The Characterization Of Hollow Cathode Discharge And Its Application Of The Microcrystalline Silicon Deposition

With the rapid development of the society and economy, the energy structure should be changed and the new energy sources with advantages such as renewable, pollution-free, low cost were required. Solar cell is one of new ideal sources of energy based on transformation of the solar energy into electric power, in which microcrystalline silicon film (μc-Si) solar cell is dramatically researching one because of its high efficiency and inexpensive.In this thesis, we developed a new method to prepare microcrystalline silicon film with controllable crystal rate based on hollow cathode discharge plasma enhanced chemical vapor deposition process. Here SiH₂Cl₂ was used as precursor gas and H₂ was used as reductive gas. It is noticed that the crystallization rate of films was dependent on the deposition conditions. The results are concluded as:(1) The design of the plasma setup. These include the design and fabrication of the hollow cathodes, the gas flow path and the chamber. Two kinds of hollow cathode electrodes, the aluminum cathodes with hollows in diameter of 5mm and the stainless steel cathodes with hollows in diameter of 3mm were fabricated. The gas flow path for the purpose of atomic layer deposition process was build up. It can run automatically by PLC control system. At last the system of the equipment setup worked well and met all the requirement of the experiment.(2) The characterization of hollow cathode discharge. The direct current (DC) power source, pulsed DC power source and radio frequency (RF 27.12MHz) power source were adopted to generate plasma. The I-V curves of the hollow cathode discharge at DC power and pulsed DC power demonstrated the typical hollow cathode discharge configurations. According to the experimental results, the hollow cathode discharge provides higher efficiency than that in plane electrode system. The results of Langmuir probe in RF power hollow cathode discharge (RF-HCD) show that a highest electronic density of 100×1010cm-3 can be achieved in this condition, much higher than that in the plane electrode system, by two orders of magnitude exactly. But the electronic temperature remains almost identical.(3) The deposition of microcrystalline silicon films. The several factors influenced the film structure and morphology, such as the ratio of the gas flow rate, the RF power, temperature of the substrate holder, the working pressure, diluted Ar gas were investigated in this work. When the microcrystalline silicon film was deposited at gas ratio of SiH₂Cl₂/H₂=3/200sccm, 80W of RF power, 200³00℃of temperature, and the working pressure of 200³00Pa,a crystallization rate of 71.4% can be achieved. According to the results of surface morphology measurement, it shows that the films were grown in island model, and the size of the grain and thickness of the films will be grown along with the increase of the input power.