热丝化学气相沉积法在CH4／H2混合气体中低温生长超薄纳米金刚石膜

用热丝化学气相沉积方法研究了低温(~550℃)和低反应气压(~7 Torr)下硅片上金刚石膜的成核和生长.成核过程中采用2.5%的CH4浓度,在经充分超声波预处理的硅片上获得了高达1.5×1011cm-2的成核密度.随CH4浓度的增加所成膜中的金刚石晶粒尺寸由亚微米转变到纳米级.成功合成了表面粗糙度小于4nm、超薄(厚度小于500nm)和晶粒尺寸小于50nm的纳米金刚石膜.膜与衬底结合牢固.膜从可见光至红外的光吸收系数小于2×104cm-1.用我们常规的HFCVD技术,在低温度和低压下可以生长出表面光滑超薄的纳米金刚石膜.

LOW-TEMPERATURE GROWTH OF ULTRA-THIN NANO-CRYSTALLINE DIAMOND FILMS BY HFCVD IN A CH4/H2 MIXTURE

The diamond nucleation and growth on Si substrate by hot filament chemical vapor deposition (HFCVD) at the low temperature ( ～ 550℃ ) and low pressure ( ～ 7 Torr) were studied. Nucleation density (ND) as high as 1.5 × 1011cm-2 was obtained on well ultrasonically pretreated substrate at the nucleation conditions of 2.5% CH4/H2. Diamond grain sizes change form sub-micron to nano-meter scales with the increase of CH4 concentration. Smooth ultra-thin (thickness ＜500 nm) nano-crystalline diamond (NCD) films with grain sizes less than 50 nm and surface roughness as low as 4nm have been synthesized. The adhesion between the film and substrate is good. The optical absorption coefficient in visible (VIS)to infrared (IR) wavelength range is less than 2 × 104cm-1. Smooth ultra-thin NCD films can be synthesized at low temperature and low pressure by our conventional HFCVD technique.