Lifetime mapping of Si wafers by an infrared camera [for solar cell production]

Bail, M.; Kentsch, Jörg; Brendel, Rolf; Schulz, M.

doi:10.1109/pvsc.2000.915763

Cited by 31 publications

(38 citation statements)

References 9 publications

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“…The Infrared Lifetime Mapping (ILM) method was presented the first time in 2000 by Bail et al [2]. Subsequently in 2001 Riepe and coworkers [3] presented a variation on the theme called Carrier Density Imaging (CDI), improved with the lock-in detection technique [77].…”

Section: Infrared Camera Lifetime Mapping/carrier Density Imagingmentioning

confidence: 99%

“…The correction factor takes in account the fact that only wafers with one type of dopant are used in the calibration [2], while the absorbed pump photons generate excess electrons and holes that bring about a variation in the absorbed black body radiation. This correction factor in the case of p-type calibration wafers must be…”

Section: Ilm/cdi Calibrationmentioning

confidence: 99%

“…where and are the absorption coefficients of the free electrons and holes, respectively, at the absorbed radiation wavelength (the black body detected radiation) [2,34,[37][38][39]. Obviously the absorption coefficients must be inverted in (50) if the calibration is performed with n-type wafers.…”

Section: Ilm/cdi Calibrationmentioning

confidence: 99%

“…To quantify the ILM/CDI sensitivity a noise equivalent lifetime (NEL) is defined [2,81] as the effective minority carrier lifetime that the sample must have to generate an infrared camera contrast that equals the camera noise. This quantity is related to camera detection limit (or minimum resolvable contrast), that is, the minimum variation of the incident radiation that the camera can distinguish.…”

Section: Ilm/cdi Sensitivitymentioning

confidence: 99%

“…In this paper we present a review of two important contactless techniques used to determine the semiconductor materials lifetime: the Pump and Probe method (PP) [1] and the Infrared Lifetime Mapping method (ILM), otherwise known as Carriers Density Imaging (CDI) [2,3]. These techniques are based on the free carriers absorption that occurs in the semiconductor materials.…”

Section: Introductionmentioning

confidence: 99%

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Optical Measurement Techniques of Recombination Lifetime Based on the Free Carriers Absorption Effect

Laurentis

Irace

2014

Journal of Solid State Physics

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We review successful measurement techniques for the evaluation of the recombination properties in semiconductor materials based on the optically induced free carrier absorption. All the methodologies presented share the common feature of exploiting a laser beam to excite electron-hole pairs within the volume of the sample under investigation, while the probing methods can vary according to the different methodology analyzed. As recombination properties are of paramount importance in determining the properties of semiconductor devices (i.e, bipolar transistor gain, power devices switching features, and solar cells efficiency), their knowledge allows for better understanding of experimental results and robust TCAD simulator calibration. Being contactless and applicable without any particular preparation of the sample under investigation, they have been considered attractive to monitor these parameters inline or just after production of many different semiconductor devices.

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Section: Infrared Camera Lifetime Mapping/carrier Density Imagingmentioning

confidence: 99%

Section: Ilm/cdi Calibrationmentioning

confidence: 99%

Section: Ilm/cdi Calibrationmentioning

confidence: 99%

Section: Ilm/cdi Sensitivitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Optical Measurement Techniques of Recombination Lifetime Based on the Free Carriers Absorption Effect

Laurentis

Irace

2014

Journal of Solid State Physics

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Microsecond carrier lifetime measurements in silicon via quasi‐steady‐state photoluminescence

Giesecke

Warta

2011

Progress in Photovoltaics

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Modulated quasi-steady-state photoluminescence is used in photovoltaics in order to measure the injection-dependent effective minority carrier lifetime of silicon wafers. In spite of the very advantageous properties of this measurement technique, its wide dissemination in photovoltaics has been hampered so far because of a relatively poor sensitivity limit in terms of carrier lifetime. A systematic analysis of the sensitivity-limiting mechanisms led to a substantial upgrade of sensitivity, tackling the range of effective lifetimes of 1s. This paper discusses the requirements to reach this level of sensitivity. Most prominently, the dependence of a silicon photodiode's response time with respect to the wavelength of the detected light is addressed. As an alternative, InGaAs photodiodes are implemented. The sensitivity of this method with respect to carrier lifetime is evaluated

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Advanced alignment technique for precise printing over selective emitter in c‐Si solar cells

Voltan¹,

Galiazzo²,

Tonini³

et al. 2011

Progress in Photovoltaics

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Significant improvements in c-Si solar cells performance can be achieved acting on the emitter or on the contact formation side. At the moment, an efficiency gain around 0.5-0.6% abs [1] has been demonstrated for selective emitter (SE) cells, mainly caused by the improvement of the blue response of the shallow emitter. Nevertheless, in case of sub-optimal alignment of the printed metal with the deep emitter, the shallow junction depth leads to a significantly narrower firing process window, consequently causing high contact resistance and poor shunting behavior. Moreover, after Anti Reflective Coating (ARC) the contrast between differently doped areas is poor and often prevents the screen printer vision system from correctly recognizing the pattern for metal printing alignment. Thus, we developed a new equipment, high precision selective emitter, for precise alignment over SE able to guarantee recognition of every SE pattern and consequent printing repeatability within +/-30 mm without rejections or misalignments. In this work, results from experimental investigations and mass production are reported and discussed, including also comparison with standard alignment methods and further feasible applications.New equipment for precise alignment over SE able to guarantee recognition of every SE pattern and consequent printing repeatability within +/-30mm without rejections or misalignments has been developed (examples of SE patterns are reported in the following pictures). Test performed at production sites confirm that an efficiency gain of 0.1% and a significant reduction of rejection can result from the increased robustness of the presented method. Finally, also a correlation between sheet resistance of heavily doped area and image contrast has been demonstrated.

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Lifetime mapping of Si wafers by an infrared camera [for solar cell production]

Cited by 31 publications

References 9 publications

Optical Measurement Techniques of Recombination Lifetime Based on the Free Carriers Absorption Effect

Optical Measurement Techniques of Recombination Lifetime Based on the Free Carriers Absorption Effect

Microsecond carrier lifetime measurements in silicon via quasi‐steady‐state photoluminescence

Advanced alignment technique for precise printing over selective emitter in c‐Si solar cells

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