SEMI PV13 - Test Method for Contactless Excess-Charge-Carrier Recombination Lifetime Measurement in Silicon Wafers, Ingots, and Bricks Using an Eddy-Current Sensor

Volume(s): Photovoltaic
Language: English
Type: Single Standards Download (.pdf)
Abstract

This Standard was technically approved by the Photovoltaic – Materials Global Technical Committee. This edition was approved for publication by the global Audits and Reviews Subcommittee on May 12, 2014. Available at www.semiviews.org and www.semi.org in July 2014; originally published November 2011; previously published August 2013.

 

The excess-charge-carrier (hereafter referred to as ‘excess-carrier’) recombination lifetime is the central parameter to silicon solar cell device design, production, and process control. The measurement of this lifetime as it depends on excess-carrier density yields physically significant results, which allows for design optimization and efficiency prediction in solar cells. The Test Method also describes how this recombination lifetime can be further analyzed in terms of more fundamental parameters of importance to solar cells, such as the bulk lifetime, surface recombination velocity, or the emitter saturation current density of the dopant diffusion. This Test Method includes measurement by quasi-steady-state photoconductance (QSSPC) and transient techniques using an eddy-current sensor.

 

This Standard describes methods for measuring the excess-carrier lifetime in silicon wafers, ingots, and bricks with carrier recombination lifetime in the range of 0.1 to 15,000 µs.

 

The measurements are applicable in the excess-carrier density range from 1 × 1013 cm-3 to 2 × 1016 cm-3 for wafer specimens, and 1 × 1013 cm-3 to 5 × 1015 cm-3 for bulk specimens (thicker than 1 cm).

 

The method described here is used for specimens with resistivity in the range from 0.1 Ω∙cm to 10000 Ω∙cm.

 

This Standard describes four measurement methodologies; two each for the assessment of wafered or bulk silicon specimens. All measurement techniques are performed using an inductive-coil (eddy-current) sensor energized at a radio frequency and an illumination source. Two of the methods use a QSSPC technique that requires a light-intensity detector to measure the photogeneration. The scope of this document also addresses the calibration method to be used.

 

Transient Mode for Wafers — This Test Method is appropriate for a silicon specimen in wafer form, of a thickness not to exceed 1 mm. As described in this Standard, the transient mode is used for excess-carrier lifetimes which are long compared to the cut-off time of the illumination.

 

QSSPC Mode for Wafers — This Test Method is appropriate for wafer specimens of a thickness not to exceed 1 mm. As described in this Standard, the QSSPC Mode is used to determine lifetime by analyzing data taken during photo excitation.

 

Transient Mode for Bulk Material — This Test Method shall be used to measure specimens with a thickness greater than 1 cm, and is used to measure carrier lifetimes that are much longer than the cut-off time of the illumination.

 

QSSPC Mode for Bulk Material — This Test Method shall be used for specimens greater than 1 cm, and determines carrier recombination lifetime by analyzing data taken during photoexcitation.

 

Referenced SEMI Standards

SEMI M59 — Terminology for Silicon Technology


SEMI MF28 — Test Methods for Minority Carrier Lifetime in Bulk Germanium and Silicon by Measurement of Photoconductivity Decay


SEMI MF43 — Test Methods for Resistivity of Semiconductor Materials


SEMI MF84 — Test Method for Measuring Resistivity of Silicon Wafers With an In-Line Four-Point Probe


SEMI MF533 — Test Methods for Thickness and Thickness Variation of Silicon Wafers


SEMI MF723 — Practice for Conversion Between Resistivity and Dopant Density for Boron-Doped, Phosphorus-Doped and Arsenic-Doped Silicon



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