Silicon surface passivation by atomic layer deposited Al2O3

Abstract

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

“…1,2 The field effect passivation associated with the negative fixed charges near the Al 2 O 3 / c-Si interface, 2 proved to be especially beneficial for the passivation of highly doped p-type c-Si, with Al 2 O 3 even outperforming thermally grown SiO 2 . 3 The application of a thin Al 2 O 3 film as a front passivation layer on a B-doped emitter has recently led to efficiencies as high as 23.2% for n-type c-Si solar cells.…”

Effect of low thermal budget annealing on surface passivation of silicon by ALD based aluminum oxide films

“…This trend is observed in all the samples. Therefore, optimized sintering time for the best passivation is 105 s. It is to be noted that in most of the publications, 1,[7][8][9][10]27 annealing is done for longer time durations (10-30 min) and there is hardly any publication for shorter t anl . Table 2 summarizes the measured minority carrier lifetime and corresponding estimated SRV values with films of different thicknesses.…”

“…2 Passivation reduces surface recombination losses by two ways, i.e., chemical passivation (reduction of the density of electronic surface states) and field effect passivation (the presence of fixed charges in the dielectric layer over the silicon surface that reduces the carrier density underneath the interface of the two). 1,[7][8][9][10] A well passivated surface reduces the recombination of photo-generated carriers in the vicinity of the two surfaces and improves the cell performance parameters. [11][12][13][14] Thermally grown silicon oxide (SiO 2 ), silicon nitride (a-SiN x :H) and amorphous silicon (a-Si:H) are commonly used for surface passivation of c-Si solar cells.…”

“…[15][16][17][18][19][20][21] Aluminum oxide (Al 2 O 3 ), a dielectric, has excellent surface passivation properties on c-Si of both conductivity type materials. [7][8][9] Recently Al 2 O 3 films have been used to passivate the silicon surface to achieve high efficiency solar cells. [11][12][13][14] There are several methods for Al 2 O 3 film deposition, e.g., sputtering, 22 atmospheric pressure chemical vapor deposition, 23 RF magnetron sputtering 24 and plasma enhanced chemical vapour deposition, 25,26 etc.…”

“…Although in some papers, low SRV is obtained in as-deposited Al 2 O 3 films, 28 however, high quality surface passivation is realized after post deposition annealing. 1,[7][8][9] Normally 30 min post-deposition annealing at 400 1C is required to get good surface passivation. To the best of our knowledge, low thermal budget annealing is very scantly reported in the literature.…”