Blistering in ALD Al2O3 passivation layers as rear contacting for local Al BSF Si solar cells

Vermang, Bart; Goverde, Hans; Urueña, A.; Lorenz, Anne; Cornagliotti, Emanuele; Rothschild, A.; John, Joachim; Poortmans, Jef; Mertens, R.

doi:10.1016/j.solmat.2012.01.032

Cited by 46 publications

(38 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…One of the main reasons to avoid blistering is the expectation that it reduces the surface passivation and thereby the efficiency of the solar cell, as reported in [5]. To study the relationship between the minority carrier lifetime and blistering, samples were deposited with 24 nm Al 2 O 3 using two deposition temperatures (T dep ).…”

Section: E Blisters In Relation To Minority Carrier Lifetimementioning

confidence: 99%

“…A post-deposition anneal causes hydrogen, present in OH-bonds, to diffuse to the Al 2 O 3 /Si interface to passivate dangling bonds [3,4]. However, local de-lamination of the Al 2 O 3 layer, also known as blisters, can occur during these temperature treatments [5,6,7]. The formation of blisters starts under the same conditions as gaseous desorption of hydrogen begins [7].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Analysis of blister formation in spatial ALD Al<inf>2</inf>O<inf>3</inf> for silicon surface passivation

Hennen

Granneman²,

Kessels

2012

2012 38th IEEE Photovoltaic Specialists Conference

View full text Add to dashboard Cite

Aluminum oxide (Al 2 O 3 ) thin films yield excellent surface passivation of silicon solar cells. However, unwanted delamination, known as blisters, can occur upon annealing. In this research, blistering is linked to hydrogen diffusion in the bulk. Results reveal competition between diffusion lateral and perpendicular to the interface. Therefore, large blister densities coincide with small blister diameters and vice versa. The total blister volume, however, is independent of blister size distribution, but linked to hydrogen diffusion from the Al 2 O 3 bulk. The blister volume was determined using AFM measurements, which show identical blister shapes for different blister sizes. Additionally, no direct relationship between blister formation and minority carrier was found.

show abstract

Section: E Blisters In Relation To Minority Carrier Lifetimementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Analysis of blister formation in spatial ALD Al<inf>2</inf>O<inf>3</inf> for silicon surface passivation

Hennen

Granneman²,

Kessels

2012

2012 38th IEEE Photovoltaic Specialists Conference

View full text Add to dashboard Cite

show abstract

“…Capacitance-voltage measurements are used to separate changes in charge-assisted and chemical surface passivation. [17][18][19][20]. However, no conclusive correlation between visible blistering and changes in surface passivation has been reported.…”

Section: Introductionmentioning

confidence: 99%

Thermal stability of silicon surface passivation by APCVD Al2O3

Black

Allen

Cuevas

et al. 2014

Solar Energy Materials and Solar Cells

View full text Add to dashboard Cite

a b s t r a c tWe investigate the thermal stability of silicon surface passivation provided by aluminium oxide (Al 2 O 3 ) films deposited using atmospheric pressure chemical vapour deposition (APCVD) and fired in a belt furnace at a peak temperature of $ 810 1C. Firing stability is investigated for p-and n-type substrates as a function of Al 2 O 3 film thickness both with and without a plasma-enhanced chemical vapour deposition (PECVD) SiN x capping layer, and for boron-diffused surfaces with a $ 10 nm Al 2 O 3 film only. Excellent thermal stability of the passivation is demonstrated, with effective carrier lifetimes in n-type silicon wafers remaining stable or even improving after firing, and lifetimes in p-type wafers initially degrading slightly but recovering to above their initial values following $ 10 min illumination by a halogen lamp at $ 20 mW/cm 2 . Film thickness appears to be unimportant to stability, as does the presence of the capping layer. Surface recombination velocities of less than 3 cm/s for 1.35 Ω cm p-type and less than 2 cm/s for 1.2 Ω cm n-type substrates are measured after firing and illumination. The passivation of boron-diffused surfaces is also shown to improve slightly following firing, with a post-firing saturation current density of 42 fA/cm 2 on a diffusion with a sheet resistance of 100 Ω/□ and surface dopant concentration of $ 1.3 Â 10 19 cm −3 . Capacitance-voltage (C-V) measurements show that short firing times result in an initial reduction of the interface defect density D it and a slight increase of the negative insulator fixed charge density Q f , while longer firing results in a substantial increase in both Q f and D it .

show abstract

“…It has been reported that the size and density of the blisters is directly related to the AlO x thickness after a subsequent firing treatment [2]. Blistering can be avoided if the deposited film is thin enough (< 10 nm) and by performing an annealing step at 600 °C before the deposition of a capping layer (outgassing) [3] - [4]. Also, increasing the deposition temperature (> 250 °C) in a plasma-enhanced ALD process helps to avoid blistering [5].…”

Section: Introductionmentioning

confidence: 99%

Effect of ALD reactants on blistering of aluminum oxide films on crystalline silicon

Repo

Gastrow

et al. 2013

2013 IEEE 39th Photovoltaic Specialists Conference (PVSC)

View full text Add to dashboard Cite

Atomic layer deposited aluminum oxide (Al 2 O 3 ) has in recent years proven to be a promising surface passivation material for crystalline silicon solar cells. However, blistering in Al 2 O 3 films is a common problem deteriorating the surface passivation quality. Here, blistering is studied from material aspects including film thickness, film composition and postdeposition heat treatment. We show how thicker films, higher annealing temperatures and longer annealing times lead to more severe blistering and demonstrate how blistering can be avoided by using either O 3 as the oxidant or depositing a thin TiO 2 layer at the silicon interface.

show abstract

Blistering in ALD Al2O3 passivation layers as rear contacting for local Al BSF Si solar cells

Cited by 46 publications

References 11 publications

Analysis of blister formation in spatial ALD Al<inf>2</inf>O<inf>3</inf> for silicon surface passivation

Analysis of blister formation in spatial ALD Al<inf>2</inf>O<inf>3</inf> for silicon surface passivation

Thermal stability of silicon surface passivation by APCVD Al2O3

Effect of ALD reactants on blistering of aluminum oxide films on crystalline silicon

Contact Info

Product

Resources

About