常规与纳米金刚石薄膜介电性能的比较

Comparison of Dielectric Properties between Conventional and Nanocrystalline Diamond Films

用热丝CVD方法制备了常规和纳米金刚石薄膜。测量了其电阻率、介电常数和损耗角正切值。实验结果表明 ,常规金刚石薄膜的电导率、损耗角正切值均小于纳米金刚石薄膜 ,介电性能比较理想。两种薄膜的介电常数基本相同 ,损耗角正切值在1 0 5 Hz处都有弛豫极大值 ,表明在该频率范围内 ,主要为弛豫损耗机制。

Conventional and nanocrystalline diamond films were prepared using HFCVD.Their resistivities,dielectric constants and dielectric loss tangents were measured and compared.The results show that the conventional film has better dielectric properties.Its resistivity varies from 1.5×10 14 Ω·cm to 1.2×10 10 Ω·cm in the range of room temperature to 573K and its dielectric loss tangent is between 0.014 and 0.049 in the 70k 25MHz frequency range.Under the same measurement conditions the resistivity of the nanocrystalline film is 2×10 7Ω·cm to 6×10 4Ω·cm and the dielectric loss tangent of the nanocrystalline film is between 0.056 and 0.174.The dielectric constants of both films are close.There is a maximum dielectric loss tangent at about 10 5Hz for both films,which indicates that relaxation process is the main loss mechanism in that frequency range.The conductivity and dielectric loss tangent are probably related to the defects and non diamond phases along the grain boundaries.