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Investigation on the passivated Si/Al2O3 interface fabricated by non-vacuum spatial atomic layer deposition system.

Lien SY, Yang CH, Wu KC, Kung CY - Nanoscale Res Lett (2015)

Bottom Line: Thin stoichiometric silicon dioxide films prepared on the Si surface prior to Al2O3 fabrication effectively reduce a considerable amount of blisters.Eventually, the entire PERC with the improved triple-layer SiO2/Al2O3/SiNx:H stacked passivation film has an obvious gain in open-circuit voltage (V oc) and short-circuit current (J sc) because of the increased minority carrier lifetime and internal rear-side reflectance, respectively.The electrical performance of the optimized PERC with the V oc of 0.647 V, J sc of 38.2 mA/cm(2), fill factor of 0.776, and the efficiency of 19.18% can be achieved.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, DaYeh University, No. 168, Xuefu Road, Changhua, 515 Taiwan.

ABSTRACT
Currently, aluminum oxide stacked with silicon nitride (Al2O3/SiNx:H) is a promising rear passivation material for high-efficiency P-type passivated emitter and rear cell (PERC). It has been indicated that atomic layer deposition system (ALD) is much more suitable to prepare high-quality Al2O3 films than plasma-enhanced chemical vapor deposition system and other process techniques. In this study, an ultrafast, non-vacuum spatial ALD with the deposition rate of around 10 nm/min, developed by our group, is hired to deposit Al2O3 films. Upon post-annealing for the Al2O3 films, the unwanted delamination, regarded as blisters, was found by an optical microscope. This may lead to a worse contact within the Si/Al2O3 interface, deteriorating the passivation quality. Thin stoichiometric silicon dioxide films prepared on the Si surface prior to Al2O3 fabrication effectively reduce a considerable amount of blisters. The residual blisters can be further out-gassed when the Al2O3 films are thinned to 8 nm and annealed above 650°C. Eventually, the entire PERC with the improved triple-layer SiO2/Al2O3/SiNx:H stacked passivation film has an obvious gain in open-circuit voltage (V oc) and short-circuit current (J sc) because of the increased minority carrier lifetime and internal rear-side reflectance, respectively. The electrical performance of the optimized PERC with the V oc of 0.647 V, J sc of 38.2 mA/cm(2), fill factor of 0.776, and the efficiency of 19.18% can be achieved.

No MeSH data available.


Related in: MedlinePlus

HR-SEM images for various cycles of deposition and deposition rate of non-vacuum spatial ALD. (a) HR-SEM images for various cycles of deposition of Al2O3 films including 50, 200, 300, and 400 cycles and (b) deposition rate of non-vacuum spatial ALD. This figure can verify the basic characteristic of deposition rate for a self-developed non-vacuum spatial ALD. The image also shows the uniformity of the Al2O3 films, revealing its reproducibility.
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Fig2: HR-SEM images for various cycles of deposition and deposition rate of non-vacuum spatial ALD. (a) HR-SEM images for various cycles of deposition of Al2O3 films including 50, 200, 300, and 400 cycles and (b) deposition rate of non-vacuum spatial ALD. This figure can verify the basic characteristic of deposition rate for a self-developed non-vacuum spatial ALD. The image also shows the uniformity of the Al2O3 films, revealing its reproducibility.

Mentions: Figure 2a shows the HR-SEM images for various cycles of deposition of the Al2O3 films including 50, 100, 300, and 400 cycles. The regime marked by a double-sided arrow is the Al2O3 film. The aim of capping the SiNx film on the Al2O3 film is to discriminate each layer to be observed clearly. From this figure, it can be seen that under different deposition cycles, all the Al2O3 films are uniform without any rough morphology on the surface, revealing the feasibility and reproducibility of this ALD system. Thicknesses of 10.3, 34.8, 48.8, and 62.6 nm correspond to 50, 200, 300, and 400 cycles, respectively. The ALD process allows the deposition of Al2O3 films with an accurate thickness control is demonstrated in Figure 2b. It is shown that the Al2O3 film thickness scales near linear with the number of ALD cycles for our non-vacuum spatial ALD. The slope in Figure 2b is defined as growth per cycle (GPC). The GPC here is around 0.16 nm/cycle, 1 s per cycle, so that the deposition rate is around 10 nm/min. Compared to traditional plasma-enhanced ALD and thermal ALD, the deposition rate of 10 nm/min is much faster, displaying its high potential for being used in the industrials.Figure 2


Investigation on the passivated Si/Al2O3 interface fabricated by non-vacuum spatial atomic layer deposition system.

