Research On Boron Doped Diamond Films By Chemical Vapor Deposition

Diamond has a unique physical and chemical properties, chemical stability, boron-doped diamond (Boron-doped Diamond BDD) film is not only a semiconductor material with a wide band gap, but also has excellent physical and chemical properties, and thus in electronic devices and optoelectronics the field of application of the device has great potential.In this work, through HFCVD method, we use hydrogen and methane as a reaction gas, and diborane as a boron doped source, the deposition of diamond film in Mo(Re) alloy substrate, the proportion of borane methane, the structural properties of the deposition of diamond films affected. Boron-doped diamond thin film growth on Mo (Re) alloy material meet the need of the requirements of the field emission device, the residual stress state of thin film growth on the surface of the foil material, as well as post-treatment processes to improve the quality of the film, reducing the residual stress are studied, the results show that:(1) Carbon atom diffusioned into Mo (Re) body-centered cubic crystal structure caused by lattice expansion of Mo (Re) alloy substrate prior to deposition of diamond generated the Mo2C brittle transition layer, Re exist in the form of substitutional solid solution;(2) When the the boron carbon volume ratio of V (B2H6)/V (CH4) increased, changes of the grain radius rendered smaller. A small amount of boron doping leads to grain refinement. when the volume ratio up to3%, diamond peaks widen, the low beam drift in the position of the500cm-1and1200cm-1broad appeared, declining in the quality.(3) The resistivity of the diamond film in a low concentration of boron-doped (V (B2H6)/V (CH4)<3%) sharply declined with the increase of the concentration of borane; when the concentration of V (B2H6)/V (CH4)>3%the downward trend of the resistivity of the film decreases.(4) With deposition time increasing, trend of the grain increasing is obvious, when the deposition time to60min, the surface of the film has a large effective electron emission area, the size distribution of the variance is small.(5) With the deposition substrate temperature increasing, the film density increased; as the substrate temperature increased to700℃the grain size distribution is uniform, about0.36±0.03μm, and most of the rendering are (111) plane,rain density up to8.0/μm2. Thermal stress with increasing deposition temperature monotonically increasing. The FWHM with deposition temperature rise decreased after increasing trend; when the deposition temperature is around700℃, the quality is the best with the FWHM14.5cm-1and the compressive stress about2.0GPa in the film.(6) After annealing under hydrogen atmosphere treatment, the thin film of amorphous carbon, graphite component is relatively decreased37.6%, and the film sees a certain degree of improvement.(7) After H2O2(aq) treatment, the relative content of trans-PA film declines from69.0Wt%to73.0Wt%,which shows the enhancement of the film quality, and the thermal stress released.