Simulation Results: Optimization of Contact Ratio for Interdigitated Back-Contact Solar Cells

Budhraja, Vinay; Devayajanam, Srinivas; Basnyat, Prakash

doi:10.1155/2017/7818914

Cited by 3 publications

(1 citation statement)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While previous studies using simulations have investigated the optimal dimensions, electrical properties, and passivation quality of the doped fingers, − a majority of these studies regard the region between the intentionally doped fingers as insulating. However, in experimentally fabricated devices, dopants are known to spread into the nominally intrinsic poly-Si isolation region between the n- and p-doped fingers through multiple mechanisms: diffusion during high-temperature annealing steps, incomplete masking, and gas-phase transfer .…”

Section: Introductionmentioning

confidence: 96%

Trap-Assisted Dopant Compensation Prevents Shunting in Poly-Si Passivating Interdigitated Back Contact Silicon Solar Cells

Hartenstein

Stetson

Nemeth

et al. 2021

ACS Appl. Energy Mater.

View full text Add to dashboard Cite

Using a trap-assisted compensation model, we explain why polycrystalline Si (poly-Si) passivating contacts are able to achieve low leakage current between the doped fingers of interdigitated back contact (IBC) monocrystalline Si solar cells despite mixing of boron and phosphorus dopants in the isolation region. The fill factor of IBC solar cells is strongly affected by the electrical isolation region between n- and p-type fingers, as this region is critical in minimizing shunting losses. During fabrication of monocrystalline Si solar cells with poly-Si passivating contacts, the intrinsic poly-Si isolation region inevitably gets contaminated with both p- and n-type dopants. Using dopant profiles measured with time-of-flight secondary ion mass spectrometry and scanning probe measurements of the isolation region, we demonstrate that despite the dopant spreading during cell processing, a well-compensated region between the doped fingers exists that prevents shunting. The trap-assisted dopant compensation mechanism significantly widens the compensated region to tens of microns, where the residual dopant densities are below the trap density. This enables a high-resistivity region, resulting in low shunt current. Using one-dimensional (1-D) finite element diode simulations, we identify the design parameters and experimental conditions under which a sufficiently resistive region can form. Our measurements of 2-D local resistivity and work function maps across the isolation region using scanning spreading resistance microscopy and Kelvin probe force microscopy demonstrate the existence of a highly resistive, wide compensated region and confirm our proposed compensation mechanism. For our structures, this region is ∼25 μm in width within a ∼150 μm wide finger isolation region with nearly 3 orders of magnitude higher resistivity than the regions dominated by a single type of dopant.

show abstract