Influence of the Oxidant on the Chemical and Field-Effect Passivation of Si by ALD Al[sub 2]O[sub 3]

Dingemans, G Gijs; Terlinden, NM Nick; Pierreux, Dieter; Profijt, HB Harald; Sanden, van de Mcm Richard; Kessels, Wmm Erwin

doi:10.1149/1.3501970

Cited by 162 publications

(150 citation statements)

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“…Thus it is concluded that a large part of the improvement in passivation occurring after thermal treatment of ALD deposited alumina originates from increasing the concentration of negative charge in the films. This is in agreement with previous ALD Al2O3 work performed in flat silicon [36]. For pyramidal surfaces, however, lower passivation quality is observed with respect to hybrid and SiNW surfaces.…”

Section: Interface Recombinationsupporting

confidence: 92%

Passivation of all-angle black surfaces for silicon solar cells

Rahman

Bonilla

Nawabjan

et al. 2017

Solar Energy Materials and Solar Cells

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Abstract-Optical losses at the front surface of a silicon solar cell have a significant impact on efficiency, and as such, efforts to reduce reflection are necessary. In this work, a method to fabricate and passivate nanowire-pyramid hybrid structures formed on a silicon surface via wet chemical processing is presented. These high surface area structures can be utilised on the front surface of back contact silicon solar cells to maximise light absorption therein. Hemispherical reflectivity under varying incident angles is measured to study the optical enhancement conferred by these structures. The significant reduction in reflectivity (<2%) under low incident angles is maintained at high angles by the hybrid textured surface compared to surfaces textured with nanowires or pyramids alone. Finite Difference Time Domain simulations of these dual micro-nanoscale surfaces under varying angles supports the experimental results. In order to translate the optical benefit of these high surface area structures into improvements in device efficiency, they must also be well passivated. To this end, atomic layer deposition of alumina is used to reduce surface recombination velocities of these ultra-black silicon surfaces to below 30 cm/s. A decomposition of the passivation components is performed using capacitance-voltage and Kelvin Probe measurements. Finally, device simulations show power conversion efficiencies exceeding 21% are possible when using these ultra-black Si surfaces for the front surface of back contact silicon solar cells.

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Section: Interface Recombinationsupporting

confidence: 92%

Passivation of all-angle black surfaces for silicon solar cells

Rahman

Bonilla

Nawabjan

et al. 2017

Solar Energy Materials and Solar Cells

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“…However, on p-type Si, the SiO x / SiN x stack was clearly superior to the single layer SiN x . The level of passivation induced by atomic layer deposited ͑ALD͒ Al 2 O 3 , containing Ͼ5 ϫ 10 12 cm −2 negative charges, 16 was higher, but not substantially so, than that for the stacks, as shown in Fig. 1.…”

mentioning

confidence: 78%

“…Furthermore, the thermal stability ͑up to 850°C͒ of the stack was found to be very high, which can be ascribed to effective hydrogenation of the Si/ SiO x interface under influence of the SiN x layer. The results presented are especially timely because various lowtemperature passivation schemes, such as aluminum oxide ͑Al 2 O 3 ͒, [14][15][16] are currently under evaluation as replacements for the standard aluminum back surface field in solar cells with thinner Si wafers.…”

mentioning

confidence: 99%

Effective passivation of Si surfaces by plasma deposited SiOx/a-SiNx:H stacks

Dingemans

Mandoc

Bordihn

et al. 2011

Applied Physics Letters

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Very low surface recombination velocities <6 and <11 cm/s were obtained for SiOx/a-SiNx:H stacks synthesized by plasma-enhanced chemical vapor deposition on low resistivity n- and p-type c-Si, respectively. The stacks induced a constant effective lifetime under low illumination, comparable to Al2O3 on p-type Si. Compared to single layer a-SiNx:H, a lower positive fixed charge density was revealed by second-harmonic generation measurements, while field-effect passivation was absent for a reference stack comprising thermally grown SiO2. The results indicate that hydrogenation of interface states played a key role in the passivation and remained effective up to annealing temperatures >800 °C.

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“…It has been reported by Dingemans et al [13] and Terlinden et al [28] that those stacks exhibit excellent chemical passivation levels (e.g., D it values o 10 11 eV À 1 cm À 2 at mid gap [32]), while their Q f can effectively be tuned from strongly negative up to zero or even positive values by carefully tuning the ALD SiO 2 thickness. It is hypothesized that for these stacks the SiO 2 interlayer acts as a (trap-assisted) electron tunnel barrier, preventing charge-injection from the c-Si base into the electron trap sites in the Al 2 O 3 [13,28].…”

Section: Introductionmentioning

confidence: 99%