Optimization of ALD AI_2O_3 process parameters for passivation of c-silicon and its implementation on industrial monocrystalline silicon solar cell

摘要

Effect of process parameters on Al2O3 deposited using Atomic Layer Deposition (ALD) for the surface passivation of c-silicon surface has been investigated. Surface passivation properties of Al2O3 have been measured by evaluating the minority carrier lifetime and interface charges at the Si/Al2O3 interface. It has been observed that surface passivation properties of Al2O3 are strongly dependent on process parameters such as substrate temperature, annealing temperature, and thickness of the deposited Al2O3 film. Minority carrier lifetime, effective charge density (Qeff), and interface defect density (Dit) were observed to vary from 180 to 355cm-2 and 1.2x109 to 1.9x1010cm-2, respectively, for various process parameters. Al2O3 film based on the optimized process parameters were then used as a passivation layer in fabricating industrial PERC solar cells. Effect of Al2O3 passivation in PERC solar cells has been demonstrated by comparing the characteristics of the PERC solar cells with that of the standard Al BSF solar cells. An efficiency improvement of approximate to 0.8% has been observed in passivated emitter rear cells (PERC) solar cells as compared to the standard aluminum back surface field (Al BSF) solar cells.