The Research On The Semiconductor Characteristic And Electroluminescence Phenomenon Of C-BN Crystal

The cube boron nitride crystal(c-BN)is another new ultra hard material which the humanity gets by the high temperature pressure technique synthesis after the artificial diamond.It is the typicalâ…¢-â…¤races nitride,has the sphalerite structure,and the macroscopic symmetry belongs to the group^(?)3m. It has the outstanding physical chemistry performance,besides the chemical stability surpasses the diamond and the degree of hardness is inferior to diamond,it has wide energy gap(about 6.4eV),the low coefficient of dielectric loss,the heat conductivity as high as 13W/cm.K theoretically (experiment to obtain maximum heat conductivity 7.4W/cm.K),and the possibility to be doped p and n forms semiconducting material and so on causes it is applied to many domains,especially photoelectric apparatus,high temperature component,microwave device etc.Therefore,the research regarding the c-BN semiconductor characteristic has the very vital significance.But as a result of the c-BN material size to measuring technique's limit,this aspect's related reports are not many.This paper carries on a research to the semi-conductor characteristic of square Boron Nitride in the theories and experimentation.First,calculate the band-gap structure using the GGA method(gradient correction Local Density Functional Theory)of the first-principle methods;get the density of electronic state and the density of electron number with the direction of(100),(110)and (111).For the experienced result of the partial negative energy calculated based on the density functional method,we correct it with experimental result of ultraviolet absorption spectrum,we get the result of 6.3eV with the error of 0.1eV.The non-direct band gap energy band structure theory laid the foundation for the research of electroluminescence.Secondly,study on the c-BN conductivity by using of basic j-E relation experimental,and with its characteristic electrolyte,raise the two-phase model of the breakdown voltage. Meanwhile,the several orders of magnitude current peaks of the conductivity properties have been found after the process of a typical semiconductor temperature characteristic by research about the c-BN conductivity of the temperature dependence.Through the research of the Hall characteristics and the heat shock current spectrum,found impurity level in the 0.56eV under the conduction band,analysts believe that it is induced by the defect in the material synthesis.In this paper,we find that when the strength of electric field was up to 4.8×10⁶V/cm,the current become instable,and if the strength of electric field was increased continually,there would be a electric breakdown.After the electric breakdown,the conductivity of c-BN will be too great,and when the strength of electric field increased to 10²V/cm,the current density would be up to 10A/cm²,accompanied by strong radio luminescence.At the same time, the temperature of the materials was increased rapidly;and the loop current oscillates at the periodicity of some nanosecond,the measurement results show that was the pulsed light.According to this phenomenon,using of the theory of band gap luminescence and dielectric breakdown,we give the basic theoretical model to explain the luminescence mechanism.In this paper,the theoretical and experimental result is of great significance,for it is the basic work for deeply research of c-BN semiconductor devices,ultraviolet laser and detector.