PECVD法制备掺硼纳米金刚石薄膜的工艺研究进展

首先详细介绍了金刚石作为半导体材料的优异性能,然后从应用角度阐述了NCD薄膜掺B后形成半导体材料的优势,接着探讨了影响NCD薄膜性能(电性能、光学性能、生物性能等)的主要工艺条件(包括硼源种类、掺硼浓度、衬底温度、后处理)。研究发现,大多数研究者都采用液态和气态硼源,而固态硼源由于很难液化且浓度不易控制而不常被采用,掺B后NCD薄膜的电阻率急剧下降,紫外波段下透过率可达51%,磁阻效应变好。另外衬底温度对BD-NCD薄膜的质量以及性能都有影响,衬底温度太高,非晶碳含量增加,金刚石质量下降;衬底温度太低,能够进入NCD晶界或晶粒的有效硼原子减少,影响其电学性能、光学性能,在最佳衬底温度工艺下的电导率可达22.3 S/cm,而在电化学性能方面,其电化学窗口可达3.3 V。而选择合适的硼源浓度对BD-NCD的电性能、光学性能、生物性能也非常关键,硼源浓度过大,BD-NCD表面粗糙度和晶粒尺寸增大;硼源浓度过小,产生空穴进行导电的B原子就少,在合适硼源浓度工艺条件下其载流子浓度可达1021 cm-3,折射率可达2.45。还有研究者对BD-NCD薄膜进行后处理工艺(退火、等离子体处理等),发现后处理对其电性能也有一定的影响。因此,选择合适的工艺对生长质量高、性能优异的NCD薄膜尤为重要。最后对BD-NCD薄膜的发展以及后续研究方向进行了展望和期待。

Research Progress in Preparation of Boron Doped Nanocrystalline Diamond Films by PECVD Method

First the excellent performance of diamond as a semiconductor material was introduced in detail in this work, then advantages of B-doped NCD thin films as semiconductor materials were discussed from the point of application. Finally major technological conditions (electrical property, optical property, biological properties, etc.) affecting NCD thin film performance (including source category of Boron, concentration of Boron doping, substrate temperature and aftertreatment) were elaborated. Researches found that liquid and gaseous boron source were used by most researchers. However, solid boron source was seldom used due to difficulty in liquefaction and concentration control. Electrical resistivity of NCD thin films decreased sharply after being doped with B, ultraviolet transmittance could be up to 51% and the magnetoresistance effect became better. In addition, the substrate temperature had effects on both quality and performance of BD-NCD film. Amorphous carbon content increased and quality of diamond decreased if the substrate temperature was too high; effective boron atoms capable of entering NCD grain boundary or grain decreased if the substrate temperature was too low. Both electric properties and optical properties were influenced. Conductivity at optimal substrate temperature could be up to 22.3 S/cm and the electrochemical window could be up to 3.3 V in the aspect of electrochemical properties. The selection of appropriate boron source concentration was crucial for electrical properties, optical properties and biological properties of BD-NCD. If B source concentration was too high, the surface roughness and grain size of BD-NCD increased; if B concentration was too small, the hole produced conductive B atoms decreased. Under suitable boron concentration conditions, the carrier concentration could be 1021 cm-3 and refractive index 2.45. Some researchers applied postprocessing technology (annealing and plasma treatment) to BD-NCD films and found it had some effects on the electric properties. Therefore, selection of an appropriate technology was of great importance to NCD films of high growth quality and excellent performance. Finally, the development of BD-NCD thin films and future research focus were prospected and expected.