Excellent crystalline silicon surface passivation by amorphous silicon irrespective of the technique used for chemical vapor deposition

Abstract

Crystalline silicon surface passivation by amorphous silicon deposited by three different chemical vapor deposition (CVD) techniques at low (T∼130 °C) temperatures is compared. For all three techniques, surface recombination velocities (SRVs) are reduced by two orders of magnitude after prolonged thermal annealing at 200 °C. This reduction correlates with a decreased dangling bond density at the amorphous-crystalline interface, indicating that dangling bond saturation is the predominant mechanism. All three deposition methods yield excellent surface passivation. For a-Si:H layers deposited by radio frequency plasma enhanced CVD, we obtain outstanding carrier lifetimes of 10.3 ms, corresponding to SRVs below 1.32 cm/s.