Diamond nucleation improved by negative bias-enhanced technology on Si (100) substrate has been investigated on a microwave plasma enhanced chemical vapor deposition (MPCVD) apparatus using a gas mixture of methane and hydrogen. The results show that the bias voltage has a significant effect on the uniformity of the nucleation density and the concentration of the methane mainly relevant to the nucleation time. There is an obvious brim effect of the nucleation when the size of the silicon substrate is less than that of the Mo substrate holder. The nucleation density of the side is higher than that of the center on the substrate when the bias voltage is lower than -150 V. The nucleation density of the side decrease significantly with the bias voltage when the bias voltage is lower than -150 V. There are nearly no nuclei on the side of silicon when the bias voltage is -200 V. This effect may be contributed to the electron emission of the diamond on Mo substrate holder. The concentration of the methane has little effect on the nucleation density at a fixed bias voltage. Increasing the methane concentration is useful for decreasing the nucleation time.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |