A review of Al2O3 as surface passivation material with relevant process technologies on c-Si solar cell

Abstract

Surface recombination loss limits the efficiency of crystalline silicon (c-Si) solar cell and effective passivation is inevitable in order to reduce the recombination loss. In this article, we have reviewed the prospects of aluminium oxide (Al2O3) as surface passivation material and associated process technologies are also addressed. Its underlined negative fixed charges, high process stability and process feasibility to use it in ultrathin films, make it exciting one as surface passivation material. Other materials used for passivation and their limitations are addressed. Relevant deposition techniques and their aspects are also discussed here. Ultrathin Al2O3 is generally produced by conventional Atomic Layer Deposition (ALD) methods. But slow deposition rate and low throughput made the ALD process limited its application in commercial solar industry. Plasma Enhanced Chemical Vapour Deposition (PECVD) is also used as alternative one but it suffers from high temperature process stability. Al2O3 deposited by Radio Frequency (RF) sputtering is found out to be one of the best deposition techniques because of its low cost and higher deposition rate.