POCl3 diffusion is currently the de facto standard method for industrial n-type emitter fabrication. In this study, we present the impact of the following processing parameters on emitter formation and electrical performance: deposition gas flow ratio, drive-in temperature and duration, drive-in O2 flow rate, and thermal oxidation temperature. By showing their influence on the emitter doping profile and recombination activity, we provide an overall strategy for improving industrial POCl3 tube diffused emitters.
International Technology Roadmap for Photovoltaic. (ITRPV.net) Results 2015 Version 2. 2015
2
J Lossen , K Lauer, L Mittelstädt, S Dauwe, C Beneking. Making use of silicon wafers with low lifetimes by adequate POCl3 diffusion. In: The 20th European Photovolatic Solar Energy Conference. Barcelona, Spain, 2005
3
P Manshanden, L J Geerligs. Improved phosphorous gettering of multicrystalline silicon. Solar Energy Materials and Solar Cells, 2006, 90(7–8): 998–1012
4
J Härkönen, V P Lempinen, T Juvonen, J Kylmäluoma. Recovery of minority carrier lifetime in low-cost multicrystalline silicon. Solar Energy Materials and Solar Cells, 2002, 73(2): 125–130
5
S Joonwichien, I Takahashi, S Matsushima, N Usami. Enhanced phosphorus gettering of impurities in multicrystalline silicon at low temperature. Energy Procedia, 2014, 55: 203–210 https://doi.org/10.1016/j.egypro.2014.08.119
6
V Vacek, S Žáček, I Horsák. Phosphorus and boron diffusion gettering of iron in monocrystalline silicon. Journal of Applied Physics, 2011,109(109): 093505
7
A Bentzen, A Holt, R Kopecek , G Stokkan, J S Christensen. Gettering of transition metal impurities during phosphorus emitter diffusion in multicrystalline silicon solar cell processing. Journal of Applied Physics, 2006, 99(9): 093509
8
G F Cerofolini. M L Polignano, F Nava, G Ottaviani. On the mechanism responsible for phosphorus inactivation in heavily doped silicon. Thin Solid Films, 1982, 97(4): 363–367
9
S Solmi. A Parisini, R Angelucci, A Armigliato, D Nobili. Dopant and carrier concentration in Si in equilibrium with monoclinic SiP precipitates. Physical Review B, 1996, 53(12): 7836–7841
10
A Dastgheib-Shirazi, M Steyer, G Micard, H Wagner, P P Altermatt. Relationships between diffusion parameters and phosphorus precipitation during the POCl3 diffusion process. Energy Procedia, 2013, 38(0): 254–262
11
P Ostoja, S Guerri, P Negrini, S Solmi. The effects of phosphorus precipitation on the open-circuit voltage in N+/P silicon solar cells. Solar Cells, 1984, 11(1): 1–12
12
J C C Tsai. Shallow phosphorus diffusion profiles in silicon. Proceedings of the IEEE, 1969, 57(9): 1499–1506
13
P J Cousins, J E Cotter. The influence of diffusion-induced dislocations on high efficiency silicon solar cells. IEEE Transactions on Electron Devices, 2006, 53(3): 457–464
14
A Kimmerle, A Wolf, U Belledin, D Biro. Modelling carrier recombination in highly phosphorus-doped industrial emitters. Energy Procedia, 2011, 8: 275–281
15
A Wolf, A Kimmerle, S Werner, S Maier, U Belledin, S Meier, D Biro. Status and perspective of emitter formation by POCl3-diffusion. 2015
16
B Bazer-Bachi, E Fourmond, P Papet, L Bounaas, Nichiporu O k. Higher emitter quality by reducing inactive phosphorus. Solar Energy Materials and Solar Cells, 2012, 105(10): 137–141
17
