Stability of Al2O3 and Al2O3/a-SiNx:H stacks for surface passivation of crystalline silicon

Abstract

The thermal and ultraviolet (UV) stability of crystalline silicon (c-Si) surface passivation provided by atomic layer deposited Al2O3 was compared with results for thermal SiO2. For Al2O3 and Al2O3/a-SiNx:H stacks on 2 Ω cm n-type c-Si, ultralow surface recombination velocities of Seff<3 cm/s were obtained and the passivation proved sufficiently stable (Seff<14 cm/s) against a high temperature “firing” process (>800 °C) used for screen printed c-Si solar cells. Effusion measurements revealed the loss of hydrogen and oxygen during firing through the detection of H2 and H2O. Al2O3 also demonstrated UV stability with the surface passivation improving during UV irradiation.

Er3+ and Si luminescence of atomic layer deposited Er-doped Al2O3 thin films on Si(100)

“…The trends of the Si PL signal and S eff were qualitatively in good agreement: S eff decreased by annealing at moderate temperatures, whereas higher temperatures led to a degradation of the passivation performance. 29,37 The effective lifetime of $ 6 ls measured after annealing at 1000 C was similar to that obtained for an unpassivated Si …”

“…Note that the presence of a significant density of CO x groups in the bulk of the material would also not be expected for ALD with H 2 O as the oxidant, in contrast to plasma ALD where C-O vibrations were detected by infrared absorption spectroscopy. 33,37,42 On the other hand, it is likely that the CH x feature at 740 C can be attributed to the removal of carbon impurities that originate from the precursor and were incorporated into the Al 2 O 3 :Er film during deposition. Maxima in the effusion transients were observed at 700 C for both H 2 O and H 2 .…”

Recent Developments on Silicon Based Solar Cell Technologies and their Industrial Applications

“…These results are comparable to the solar cells employing thermal oxide as used in record-efficiency solar cells [39]. Al 2 O 3 layer also demonstrated a better UV stability than thermal SiO 2 with the surface passivation improving during UV irradiation [41].…”

Blistering Induced Degradation of Thermal Stability Al2O3Passivation Layer in Crystal Si Solar Cells

“…Al 2 O 3 film grown by atomic layer deposition (ALD) has demonstrated excellent uniformity and growth control, suggesting better passivation quality [1]. Al 2 O 3 synthesized by ALD provides a high quality surface because its low interface state density provides good chemical passivation and the negative fixed charges near the interface for p-type c-Si provide excellent field-effect passivation [2][3][4][5][6]. Al 2 O 3 film also can offer excellent dielectric properties [7].…”