Lien SY, Yang CH, Wu KC, Kung CY - Nanoscale Res Lett (2015)

HR-SEM images for various cycles of deposition and deposition rate of non-vacuum spatial ALD. (a) HR-SEM images for various cycles of deposition of Al2O3 films including 50, 200, 300, and 400 cycles and (b) deposition rate of non-vacuum spatial ALD. This figure can verify the basic characteristic of deposition rate for a self-developed non-vacuum spatial ALD. The image also shows the uniformity of the Al2O3 films, revealing its reproducibility.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
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Fig2: HR-SEM images for various cycles of deposition and deposition rate of non-vacuum spatial ALD. (a) HR-SEM images for various cycles of deposition of Al2O3 films including 50, 200, 300, and 400 cycles and (b) deposition rate of non-vacuum spatial ALD. This figure can verify the basic characteristic of deposition rate for a self-developed non-vacuum spatial ALD. The image also shows the uniformity of the Al2O3 films, revealing its reproducibility.
Mentions: Figure 2a shows the HR-SEM images for various cycles of deposition of the Al2O3 films including 50, 100, 300, and 400 cycles. The regime marked by a double-sided arrow is the Al2O3 film. The aim of capping the SiNx film on the Al2O3 film is to discriminate each layer to be observed clearly. From this figure, it can be seen that under different deposition cycles, all the Al2O3 films are uniform without any rough morphology on the surface, revealing the feasibility and reproducibility of this ALD system. Thicknesses of 10.3, 34.8, 48.8, and 62.6 nm correspond to 50, 200, 300, and 400 cycles, respectively. The ALD process allows the deposition of Al2O3 films with an accurate thickness control is demonstrated in Figure 2b. It is shown that the Al2O3 film thickness scales near linear with the number of ALD cycles for our non-vacuum spatial ALD. The slope in Figure 2b is defined as growth per cycle (GPC). The GPC here is around 0.16 nm/cycle, 1 s per cycle, so that the deposition rate is around 10 nm/min. Compared to traditional plasma-enhanced ALD and thermal ALD, the deposition rate of 10 nm/min is much faster, displaying its high potential for being used in the industrials.Figure 2

Bottom Line: Thin stoichiometric silicon dioxide films prepared on the Si surface prior to Al2O3 fabrication effectively reduce a considerable amount of blisters.Eventually, the entire PERC with the improved triple-layer SiO2/Al2O3/SiNx:H stacked passivation film has an obvious gain in open-circuit voltage (V oc) and short-circuit current (J sc) because of the increased minority carrier lifetime and internal rear-side reflectance, respectively.The electrical performance of the optimized PERC with the V oc of 0.647 V, J sc of 38.2 mA/cm(2), fill factor of 0.776, and the efficiency of 19.18% can be achieved.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, DaYeh University, No. 168, Xuefu Road, Changhua, 515 Taiwan.

ABSTRACT
Currently, aluminum oxide stacked with silicon nitride (Al2O3/SiNx:H) is a promising rear passivation material for high-efficiency P-type passivated emitter and rear cell (PERC). It has been indicated that atomic layer deposition system (ALD) is much more suitable to prepare high-quality Al2O3 films than plasma-enhanced chemical vapor deposition system and other process techniques. In this study, an ultrafast, non-vacuum spatial ALD with the deposition rate of around 10 nm/min, developed by our group, is hired to deposit Al2O3 films. Upon post-annealing for the Al2O3 films, the unwanted delamination, regarded as blisters, was found by an optical microscope. This may lead to a worse contact within the Si/Al2O3 interface, deteriorating the passivation quality. Thin stoichiometric silicon dioxide films prepared on the Si surface prior to Al2O3 fabrication effectively reduce a considerable amount of blisters. The residual blisters can be further out-gassed when the Al2O3 films are thinned to 8 nm and annealed above 650°C. Eventually, the entire PERC with the improved triple-layer SiO2/Al2O3/SiNx:H stacked passivation film has an obvious gain in open-circuit voltage (V oc) and short-circuit current (J sc) because of the increased minority carrier lifetime and internal rear-side reflectance, respectively. The electrical performance of the optimized PERC with the V oc of 0.647 V, J sc of 38.2 mA/cm(2), fill factor of 0.776, and the efficiency of 19.18% can be achieved.

No MeSH data available.


Related in: MedlinePlus