Thermal stability investigations of PECVD Al2O3 films discussing a possibility of improving surface passivation by re-hydrogenation after high temperature processes

This work investigates the changing passivation behavior of Al2O3 after different thermal treatments based on carrier lifetime ( eff), interface defect density (Dit) and fixed charge density (Qtot) measurements. A concept of diffusing H species into the dehydrogenated Al2O3 films, termed as re-hydrogenation, has also been investigated for the PECVD deposited Al2O3 samples. Use of a-SiNx:H as a capping layer as in Al2O3/a-SiNx:H stack provides a better thermal stability for a thin PECVD Al2O3 layer. A comparison between single Al2O3 layer and Al2O3/ a-SiNx:H passivation stack after high temperature processes has been also performed in this work.