Mapping boron in silicon solar cells using electron energy-loss spectroscopy

Martial Duchamp; András Kovács; Shima Kadkhodazadeh; Chris Boothroyd; Ramona Valentina Mateiu; Bas B. Van Aken; Simon B. Newcomb; Rafal E. Dunin-Borkowski

Mapping boron in silicon solar cells using electron energy-loss spectroscopy

Martial Duchamp (Author), András Kovács (Author), Shima Kadkhodazadeh (Author), Chris Boothroyd (Author), Ramona Valentina Mateiu (Author), Bas B. Van Aken (Author), Simon B. Newcomb (Author), Rafal E. Dunin-Borkowski (Author)

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Abstract

Amorphous silicon solar cells typically consist of stacked layers deposited on plastic or metallic substrates making sample preparation for transmission electron microscopy (TEM) difficult. The amorphous silicon layer - the active part of the solar cell - is sandwiched between 10-nm-thick n- and p-doped layers. The typical boron concentration in the p-doped layer is ~10^21cm -3 and should not exceed 1017cm-3 in the neighbouring intrinsic (i) layer [1], where it acts as a charge recombination centre and decreases the internal electric field [2]. The detection of low boron concentrations with high spatial resolution using TEM is highly challenging [3]. Recently, scanning TEM (STEM) combined with electron energy-loss spectroscopy (EELS) and spherical aberration-correction has allowed the direct detection of dopant concentration of 10^20cm-3 in 65-nm-wide silicon devices [4]. Here, we prepare TEM samples by focused ion beam milling in order to map the boron distribution across a 200-nm-thick n-p amorphous silicon junction using energy-filtered TEM and EELS spectrum acquisition. EELS line scans are used to detect boron concentrations as low as 10^20cm-3. We also use monochromated EELS to measure changes in the energies of plasmon peaks in the low loss region [5]. We use these approaches to characterize both a thick n-p junction and the 10-nm-thick p-doped layer of a working solar cell. [1] U. Kroll, C. Bucher, S. Benagli, I. Schönbächler, J. Meier, A. Shah, J. Ballutaud, A. Howling, Ch. Hollenstein, A. Büchel, M. Poppeller, Thin Solid Films 451 (2004) 525 [2] B. Rech, H. Wagner, Applied Physics A 69 (1999) 155 [3] C.B. Boothroyd, K. Sato, K. Yamada, Proceedings of the XIIth international congress for electron microscopy, ed LD Peachey and DB Williams (San Francisco Press, San Francisco, 1990) 80 [4] K. Asayama, N. Hashikawa, K. Kajiwara, T. Yaguchi, M. Konno, H. Mori, Applied Physics Express 1 (2008) 074001 [5] V. Olevano, L. Reining, Physical Review Letters 86 (2001) 5962

Original language	English
Publication date	2010
Publication status	Published - 2010
Event	7th Workshop on EELS/EFTEM - Zürich, Switzerland Duration: 27 Oct 2010 → 29 Oct 2010 Conference number: 7

Workshop

Workshop	7th Workshop on EELS/EFTEM
Number	7
Country/Territory	Switzerland
City	Zürich
Period	27/10/2010 → 29/10/2010

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title = "Mapping boron in silicon solar cells using electron energy-loss spectroscopy",

abstract = "Amorphous silicon solar cells typically consist of stacked layers deposited on plastic or metallic substrates making sample preparation for transmission electron microscopy (TEM) difficult. The amorphous silicon layer - the active part of the solar cell - is sandwiched between 10-nm-thick n- and p-doped layers. The typical boron concentration in the p-doped layer is ~10^21cm -3 and should not exceed 1017cm-3 in the neighbouring intrinsic (i) layer [1], where it acts as a charge recombination centre and decreases the internal electric field [2]. The detection of low boron concentrations with high spatial resolution using TEM is highly challenging [3]. Recently, scanning TEM (STEM) combined with electron energy-loss spectroscopy (EELS) and spherical aberration-correction has allowed the direct detection of dopant concentration of 10^20cm-3 in 65-nm-wide silicon devices [4]. Here, we prepare TEM samples by focused ion beam milling in order to map the boron distribution across a 200-nm-thick n-p amorphous silicon junction using energy-filtered TEM and EELS spectrum acquisition. EELS line scans are used to detect boron concentrations as low as 10^20cm-3. We also use monochromated EELS to measure changes in the energies of plasmon peaks in the low loss region [5]. We use these approaches to characterize both a thick n-p junction and the 10-nm-thick p-doped layer of a working solar cell. [1] U. Kroll, C. Bucher, S. Benagli, I. Sch{\"o}nb{\"a}chler, J. Meier, A. Shah, J. Ballutaud, A. Howling, Ch. Hollenstein, A. B{\"u}chel, M. Poppeller, Thin Solid Films 451 (2004) 525 [2] B. Rech, H. Wagner, Applied Physics A 69 (1999) 155 [3] C.B. Boothroyd, K. Sato, K. Yamada, Proceedings of the XIIth international congress for electron microscopy, ed LD Peachey and DB Williams (San Francisco Press, San Francisco, 1990) 80 [4] K. Asayama, N. Hashikawa, K. Kajiwara, T. Yaguchi, M. Konno, H. Mori, Applied Physics Express 1 (2008) 074001 [5] V. Olevano, L. Reining, Physical Review Letters 86 (2001) 5962",

author = "Martial Duchamp and Andr{\'a}s Kov{\'a}cs and Shima Kadkhodazadeh and Chris Boothroyd and Mateiu, {Ramona Valentina} and {Van Aken}, {Bas B.} and Newcomb, {Simon B.} and Dunin-Borkowski, {Rafal E.}",

year = "2010",

language = "English",

note = "7th Workshop on EELS/EFTEM ; Conference date: 27-10-2010 Through 29-10-2010",

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A2 - Duchamp, Martial

A2 - Kovács, András

A2 - Kadkhodazadeh, Shima

A2 - Boothroyd, Chris

A2 - Mateiu, Ramona Valentina

A2 - Van Aken, Bas B.