P P Altermatt, J O Schumacher, A Cuevas, M J Kerr, S W Glunz. Numerical modeling of highly doped Si: P emitters based on Fermi–dirac statistics and self-consistent material parameters. Journal of Applied Physics, 2002, 92(6): 3187–3197
18
E Tannenbaum. Detailed analysis of thin phosphorus-diffused layers in p-type silicon. Solid-State Electronics, 1961, 2(2–3): 123–132
19
B L Morris, L E Katz. Reduction of excess phosphorus and elimination of defects in phosphorus emitter diffusions. Journal of the Electrochemical Society, 1978, 125(5): 762–765
20
D Nobili. Precipitation as the phenomenon responsible for the electrically inactive phosphorus in silicon. Journal of Applied Physics, 1982, 53(3): 1484–1491
21
Y Komatsu, A H G Vlooswijk, A F Stassen, P Venema, C Meyer. Sophistication of doping profile manipulation-emitter performance improvement without additional process step. The 25th European Photovoltaic Solar Energy Conference and Exhibition-5th World Conference on Photovoltaic Energy Conversion. Valenia, Spain, 2010, 6: 10
22
M Z Burrows. A Meisel, G Scardera, Lemm F i. Front metal and diffusion optimization for selective emitter. In: 38th IEEE Photovoltaic Specialists Conference (PVSC). 2012: 002138–002141
23
J Zhao, A Wang, M A Green. Emitter design for high-efficiency silicon solar cells. Part I: Terrestrial cells. Progress in Photovoltaics: Research and Applications, 1993, 1(3): 193–202
24
A Cuevas, M Balbuena. Thick-emitter silicon solar cells. In: Photovoltaic Specialists Conference. 1988, 1: 429–434
25
M J Kerr. Surface, emitter and bulk recombination in silicon and development of silicon nitride passivated solar cells. Dissertation for the Doctoral Degree. Canberra: Australian National University, 2002
26
P P Altermatt, A Schenk, G Heiser. A simulation model for the density of states and for incomplete ionization in crystalline silicon. I. Establishing the model in Si: P. Journal of Applied Physics, 2006, 100(11): 113714
27
A Cuevas, M J Kerr, J Schmidt. Passivation of crystalline silicon using silicon nitride. In: Proceedings of 3rd World Conference on Photovoltaic Energy Conversion, 2003, 1: 913–918
28
A Cuevas, P A Basore, G Giroult-Matlakowski, C Dubois. Surface recombination velocity of highly doped n-type silicon. Journal of Applied Physics, 1996, 80(6): 3370–3375
29
M J Kerr, J Schmidt, A Cuevas, J H Bultman. Surface recombination velocity of phosphorus-diffused silicon solar cell emitters passivated with plasma enhanced chemical vapor deposited silicon nitride and thermal silicon oxide. Journal of Applied Physics, 2001, 89(7): 3821–3826
30
R Bock, P P Altermatt, J Schmidt. Accurate extraction of doping profiles from electrochemical capacitance voltage measurements. In: European Photovoltaic Solar Energy Conference. Valencia, Spain. 2008:1(5)
31
R A Sinton, A Cuevas. A quasi-steady-state open-circuit voltage method for solar cell characterization. In: Proceedings of the 16th European Photovoltaic Solar Energy Conference. 2000, 1152
32
D E Kane, R M Swanson. Measurement of the emitter saturation current by a contactless photoconductivity decay method. In: IEEE Photovoltaic Specialists Conference. 1985, 18: 578–583
33
S Duttagupta, F Ma, B Hoex, T Mueller, A G Aberle. Optimised antireflection coatings using silicon nitride on textured silicon surfaces based on measurements and multidimensional modelling. Energy Procedia, 2012, 15(17): 78–83
34
PVLIGHTHOUSE.
