Doping Profile Recognition Applied to Silicon Photovoltaic Cells Using Terahertz Time-Domain Spectroscopy

Here we demonstrate for the first time that terahertz time-domain spectroscopy (THz-TDS) can be used to monitor doping profiles in standard industry silicon wafers and commercial multi-crystalline silicon (mc-Si) solar cells. The proof-of-concept results presented here demonstrate the suitability of the technique for in-line, or close to real-time, process and quality control applications in the photovoltaic (PV) industry. The experimental results show that THz pulses can detect changes in implant dosage in both the time and frequency domains. It is also shown that the spectral content of THz pulses can be used to distinguish between doping profiles with identical implant dosages but different profile shapes (resulting from different diffusion times). The reliability and repeatability of these measurements is demonstrated. It is found that the average change in THz spectrum (12.3%) corresponding to the smallest doping profile difference detected is an order of magnitude bigger than the average day-to-day measurement error (1.1%). The THz measurement approach is shown to be fully compatible with the surface morphology (texturing) of commercial mc-Si solar cells.

[1]  D. Grischkowsky,et al.  Terahertz time-domain spectroscopy characterization of the far-infrared absorption and index of refraction of high-resistivity, float-zone silicon , 2004 .

[2]  Ryoichi Fukasawa,et al.  Terahertz imaging of silicon wafers , 2002 .

[3]  Yun-Shik Lee,et al.  Principles of Terahertz Science and Technology , 2008 .

[4]  X. Zhang,et al.  Pulsed terahertz tomography , 2004 .

[5]  P. Siegel.  Terahertz Pioneer: David H. Auston , 2011, IEEE Transactions on Terahertz Science and Technology.

[6]  M Unlu,et al.  Significant performance enhancement in photoconductive terahertz optoelectronics by incorporating plasmonic contact electrodes. , 2013, Nature communications.

[7]  Daniel R. Grischkowsky,et al.  Characterization of an optoelectronic terahertz beam system , 1990 .

[8]  D B Tanner,et al.  Exploring the dynamics of superconductors by time-resolved far-infrared spectroscopy. , 2000, Physical review letters.

[9]  C. Ong,et al.  Optical absorption measurements of band-gap shrinkage in moderately and heavily doped silicon , 1991 .

[10]  Charles A Schmuttenmaer,et al.  Exploring dynamics in the far-infrared with terahertz spectroscopy. , 2004, Chemical reviews.

[11]  Victor S Batista,et al.  Synergistic effect between anatase and rutile TiO2 nanoparticles in dye-sensitized solar cells. , 2009, Dalton transactions.

[12]  K. Kawase,et al.  Non-destructive terahertz imaging of illicit drugs using spectral fingerprints. , 2003, Optics express.

[13]  M Pepper,et al.  Analysis of sustained-release tablet film coats using terahertz pulsed imaging. , 2007, Journal of controlled release : official journal of the Controlled Release Society.

[14]  Masanori Hangyo,et al.  Measurement of optical properties of highly doped silicon by terahertz time domain reflection spectroscopy , 2001 .

[15]  R Alan Cheville.  Terahertz Time-Domain Spectroscopy with Photoconductive Antennas , 2007 .

[16]  Xiaofei Lu,et al.  Balanced terahertz wave air-biased-coherent-detection , 2011 .

[17]  Xi-Cheng Zhang,et al.  T-Ray Sensing and Imaging , 2003 .

[18]  D. Chemla,et al.  Ultrafast terahertz probes of transient conducting and insulating phases in an electron–hole gas , 2003, Nature.

[19]  Gintaras Valušis,et al.  Solar cell imaging and characterization by terahertz techniques , 2012, Optical Engineering + Applications.

[20]  Charles A Schmuttenmaer,et al.  Ultrafast carrier dynamics in nanostructures for solar fuels. , 2014, Annual review of physical chemistry.

[21]  Duncan Graham-Rowe,et al.  Terahertz takes to the stage , 2007 .

[22]  R. F. Wood,et al.  Optical Properties of Heavily Doped Silicon between 1.5 and 4.1 eV , 1981 .

[23]  Zhang Xi,et al.  Materials for terahertz science and technology , 2003 .

[24]  Charles A Schmuttenmaer,et al.  Exciton-like trap states limit electron mobility in TiO2 nanotubes. , 2010, Nature nanotechnology.

[25]  D. Auston.  Picosecond optoelectronic switching and gating in silicon , 1975 .

[26]  Xiang Zhang,et al.  Introduction to THz Wave Photonics , 2009 .

[27]  S. Lupi.  Terahertz Spectroscopy of Novel Superconductors , 2011 .

[28]  K. Humphreys,et al.  Medical applications of terahertz imaging: a review of current technology and potential applications in biomedical engineering , 2004, The 26th Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[29]  Xicheng Zhang,et al.  Terahertz Wave Air Photonics: Terahertz Wave Generation and Detection With Laser-Induced Gas Plasma , 2011, IEEE Journal of Selected Topics in Quantum Electronics.

[30]  A. Bentzen,et al.  Correspondence between sheet resistance and emitter profile of phosphorus diffused emitters from a spray-on dopant , 2005, Conference Record of the Thirty-first IEEE Photovoltaic Specialists Conference, 2005..

[31]  D. Mittleman,et al.  T-ray tomography , 1997, CLEO '97., Summaries of Papers Presented at the Conference on Lasers and Electro-Optics.

[32]  Robert C. Snoeberger,et al.  Hydroxamate anchors for water-stable attachment to TiO2 nanoparticles , 2009 .

[33]  Farhan Rana,et al.  Ultrafast optical-pump terahertz-probe spectroscopy of the carrier relaxation and recombination dynamics in epitaxial graphene. , 2008, Nano letters.

[34]  Wai Lam Chan,et al.  Imaging with terahertz radiation , 2007 .

[35]  Yaochun Shen,et al.  Analysis of coating structures and interfaces in solid oral dosage forms by three dimensional terahertz pulsed imaging. , 2007, Journal of pharmaceutical sciences.

[36]  Daniel R. Grischkowsky,et al.  Nature of Conduction in Doped Silicon , 1997 .

[37]  R. Leitner,et al.  Investigation of charge carrier dynamics in silicon wafers using terahertz imaging spectroscopy , 2012, 2012 IEEE International Instrumentation and Measurement Technology Conference Proceedings.

[38]  Thomas Rades,et al.  Terahertz pulsed imaging as an advanced characterisation tool for film coatings--a review. , 2013, International journal of pharmaceutics.

[39]  X C Zhang,et al.  Terahertz wave imaging: horizons and hurdles. , 2002, Physics in medicine and biology.

[40]  J. L. Tomaino,et al.  Terahertz imaging of inhomogeneous electrodynamics in single-layer graphene embedded in dielectrics , 2012 .

[41]  M. Beard,et al.  Progress towards two-dimensional biomedical imaging with THz spectroscopy. , 2002, Physics in medicine and biology.

[42]  B. Ferguson,et al.  T-ray computed tomography. , 2002, Optics letters.

[43]  R. Newman,et al.  Defects in silicon , 1982 .

[44]  Daniel R. Grischkowsky,et al.  Optical and electronic properties of doped silicon from 0.1 to 2 THz , 1990 .

[45]  Chih-Yu Jen,et al.  Silicon wafer thickness measurement using terahertz time domain spectroscopy main , 2014, Photonics West - Optoelectronic Materials and Devices.