A2 - Newcomb, Simon B.

A2 - Dunin-Borkowski, Rafal E.

N1 - Conference code: 7

PY - 2010

Y1 - 2010

N2 - Amorphous silicon solar cells typically consist of stacked layers deposited on plastic or metallic substrates making sample preparation for transmission electron microscopy (TEM) difficult. The amorphous silicon layer - the active part of the solar cell - is sandwiched between 10-nm-thick n- and p-doped layers. The typical boron concentration in the p-doped layer is ~10^21cm -3 and should not exceed 1017cm-3 in the neighbouring intrinsic (i) layer [1], where it acts as a charge recombination centre and decreases the internal electric field [2]. The detection of low boron concentrations with high spatial resolution using TEM is highly challenging [3]. Recently, scanning TEM (STEM) combined with electron energy-loss spectroscopy (EELS) and spherical aberration-correction has allowed the direct detection of dopant concentration of 10^20cm-3 in 65-nm-wide silicon devices [4]. Here, we prepare TEM samples by focused ion beam milling in order to map the boron distribution across a 200-nm-thick n-p amorphous silicon junction using energy-filtered TEM and EELS spectrum acquisition. EELS line scans are used to detect boron concentrations as low as 10^20cm-3. We also use monochromated EELS to measure changes in the energies of plasmon peaks in the low loss region [5]. We use these approaches to characterize both a thick n-p junction and the 10-nm-thick p-doped layer of a working solar cell. [1] U. Kroll, C. Bucher, S. Benagli, I. Schönbächler, J. Meier, A. Shah, J. Ballutaud, A. Howling, Ch. Hollenstein, A. Büchel, M. Poppeller, Thin Solid Films 451 (2004) 525 [2] B. Rech, H. Wagner, Applied Physics A 69 (1999) 155 [3] C.B. Boothroyd, K. Sato, K. Yamada, Proceedings of the XIIth international congress for electron microscopy, ed LD Peachey and DB Williams (San Francisco Press, San Francisco, 1990) 80 [4] K. Asayama, N. Hashikawa, K. Kajiwara, T. Yaguchi, M. Konno, H. Mori, Applied Physics Express 1 (2008) 074001 [5] V. Olevano, L. Reining, Physical Review Letters 86 (2001) 5962

AB - Amorphous silicon solar cells typically consist of stacked layers deposited on plastic or metallic substrates making sample preparation for transmission electron microscopy (TEM) difficult. The amorphous silicon layer - the active part of the solar cell - is sandwiched between 10-nm-thick n- and p-doped layers. The typical boron concentration in the p-doped layer is ~10^21cm -3 and should not exceed 1017cm-3 in the neighbouring intrinsic (i) layer [1], where it acts as a charge recombination centre and decreases the internal electric field [2]. The detection of low boron concentrations with high spatial resolution using TEM is highly challenging [3]. Recently, scanning TEM (STEM) combined with electron energy-loss spectroscopy (EELS) and spherical aberration-correction has allowed the direct detection of dopant concentration of 10^20cm-3 in 65-nm-wide silicon devices [4]. Here, we prepare TEM samples by focused ion beam milling in order to map the boron distribution across a 200-nm-thick n-p amorphous silicon junction using energy-filtered TEM and EELS spectrum acquisition. EELS line scans are used to detect boron concentrations as low as 10^20cm-3. We also use monochromated EELS to measure changes in the energies of plasmon peaks in the low loss region [5]. We use these approaches to characterize both a thick n-p junction and the 10-nm-thick p-doped layer of a working solar cell. [1] U. Kroll, C. Bucher, S. Benagli, I. Schönbächler, J. Meier, A. Shah, J. Ballutaud, A. Howling, Ch. Hollenstein, A. Büchel, M. Poppeller, Thin Solid Films 451 (2004) 525 [2] B. Rech, H. Wagner, Applied Physics A 69 (1999) 155 [3] C.B. Boothroyd, K. Sato, K. Yamada, Proceedings of the XIIth international congress for electron microscopy, ed LD Peachey and DB Williams (San Francisco Press, San Francisco, 1990) 80 [4] K. Asayama, N. Hashikawa, K. Kajiwara, T. Yaguchi, M. Konno, H. Mori, Applied Physics Express 1 (2008) 074001 [5] V. Olevano, L. Reining, Physical Review Letters 86 (2001) 5962

M3 - Sound/Visual production (digital)

T2 - 7th Workshop on EELS/EFTEM

Y2 - 27 October 2010 through 29 October 2010

ER -

Mapping boron in silicon solar cells using electron energy-loss spectroscopy

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Workshop

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