Bulk defect formation under light soaking in seed-end n-type Czochralski silicon wafers – Effect on silicon heterojunction solar cells

Letty, Elénore; Veirman, Jordi; Favre, Wilfried; Lemiti, M.

doi:10.1016/j.solmat.2017.03.019

Cited by 8 publications

(2 citation statements)

References 33 publications

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“…In addition, n‐type Cz wafers can also suffer from LID, as reported by Letty et al for seed‐end wafers. [ 51 ] N‐type Cz wafers are also susceptible to reductions in lifetime due to thermal donors. [ 52 ] Thermal donors are recombination‐active defects thought to be formed via the aggregation of silicon and interstitial oxygen atoms.…”

Section: Defect Engineering Approachesmentioning

confidence: 99%

Progress with Defect Engineering in Silicon Heterojunction Solar Cells

Wright

Stefani

Soeriyadi

et al. 2021

Physica Rapid Research Ltrs

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Silicon heterojunction (SHJ) solar cells are formed by the deposition of stacks of intrinsic and doped hydrogenated amorphous silicon layers (a-Si:H) on the surface of crystalline silicon (c-Si) wafers. [1][2][3] The doped a-Si:H layers determine the carrier selectivity of each contact, which defines the direction of current flow, and the intrinsic a-Si:H layers, which are deposited directly onto the crystalline silicon (c-Si) surface, provide excellent surface passivation. [4,5] The cells are completed by the deposition of a transparent conducting oxide (TCO) to aid lateral conduction and the formation of metal contacts, typically by screen printing of silver. [6][7][8] This technology was pioneered in the 1990s by Japanese company Sanyo. [9][10][11] The solar photovoltaics (PV) market is currently dominated by the passivated emitter and rear cell (PERC) design. [12,13] Compared to PERC, SHJ solar cells have multiple advantages. They have demonstrated higher open circuit voltages (V OC ), with V OC values as high as 750 mV. [9] The high V OC is related to the excellent surface passivation provided by the a-Si:H layers. The world record 1 sun efficiency of 26.7% for a single-junction silicon solar cell was achieved using this approach, [14] and cells with efficiency exceeding 25% have been fabricated in an industrial environment. [15] Another advantage of SHJ cells, which is linked to the high V OC , is the lower temperature coefficient, meaning that power losses in SHJ cells operated at elevated temperatures are lower than in other siliconbased technologies. [2,16] Therefore, under realistic cell-operation conditions in the field, the actual power output of an SHJ module will be higher than that of a PERC module, even if they have the same power rating at room temperature. In addition, the expected rise of tandem solar cells with silicon as the bottom cell has also increased interest in the SHJ technology, as it is well suited as the bottom cell in a tandem device. [17][18][19][20][21][22] These advantages mean that industry is seriously looking into SHJ solar cells as a technology to compete with PERC in the future. The ITRPV 11th edition indicates that the market share for SHJ cells is expected to increase to 15% over the next ten years [23] which will represent a significant volume as we move toward terawatt-scale photovoltaics. [24] One unique aspect of SHJ cells is that all processing occurs in a low-temperature regime, typically <250 C. [4,16,25] This is very different to most other cell architectures, such as aluminium

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Section: Defect Engineering Approachesmentioning

confidence: 99%

Progress with Defect Engineering in Silicon Heterojunction Solar Cells

Wright

Stefani

Soeriyadi

et al. 2021

Physica Rapid Research Ltrs

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“…Phosphorus also has a smaller segregation coefficient (0.35) [55,56] than that of boron, leading to larger variations in the bulk doping throughout the ingot. More recently, other LID effects have also been observed in the seed-end of n-type Cz ingots that can reduce performance by 10% relative [64].…”

Section: Decreasing the Boron Doping Concentrationmentioning

confidence: 99%

Eliminating Light-Induced Degradation in Commercial p-Type Czochralski Silicon Solar Cells

et al. 2017

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This paper discusses developments in the mitigation of light-induced degradation caused by boron-oxygen defects in boron-doped Czochralski grown silicon. Particular attention is paid to the fabrication of industrial silicon solar cells with treatments for sensitive materials using illuminated annealing. It highlights the importance and desirability of using hydrogen-containing dielectric layers and a subsequent firing process to inject hydrogen throughout the bulk of the silicon solar cell and subsequent illuminated annealing processes for the formation of the boron-oxygen defects and simultaneously manipulate the charge states of hydrogen to enable defect passivation. For the photovoltaic industry with a current capacity of approximately 100 GW peak, the mitigation of boron-oxygen related light-induced degradation is a necessity to use cost-effective B-doped silicon while benefitting from the high-efficiency potential of new solar cell concepts.

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