed by introducing artificial primitives often have unique properties:the magnetic element iron is introduced during the preparation of diamond,and the possible magnetic and electrical properties are investigated.By preparing diamond on different substrates such as non-metals,metals,oxides,etc.,new physical properties that may arise in diamond composites are investigated due to the structure of the substrate material,carbonization caused by plasma activity,solubility in diamond,etc.Finally,the preparation,growth mechanism and special physical properties of the constructed diamond composites are systematically summarized.The specific research contents are as follows:1.Growth of diamond films on silicon substrates and preparation of diamond-based dilute magnetic semiconductors.Micro-diamond and nano-diamond films were grown on silicon substrates,and the surface morphology and structure of diamond films at different deposition times were studied by AFM,XRD and Raman spectroscopy.The introduction of magnetic element iron into diamond was achieved through equipment modification.Overcoming the low solubility of iron in diamond,the preparation of dilute magnetic semiconductor is completed.The optical absorption spectrum shows that its band gap is1.65 e V,and the magnetic measurement results show that the magnetic transition temperature from paramagnetic to ferromagnetic is higher than room temperature,which is the first time to obtain a diamond-based dilute magnetic semiconductor with both semiconducting properties and magnetic properties at room temperature.2.The growth and photocatalytic properties of diamond thin films on metal substrates.The growth of diamond was completed on two substrates of molybdenum and tantalum,and the diamond film prepared on the tantalum substrate had a larger grain size.In the process of forming the diamond,the highly active carbon-containing plasma reacts with the two substrates to form a carbide transition layer,which better bonds the diamond and the metal substrate together.The residual stress study of the thin film found that the residual stress decreased with the increase of growth time,and the diamond thin film on the tantalum substrate had smaller residual stress.The diamond films on both substrates have semiconductor photocatalytic properties,and the diamond films on the tantalum substrate have stronger photocatalytic activity,showing a trend of increasing with the thickness of the films.3.Growth and photocatalytic properties of diamond films on oxide substrates.Exploring the preparation and properties of diamond on alumina and potassium tantalum niobate substrates,XRD and Raman spectroscopy show that diamond films on potassium tantalum niobate substrates have higher crystalline quality.And the quality of the diamond film increases with the increase of deposition time.Diamond films prepared on both substrates exhibit photocatalytic properties.Compared with the alumina substrate,the potassium tantalum niobate substrate is more suitable for the preparation of the diamond film and has higher photocatalytic activity,and the photocatalytic performance becomes stronger as the quality of the diamond film increases. |