35
M Abbott, G Scardera, K R Mcintosh, A Meisel. Simulation of emitter doping profiles formed by industrial POCl3 processes. In: The 39th Photovoltaic Specialists Conference (PVSC). 2013: 1383–1388
36
M D Abbott. An examination of three common assumptions used to simulate recombination in heavily doped silicon. In: Proceedings of the 28th EU PVSEC. Paris, France. 2013: 1672–1679
37
K R McIntosh, L P Johnson. Recombination at textured silicon surfaces passivated with silicon dioxide. Journal of Applied Physics, 2009, 105(12): 124520
38
H Wagner, A Dastgheib-Shirazi, R Chen, S T Dunham, M Kessler. Improving the predictive power of modeling the emitter diffusion by fully including the phosphsilicate glass (PSG) layer. In: Photovoltaic Specialists Conference (PVSC). 2011: 002957–002962
39
R Chen, H Wagner, A Dastgheib-Shirazi, Kessle M r. Understanding coupled oxide growth and phosphorus diffusion in POCl3 deposition for control of phosphorus emitter diffusion. In: Photovoltaic Specialists Conference (PVSC). 2012: 000213–000216
40
G Micard, A Dastgheib-Shirazi , P P Altermatt, T Solar. Advances in the understanding of phosphorus silicate glass (PSG) formation for accurate process simulation of phosphorus diffusion. In: The 27th European Photovoltaic Solar Energy Conference. Frankfurt, Germany. 2012
41
S M Hu, P Fahey, R W Dutton. On models of phosphorus diffusion in silicon. Journal of Applied Physics, 1983, 54(12): 6912–6922
42
P Rothhardt, R Keding, U Belledin, A Wolf, D Biro. Control of phosphorus doping profiles for co-diffusion processes. In: Proceedings of the 27th European Photovoltaic Solar Energy Conference and Exhibition. 2012
43
A Safiei, H Windgassen, K Wolter, H Kurz. Emitter profile tailoring to contact homogeneous high sheet resistance emitter. Energy Procedia, 2012, 27: 432–437
44
P Rothhardt, C Demberger, A Wolf, D Biro. Co-diffusion from APCVD BSG and POCl3 for industrial n-type solar cells. Energy Procedia, 2013, 38: 305–311
45
H J Lee, M G Kang, S J Choi, G H Kang, J M Myoung. Characteristics of silicon solar cell emitter with a reduced diffused phosphorus inactive layer. Current Applied Physics, 2013, 13(8): 1718–1722
46
M C Duffy, F Barson, J M Fairfield, G H Schwuttke. Effects of high phosphorus concentration on diffusion into silicon. Journal of the Electrochemical Society, 1968, 115(1): 84–88
47
M Steyer, A Dastgheib-Shirazi, G Hahn, B Terheiden. New method for determination of electrically inactive phosphorus in n-type emitters. Energy Procedia, 2015, 77: 316–320
48
E Kooi. Formation and composition of surface layers and solubility limits of phosphorus during diffusion in silicon. Journal of the Electrochemical Society, 1964, 111(12): 1383–1387
49
D Kumar, S Saravanan, P Suratkar. Effect of oxygen ambient during phosphorous diffusion on silicon solar cell. Journal of Renewable and Sustainable Energy, 2012, 4(3): 033105
50
R de Rose, M Zanuccoli, P Magnone, M Frei, E Sangiorgi. Understanding the impact of the doping profiles on selective emitter solar cell by two-dimensional numerical simulation. IEEE Journal of Photovoltaics, 2013, 3(1): 159–167
51
A F Carroll. Screen printed metal contacts to Si solar cells-formation and synergistic improvements. In: The 39th Photovoltaic Specialists Conference (PVSC). 2013: 3435–3440
52
D Biro, S Mack, A Wolf, A Lemke, U Belledin. Thermal oxidation as a key technology for high efficiency screen printed industrial silicon solar cells. In: Proceedings of the 34th IEEE Photovoltaic Specialists Conference. PA, USA, 2009: 1594–1599
53
O Schultz, A Mette, M Hermle, S W Glunz. Thermal oxidation for crystalline silicon solar cells exceeding 19% efficiency applying industrially feasible process technology. Progress in Photovoltaics: Research and Applications, 2008, 16(4): 317–324
54
O Schultz, M Hofmann, S W Glunz, G P Willeke. Silicon oxide/silicon nitride stack system for 20% efficient silicon solar cells. In: The 31st IEEE Photovoltaic Specialists Conference. 2005: 872–876
55
