Research On The Plasma Immersion Ion Inplantation SYstem And Its Application

Plasma immersion ion implantation (PⅢ for short) is one of the most common methods to modify surface properties. During the PⅢ processing, ions are accelerated and injected into workpiece under negative bias voltage, the surface properties are modified by changing the component of the elements and the structures. In this dissertation, PⅢ are firstly used to produce black silicon, and black silicon solar cells based on these materials are produced successfully.The main contact of this dissertation is summed up as follows:■The research on the system of ICP PⅢ1. PⅢ injection model is studied systemly. The requirement for design the parts of the systems are given by investigateing the sheath, inject model and child sheath inject model.2. The three dominant parts, including processing chamber, rf power system and bias voltage system are investigated and design. A PⅢ system is set up successfully. The basic plasma characterization, such as ion density, plasma potential, are investigated by varying processing parameters, such as RF power, working pressure. The phenomenon of CCP in low RF power region is also investigated in this dissertation.■The application of PⅢ system1. The study on the black silicon produced by PⅢ:black silicon is firstly produced using PⅢ process. The infunce of the processing parameters on the surface morphology are studied systemly and kinds of structured black silicon are controlly produced, including needle-like structure, porous-like structure, mountain-like structure, moth-eye-like structure, pyramid-like/inversted pyramid-like structure, micro/nano dual-scale structure and so on. The optical property, electrical property and wetting property of black silicon are investigated, results show that the average reflectance of black silicon can be reduce to as low as1%, ion damage account for the low minority lifetime of the black silicon and black silicon own a good hydrophobicity. The formation mechanism of black silicon by using PⅢ is given in the end.2. The investigation of black silicon solar cells:the conventional wet textured method was replaced by the PⅢ textured black silicon. The single crystalline silicon solar cells with coversion efficiency of17.5%were produced successfully, while the average coversion efficiency of multi-crystalline silicon solar cells was16.8%. Both of them are about0.5%higher than that of the conventional solar cells. The sheet resistance, minority lifetime, silicon nitride-silicon interface, Ag-Si interface, and quantum efficiency of balck silicon solar cells are invertigated, respectively. The conversion efficiency of the black silicon solar cells would be futher increased by optimizing the following-up processes.3. The investigation of the pn junction produced by PⅢ:The requirements of the high efficiency crystalline solar cells are shallow junction and high sheet resistance. P and B elements were injected into silicon substrate using PⅢ processing and the pn junctions with depths less than100nm and surface concentration less than5×1020cm-3. Injected elements were actived and the damaged were restoration with annealing on the temperature of1050℃in10s, the sheet resistance of the pn junctions varied in the region of80to150Ω/□.