Analytical Theory for Extracting Specific Contact Resistances of Thick Samples From the Transmission Line Method

Eidelloth, S.; Brendel, Rolf

doi:10.1109/led.2013.2290602

Cited by 44 publications

(28 citation statements)

References 14 publications

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“…The sheet resistance of TCO layers is determined by 4‐probe measurement. The TCO/Ag specific contact resistance ( ρ TCO/Ag ) is measured on a TLM structure . R TCO , R metallization , and R TCO/Ag are then calculated based on the unit cell approach .…”

Section: Resultsmentioning

confidence: 99%

Study and development of rear‐emitter Si heterojunction solar cells and application of direct copper metallization

Yang

Zhong

Zhang

et al. 2018

Progress in Photovoltaics

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We have presented a comprehensive study on the development of rear emitter silicon heterojunction (SHJ) solar cells, which shows more freedom for device optimization than the standard front emitter SHJ counterparts. The optimization of the p-type hydrogenated amorphous silicon (a-Si:H(p)) layer is liberated from the parasitic absorption issue, while the n-type hydrogenated amorphous silicon (a-Si:H(n)) layer is optimized considering the tradeoff between the light absorption loss and field-effect passivation. The front transparent conductive oxide (TCO) layer can be designed stressing on its optical properties because the lateral transport of the majority carriers at the front side of the cell is supported by the Si substrate, while the rear TCO layer is free to be tuned for suppressing the TCO/a-Si:H(p) contact resistance. A rear emitter SHJ solar cell (225.47 cm 2 ) fabricated by industry compatible process has been achieved with an efficiency of over 22%. We have further demonstrated the replacement of screen-printed silver metallization with a low cost direct copper metallization in the rear emitter SHJ solar cells. We report an exciting 22.06% cell efficiency which is comparable to that of the screen-printed counterpart.

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Section: Resultsmentioning

confidence: 99%

Study and development of rear‐emitter Si heterojunction solar cells and application of direct copper metallization

Yang

Zhong

Zhang

et al. 2018

Progress in Photovoltaics

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“…The results of the TLM measurements performed on the TLM strips are shown in Figure . Please note that due to the sample structure, the determined ρ C values represent upper limits . The Ag paste used is capable of contacting the laser‐processed and p‐doped areas with 1.0 mΩ cm 2 ≤ ρ C ≤ 2.2 mΩ cm 2 for setting 1 and with 1.4 mΩ cm 2 ≤ ρ C ≤ 7.8 mΩ cm 2 for setting 2.…”

Section: Resultsmentioning

confidence: 99%

“…Please note that due to the sample structure, the determined ρ C values represent upper limits. [29] The Ag paste used is capable of contacting the laser-processed and p-doped areas with 1.0 mΩ cm 2 ρ C 2.2 mΩ cm 2 for setting 1 and with 1.4 mΩ cm 2 ρ C 7.8 mΩ cm 2 for setting 2. For setting 1, P laser has no significant impact on the measured ρ C while for setting 2, ρ C increases with increasing P laser .…”

Section: Resultsmentioning

confidence: 99%

Low‐Ohmic Contacting of Laser‐Doped p‐Type Silicon Surfaces with Pure Ag Screen‐Printed and Fired Contacts

Lohmüller

Werner

Norouzi

et al. 2017

Physica Status Solidi (a)

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The state‐of‐the‐art low‐ohmic electrical contacting of highly boron‐doped silicon surfaces is based on the use of screen‐printed and fired silver‐aluminum (Ag‐Al) contacts. For these contacts, metal crystallites with depths of up to a few microns are observed at the interface. For screen‐printed and fired Ag contacts on phosphorus‐doped surfaces, the observed crystallite depths are much smaller. In this work, low‐ohmic electrical contacting of local laser‐doped p‐type silicon surfaces with commercial pure Ag screen‐printing paste are demonstrated. The doping layer is based on the “pPassDop” approach, which serves as a passivation layer on the rear side of p‐type silicon solar cells. The specific contact resistances are measured down to 1 mΩ cm2 for p‐type doping densities of about 3 × 1019 cm−3 at the silicon surface and finger widths of around 55 μm. Microstructure analysis reveals the formation of numerous small Ag crystallites at the interface with penetration depths of less than 80 nm. A first implementation of the “pPassDop” approach on 6‐inch p‐type Cz‐Si bifacial solar cells using solely Ag contacts on both sides results in a peak front side energy conversion efficiency of 19.1%, measured on a black chuck with contact bars on both sides.

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“…A TLM evaluation method was recently proposed, considering a thick sample. 33 The second dimension of the thickness is accounted for in an analytical solution to derive R C,TLM2D for planar contacts. R C,TLM2D % R C-base is 1.16 X assuming q base ¼ 2 X cm, W ¼ 150 lm, a ¼ 50 lm, and q C ¼ 1 Â 10 À6 mX cm 2 .…”

Section: B Evaluation Of R C By the Tlm Methodsmentioning

confidence: 99%

Evaluation of determination methods of the Si/Al contact resistance of screen-printed passivated emitter and rear solar cells

Müller

Lottspeich

2014

Journal of Applied Physics

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The Si/Al contact resistance of narrow p-type contact areas of crystalline silicon solar cells is a crucial parameter for the further development and improvement of passivated emitter and rear (PERC) solar cells. In this paper, two methods for determining the rear contact resistance are analyzed and improved: the series resistance analysis and the transfer length method (TLM). We use an experimental set of PERC solar cells with varying metallization fraction, and we analyze the experiment using numerical device simulation. In the first method, the resistive losses are extracted from the I-V-curves of the PERC cells, and the rear contact resistance is separated by subtracting the analytically calculated base contribution. The state-of-the-art analytical calculations deviate significantly from our numerical simulations, causing a high level of uncertainty that we do not recommend this method (an upper limit of the rear contact resistance per line contact is determined to be about 2 Ω cm). In the second method, the rear line contacts are separated and measured with the TLM. Still, the series resistance loss in the base has to be quantified considering a thick base and the rear line contact geometry. We separate the base component by numerical device simulations and find that the rear contact resistance per line contact is below 0.5 Ω cm. This implies that rear contact resistance reduces cell efficiency of screen-printed PERC solar cells only by about 0.1%abs for metallization fractions higher than 3.5%, i.e., the rear contact resistance is currently no significant loss mechanism in our PERC solar cells. All of our improved evaluations lead to lower resistance values than previously reported and with a reduced uncertainty. The TLM method is suggested to be favorable.

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Analytical Theory for Extracting Specific Contact Resistances of Thick Samples From the Transmission Line Method

Cited by 44 publications

References 14 publications

Study and development of rear‐emitter Si heterojunction solar cells and application of direct copper metallization

Study and development of rear‐emitter Si heterojunction solar cells and application of direct copper metallization

Low‐Ohmic Contacting of Laser‐Doped p‐Type Silicon Surfaces with Pure Ag Screen‐Printed and Fired Contacts

Evaluation of determination methods of the Si/Al contact resistance of screen-printed passivated emitter and rear solar cells

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