P Ortega, M Vetter, S Bermejo, R Alcubilla. Very low recombination phosphorus emitters for high efficiency crystalline silicon solar cells. Semiconductor Science and Technology, 2008, 23(12): 125032
56
T Janssens, N E Posthuma, E van Kerschaver, Baer K t. Advanced phosphorous emitters for high efficiency Si solar cells. In: The 34th IEEE Photovoltaic Specialists Conference (PVSC). 2009: 000878–000882
57
A W Blakers, A H Wang, A M Milne, J H Zhao, A Green Martin. 22.8% efficient silicon solar cell. Applied Physics Letters, 1989, 55(13): 1363–1365
58
G Masetti, S Solmi, G Soncini. On phosphorus diffusion in silicon under oxidizing atmospheres. Solid-State Electronics, 1973, 16(12): 1419–1421
59
A Florakis, T Janssens, N Posthuma, J Delmotte, B Douhard. Simulation of the phosphorus profiles in a c-Si solar cell fabricated using POCl3 diffusion or ion implantation and annealing. Energy Procedia, 2013, 38: 263–269
60
B Hallam, S Wenham, C M Chong, A Sugianto, L Mai. Record large-area p-type CZ production cell efficiency of 19.3% based on LDSE technology. IEEE Journal of Photovoltaics, 2011, 1(1): 43–48
61
E Lee, H Lee, J Choi, D Oh, J Shim. Improved LDSE processing for the avoidance of overplating yielding 19.2% efficiency on commercial grade crystalline Si solar cell. Solar Energy Materials and Solar Cells, 2011, 95(12): 3592–3595
62
I B Cooper, K Tate, A F Carroll, K R Mikeska, R C Reedy. Low resistance screen-printed Ag contacts to POCl3 emitters with low saturation current density for high efficiency Si solar cells. In: Photovoltaic Specialists Conference (PVSC). 2012: 003359–003364
63
M J Kerr, A Cuevas. General parameterization of Auger recombination in crystalline silicon. Journal of Applied Physics, 2002, 91(4): 2473–2480
64
A Richter, S W Glunz, F Werner, J Schmidt, A Cuevas. Improved quantitative description of auger recombination in crystalline silicon. Physical Review B, 2012, 86(16): 165–202
65
A Schenk. Finite-temperature full random-phase approximation model of band gap narrowing for silicon device simulation. Journal of Applied Physics, 1998, 84(7): 3684–3695
66
E K Banghart, J L Gray. Extension of the open-circuit voltage decay technique to include plasma-induced bandgap narrowing. IEEE Transactions on Electron Devices, 1992, 39(5): 1108–1114
67
P P Altermatt, A Schenk, F Geelhaar, G Heiser. Reassessment of the intrinsic carrier density in crystalline silicon in view of band-gap narrowing. Journal of Applied Physics, 2003, 93(3): 1598–1604
68
H Mäckel, K Varner. On the determination of the emitter saturation current density from lifetime measurements of silicon devices. Progress in Photovoltaics: Research and Applications, 2013, 21(5): 850–866
69
P M Fahey, P Griffin, J Plummer. Point defects and dopant diffusion in silicon. Reviews of Modern Physics, 1989, 61(2): 289–384
70
A Dastgheib-Shirazi, M Steyer, G Micard, H Wagner. Effects of process conditions for the n+-emitter formation in crystalline silicon. In: Photovoltaic Specialists Conference (PVSC). 2012: 001584–001589
71
J C C Tsai. Point defect generation during phosphorus diffusion in silicon I. Journal of the Electrochemical Society, 1987, 134(6): 1508–1518
72
B Min, H Wagner, A Dastgheib-Shirazi, A Kimmerle, Ku H rz. Heavily doped Si:P emitters of crystalline Si solar cells: recombination due to phosphorus precipitation. physica status solidi (RRL) – Rapid Research Letters, 2014, 8(8): 680–684
73
B Min, H Wagner, P P Altermatt, Dastgheib-Shiraz A i. Limitation of industrial phosphorus-diffused emitters by SRH recombination. Energy Procedia, 2014, 55: 115–120
74
P F Schmidt, R Stickler. Silicon phosphide precipitates in diffused silicon. Journal of the Electrochemical Society, 1964, 111(10): 1188–1189
75
Y Komatsu, A H G Vlooswijk, A F Stassen, P Venema, C Meyer. Sophistication of doping profile manipulation-emitter performance improvement without additional process step. In: The 25th European Photovoltaic Solar Energy Conference and Exhibition-5th World Conference on Photovoltaic Energy Conversion. Valencia, Spain, 2010, 6: 10
