Annealing induced amorphous/crystalline silicon interface passivation by hydrogen atom diffusion

Dai, Xiaoying; Cai, Hongkun; Zhang, Dexian; Chen, Guifeng; Wang, Yong; Liu, Wei; Sun, Yun

doi:10.1007/s10854-015-3806-5

Cited by 5 publications

(4 citation statements)

References 26 publications

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“…We also observed an enhancement in τ eff after annealing regardless of the HPT applied on the a-Si:H sample. Thermal annealing has been used by various groups to increase the τ eff of the i-layer , and a detailed investigation has been presented by us elsewhere . The lifetime results demonstrate that both single and double I-HPT have better performances compared to a-Si:H films without any HPT or with Post-HPT at the given pressure.…”

Section: Resultsmentioning

confidence: 99%

Interface Engineering by Intermediate Hydrogen Plasma Treatment Using Dc-PECVD for Silicon Heterojunction Solar Cells

Soman

Das

Hegedus

2023

ACS Appl. Electron. Mater.

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The high open-circuit voltage (V OC) in silicon heterojunction solar cells is attributed to the superior amorphous–crystalline silicon interface passivation. In this work, we investigated a method called intermediate hydrogen plasma treatment (I-HPT) in which the intrinsic amorphous silicon is exposed to hydrogen plasma in between the deposition using direct current (d.c.) plasma-enhanced chemical vapor deposition. This method can not only enhance the surface passivation but also find industrial application due to its ease of integration in the production line. Fourier transform infrared spectroscopy reveals that I-HPT makes the bulk of the amorphous matrix more disordered. We anticipate that the improvement in passivation comes from the diffusion of hydrogen from the bulk to the interface and shifting of the film closer to the “amorphous-to-microcrystalline” transition regime. Our optimized I-HPT method can obtain an implied V OC of 746 mV without annealing, which corresponds to a low surface recombination velocity of 3.2 cm/s. Therefore, we propose the I-HPT method as an alternative to high-temperature annealing which can reduce a fabrication step and processing time. The I-HPT films characterized by Raman spectroscopy do not show any hydrogen-induced crystallization. We have also demonstrated the proof of concept by applying I-HPT to a silicon heterojunction solar cell which shows ∼15 mV increase in V OC in the device and an absolute increase in efficiency by 0.3% as compared to a cell with no HPT.

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Section: Resultsmentioning

confidence: 99%

Interface Engineering by Intermediate Hydrogen Plasma Treatment Using Dc-PECVD for Silicon Heterojunction Solar Cells

Soman

Das

Hegedus

2023

ACS Appl. Electron. Mater.

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“…The change in the partial pressure of the effused hydrogen gas was measured using a quadrupole mass spectrometer (QMS, in Figure S2a), while the test sample was heated from room temperature to 800 °C at a constant heating rate of 5 °C/min under ultrahigh vacuum (<1.0 × 10 –8 Torr). Using an in-house-built hydrogen exodiffusion system having high sensitivity, we could identify the Si–H bonding configurations of each stack with the same stack in SHJ solar cells without requiring an additional attenuated total reflectance mode , or thicker amorphous layers deposited on high-resistivity polished float-zone (FZ) wafers, as required for FTIR measurements.…”

Section: Methodsmentioning

confidence: 99%

Silicon–Hydrogen Bonding Configuration Modified by Layer Stacking Sequence in Silicon Heterojunction Solar Cells

Jeong

et al. 2022

ACS Appl. Energy Mater.

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Recent improvements in highly efficient crystalline silicon (c-Si) solar cells have relied on surface passivation. Hydrogen plays a crucial role in the surface passivation of silicon heterojunction (SHJ) solar cells because Si–H bonds passivate dangling bonds in amorphous silicon and on the c-Si surface. In this work, we demonstrate that the Si–H bonding configuration is modified by layer stacking sequence for SHJs. The quality of surface passivation strongly correlates with low-temperature hydrogen effusion from the SHJ structure. Our results show that the deposition of doped layers on intrinsic amorphous silicon supplies additional hydrogen to the amorphous/crystalline heterostructure. Moreover, the deposition of a p-layer modifies the microstructure of the intrinsic layer underneath, whereas depositing an n-layer does not induce structural changes. We suggest that the low-temperature hydrogen effusion characteristics can be used as a sensitive indicator for examining the passivation quality of SHJ solar cells.

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“…Through fitting, two types of Si−H x bonds were distinguished: Si−H stretching mode (centered at ∼2000 cm −1 ) and Si−H 2 stretching mode (centered at ∼2100 cm −1 ). 15,16 These two types of silicon−hydrogen bonds indicated two different bonding energies for the hydrogen species within the a-Si:H(i) film. Also, the amount of H released from the two types of Si− H x bonds may differ at the same thermal budget (i.e., product of annealing temperature and time), thus could contribute differently to the passivation effect of the SiGe/Si cell, which has been demonstrated on Si solar cells in many previous studies.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Moreover, characteristic peaks associated with hydrogen species in the a-Si:H(i) films are observed in the range of 1800 to 2200 cm −1 (an expanded view is shown in the inset). Through fitting, two types of Si−H x bonds were distinguished: Si−H stretching mode (centered at ∼2000 cm −1 ) and Si−H 2 stretching mode (centered at ∼2100 cm −1 ) 15,16. These two types of silicon−hydrogen bonds indicated two different bonding energies for the hydrogen species within the a-Si:H(i) film.…”

mentioning

confidence: 99%

Study of the Hydrogen Passivation Effect of Low-Temperature-Deposited Amorphous Silicon Layers on SiGe Solar Cells Grown on a Silicon Substrate

Sun,

Wang,

Luo

et al. 2023

ACS Appl. Energy Mater.

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In this study, we explored the use of low-temperature deposited a-Si:H(i) as a hydrogen source for the hydrogenation of SiGe solar cells on Si substrates. Cells integrated with a-Si:H(i) layers exhibited significant performance improvements after thermal annealing, with a maximum enhancement of 50 mV (20.2%rel), 8%abs (15%rel), and 1%abs (44%rel) in V OC, FF, and efficiency, respectively. These results, along with Raman spectroscopy measurements, confirm that hydrogen was released from a-Si:H(i) during thermal treatment and likely diffused into the SiGe/Si cells, providing defect passivation. External quantum efficiency measurements further revealed that the passivation enhancement occurred mainly on the front surface and nearby, indicating that hydrogen primarily diffused into the near-surface region and passivated defects in that area. The correlation between the changes in the hydrogen content from a-Si:H(i) and variations in V OC after thermal annealing was also examined to further understand the hydrogen passivation effect. Overall, this study demonstrates the successful implementation of hydrogenation using a-Si:H(i) as a hydrogen source with significant improvements in cell performance, providing potential pathways for developing efficient SiGe/Si solar cells.

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Annealing induced amorphous/crystalline silicon interface passivation by hydrogen atom diffusion

Cited by 5 publications

References 26 publications

Interface Engineering by Intermediate Hydrogen Plasma Treatment Using Dc-PECVD for Silicon Heterojunction Solar Cells

Interface Engineering by Intermediate Hydrogen Plasma Treatment Using Dc-PECVD for Silicon Heterojunction Solar Cells

Silicon–Hydrogen Bonding Configuration Modified by Layer Stacking Sequence in Silicon Heterojunction Solar Cells

Study of the Hydrogen Passivation Effect of Low-Temperature-Deposited Amorphous Silicon Layers on SiGe Solar Cells Grown on a Silicon Substrate

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