Low Temperature Growth of Diamond Films from Vapor Phase

以乙醇和氢气为原料合成金刚石薄膜，以期在尽可能低的温度下合成金刚石薄膜。我们使用了电容耦合射频(13.56 MHz)等离子体CVD设备和外部加热器。在不同的气压、气体浓度、加热温度和电极间距的条件下制备了薄膜。利用拉曼光谱、扫描电子显微镜和电子自旋共振对薄膜进行了表征，得到了以下结果。当使用直径为50 mm的反应管时，如果不加热，金刚石膜不会生长。这是因为仅靠射频放电产生的温度不足以生长金刚石。当电炉将温度设定在550Torr C时，钻石在1-3ﾟ的气体压力和1-3%的乙醇浓度下生长。在上述压力和浓度下，钻石在350-800ﾟC.4的温度下生长。在350ﾟC下生长的薄膜除了含有金刚石外，还含有非金刚石组分。它们是由球状颗粒组成的。当使用直径为35 mm的反应管和红外加热器时，通过优化电极间距可以获得高质量的薄膜。在上述情况下，即使在不加热的情况下也可以获得不含金刚石组分的薄膜。在这种情况下，温度估计为370ﾟC。

The synthesis of diamond films from ethyl alcohol and hydrogen was performed objecting to synthesize them at temperature as low as possible. We used a capacitively coupled rf (13.56 MHz) plasma CVD apparatus and an external heater. The films were prepared at various conditions varying gas pressure, gas concentration, heating temperature and electorode distance. The films were characterized by Raman scattering, SEM and ESR, and the following results were obtained.1. When a reaction tube with a diameter of 50 mm is used, diamond films do not grow if the tube is not heated. This is due to that the temperature produced by only rf discharge is not sufficient for diamond growth.2. When the temperature is set at 550ﾟC by an electric furnace, diamonds grow at gas pressures of 1 - 3 Torr and ethyl alcohol concentrations of 1 - 3 %.3. Under above pressure and concentration, diamonds grow at temperatures of 350 - 800ﾟC.4. The films grown at 350ﾟC contain nondiamond components in addition to diamonds. They are composed of balllike particles.5. When a reaction tube with a diameter of 35 mm and an infrared heater are used, the film of high quality is obtained by optimizing the electrode distance.6. In above case, the film without nondiamond components is obtained even without the heating. The temperature in this case is estimated to be 370ﾟC.