Passivation study of aluminium oxide deposited by atomic layer deposition

In the recent years, it was reported that surface passivation of crystalline solar cell with aluminum oxide (Al2O3) deposited by atomic layer deposition (ALD) seems to be a good candidate for c-Si Solar cells for both n-type and p-type Si due to its very high negative fixed charge density (Qf ~ 1012-1013 cm-2) . This paper assesses the study of passivation quality of different dielectrics. We have considered three different dielectric materials for this work namely: thermal SiO2(20nm), SiO2 deposited by plasma enhanced chemical vapor deposition (PECVD)(20nm), Al2O3 deposited by ALD with two different techniques (thermal(20nm) and plasma(15nm)). MOS-capacitors has been fabricated and characterized to extract the interface trap charge densities (Dit) at the silicon/dielectric interface, fixed charge (Qf) in the dielectric and life time measurements were also performed with quasi-steady-state photo-conductance decay , transient techniques .