• The Performance of CVD Diamond
  • Performance
    Owing to the diamond structure, diamond has many excellent performances in many fields such as optics, mechanics, thermal, chemistry and other aspects. Parameters are shown in the following table.
    The Table Of Diamond Capabilities
    Physical Property Nature Diamond High Quality CVD Diamond Polycrystalline Film
    Hardness (kgf/cm2) 10000 9000~10000
    Young's Module (GPa) 1200 Approach to nature diamond
    Coefficient of Friction 0.1 0.1
    Coefficient of Thermal Expansion (10-6/℃) 0.8 0.8
    Thermal Conductivity (300k,w/cm.k) 20 10~20
    Longitudinal Wave Velocity of Sound (m/s) 18000  
    Density (g/cm3) 3.6 2.8~3.5
    Refractive Index (590nm) 2.41 2.4
    Width of Band Gap (eV) 5.5 5.5
    Light Transmission 225nm to far-IR Approach to nature diamond
    Resistivity (Ω.cm) 1016 >1010
    Dielectric Strength (v/cm) 1017 >1018
    Electron Mobility (cm2/v.s) 2200 4500
    Hole Mobility (cm2/v.s) 1600 2300
    Dielectric Constant 5.5 5.5
    Saturated Electron Velocity (cm/s) 2.7X107  

    • At the aspect of optics, the width of diamond band gap is 5.5V. It has appropriate optic refractive index(≈2.4)and less absorption coefficient from 225nm to far-IR wave band(for example, the absolute absorption coefficient of optic CVD diamond is 0.07-0.029cm-1 when the the wavelength is 10.6μm and the thickness is 0.5-1.5mm).
    • At the aspect of mechanism property, the hardness of diamond is about 90GPa. Young's module is 1050GPa. Condensability is 1.7×10-7cm2/kg and the longitudinal wave velocity of sound is about 18000m/s. Thereinto, young's module is the maximal value among all current synthesized materials. Moreover, the coefficient of kinetic friction is only 0.05, which is as little as that of tetrafluoroethylene.
    • Diamond has the highest thermal conductivity that can be 20w/cm.k at 300k. At the room temperature, the coefficient of thermal expansion is 0.8×10-8/k and the thermal conductivity of diamond is 5 times than that of copper. the melting point and boiling point are 3500℃ and 4200℃ respectively.
    • The hall hole mobility of nature diamond is 1800cm2/v.s and the electron mobility is 2000cm2/v.s. the excursion velocity of hole and electron carrier will be saturated when the electric-field intensity reach to 104v/cm. the saturation of hole and electron are 107cm/s and 2.0×107cm/s respectively. the resistivity is 1015Ω.cm. the hole mobility of artificially synthesized diamond can reach 1400 cm2/v.s. especially synthesized diamond films have the negative electron affinity(NEA) and show excellent Field Emission performance which is affected by the dopant, surface roughness of the film, measure scale and the like. According to the study, nano diamond will enhance the field emission performance.
    • In the area of chemical property, the diamond does not react with ordinary acid when the temperature rises; it also shows stability in the thermal chromic acid or the mixed acid of sulfuric acid and nitrate acid. However, under high temperature diamond is easy to be oxidated and reacts with some metals to form carbides, such as tungsten, titanium, and zirconium. Otherwise it will be decomposed after reacting with iron, cobalt, nickel, anganese and so on.