Excellent surface passivation of silicon at low cost: Atomic layer deposited aluminium oxide from solar grade TMA

In this work, we investigated the surface passivation performance of thermal atomic layer deposited Al₂O₃ films using two different grades of trimethylaluminum (TMA). All films were grown on the InPassion Lab tool from SoLayTec. We demonstrate that the surface passivation quality is not compromised by the higher impurity concentration in the cheaper solar grade TMA. Excellent passivation on both p- and n-type silicon surfaces was obtained in a wide process window for samples deposited using both grades of TMA. Remarkably, even a better passivation quality was obtained by the solar grade TMA, especially on n-type samples. It is therefore demonstrated that excellent surface passivation by ALD Al₂O₃ films can be realized using a lower cost precursor.