The passivatedemitter, rearlocallydiffused (PERL) cells, fabricated in our laboratory, reach an efficiency of 24.0%, the highest value for any silicon‐based solar cell under terrestrial illumination. In an attempt to improve the rear surface passivation, which is usually obtained by a thermally grown oxide, we add a floating (i.e., noncontacted) pn junction at the rear surface, resulting in the passivatedemitter, rearfloatingpn junction (PERF) cell design. Although these cells exhibit record 1‐sun open‐circuit voltages of up to 720 mV, their efficiency is degraded by nonlinearities (‘‘shoulders’’) in the logarithmic IV curves. In order to understand and manipulate such nonlinearities, this paper presents a detailed investigation of the internal operation of PERF cells by means of numerical modelling based on experimentally determined device parameters. From the model, we derive design rules for optimum cell performance and develop a generalized argumentation that is suitable to compare the passivation properties of different surface structures. For example, the oxidized rear surface of the PERL cell is treated as an electrostatically induced floating junction in this approach and analogies to the diffused floating pn junction are drawn. Our simulations indicate that optimum rear surface passivation can be obtained in three different ways. (i) The floating junction of the PERF cell should be very lightly doped, resulting in a sheet resistivity of 5000 Ω/⧠, and losses due to shunt leaking paths between the pn junction and the rear metal contacts must be avoided. (ii) The rear surface of the PERL cell should be passivated by chemical vapor deposition of a silicon nitride film containing a larger positive interface charge density than exists in thermally grown oxides. (iii) An external gate can be added at the rear with low leakage currents and gate voltages of around 15 V.

1.
S. Y. Chiang, B. G. Carbajal, and G. Wakefield, in Proceedings of the 1st European Communities Photovoltaic Solar Energy Conference, Luxembourg, Sept. 1977, pp. 104–112.
2.
S. Y.
Chiang
,
B. G.
Carbajal
, and
G.
Wakefield
,
IEEE Trans. Electron. Devices
25
,
1405
(
1978
).
3.
O. von Roos and B. Anspaugh, in Proceedings of the 13th IEEE Photovoltaic Specialists Conference, Washington, D.C., June 1978, pp. 1119–1120.
4.
A. Luque, J. M. Ruiz, A. Cuevas, J. Eguren, and M. Agost, in Proceedings of the 1st European Communities Photovoltaic Solar Energy Conference, Luxembourg, Sept. 1977, pp. 269–277.
5.
A.
Luque
,
A.
Cuevas
, and
J.
Eguren
,
Solid State Electron.
21
,
793
(
1978
).
6.
R. M. Swanson, in Proceedings of the 17th IEEE Photovoltaic Specialists Conference, Kissimmee, FL, 1984, pp. 1294–1296.
7.
J. Zhao, A. Wang, P. P. Altermatt, S. R. Wenham, and M. A. Green, in 1st World Conference on Photovoltaic Energy Conversion, Waikoloa, HI, Dec. 1994, pp. 1477–80.
8.
A.
Wang
,
J.
Zhao
, and
M. A.
Green
,
J. Appl. Phys. Lett.
57
,
602
(
1990
).
9.
S. R. Wenham, S. J. Robinson, X. Dai, J. Zhao, A. Wang, Y.-H. Tang, A. Ebong, C. B. Honsberg, and M. A. Green, in 1st World Conference on Photovoltaic Energy Conversion, Waikoloa, HI, Dec. 1994, pp. 1278–1282.
10.
A. G.
Aberle
,
P. P.
Altermatt
,
G.
Heiser
,
S. J.
Robinson
,
A.
Wang
,
J.
Zhao
,
U.
Krumbein
, and
M. A.
Green
,
J. Appl. Phys.
77
,
3491
(
1995
).
11.
ISE Integrated Systems Engineering AG, Zurich, Switzerland, DESSIS 1.3.6: Manual, 1994.
12.
M. Y. Ghannam, in Proceedings of the 22nd IEEE Photovoltaic Specialists Conference, New York, New York, 1991, pp. 284–289.
13.
M. Y. Ghannam, E. Demesmaeker, J. Nijs, R. Mertens, and R. van Overstraeten, in Proceedings of the 11th European Photovoltaic Solar Energy Conference Montreux, Switzerland, 1992, pp. 45–8.
14.
P. Lölgen, C. Leguijt, L. A. Verhoef, W. C. Sinke, J. A. Eikelboom, R. A. Streeman, and H. H. C. de Moor, in Proceedings of the 12th European Photovoltaic Solar Energy Conference, Amsterdam, The Netherlands, 1994, pp. 544–547.
15.
P. Lölgen, Ph.D. thesis, University of Utrecht, The Netherlands, 1995.
16.
M. A. Green, Solar Cells (Prentice-Hall, New York, 1982), p. 70.
17.
A. G.
Aberle
,
S.
Glunz
, and
W.
Warta
,
J. Appl. Phys.
71
,
4422
(
1992
).
18.
A. G.
Aberle
,
S. W.
Glunz
,
A.
Stephens
, and
M. A.
Green
,
Prog. Photovoltaics
2
,
265
(
1994
).
19.
S. J.
Robinson
,
S. R.
Wenham
,
P. P.
Altermatt
,
A. G.
Aberle
,
G.
Heiser
, and
M. A.
Green
,
J. Appl. Phys.
78
,
4740
(
1995
).
20.
R. J.
Schwartz
,
J. L.
Bouknight
, and
M. S.
Worley
,
Int. Electron Devices Meeting
74
, (
1978
).
21.
A. G.
Aberle
,
S.
Glunz
, and
W.
Warta
,
Sol. Energy Mater. Sol. Cells
29
,
175
(
1993
).
22.
J.
Mandelkorn
and
J. H.
Lamneck
,
J. Appl. Phys.
44
,
4785
(
1973
).
23.
A.
Tuzzolino
,
Phys. Rev. A
134
,
205
(
1964
).
24.
V. S.
Vavilov
,
J. Phys. Chem. Solids
8
,
223
(
1959
).
25.
S.
Kolodinski
,
J. H.
Werner
,
T.
Wittchen
, and
H. J.
Queisser
,
Appl. Phys. Lett.
63
,
2405
(
1993
).
26.
P. P. Altermatt, Diploma thesis (physics), University of Constance, Germany, July 1994. Thesis project carried out at UNSW, Sydney, Australia.
27.
P. P. Altermatt, G. Heiser, A. Aberle, A. Wang, J. Zhao, S. J. Robinson, S. Bowden, and M. A. Green, Prog. Photovoltaics (to be published, 1996).
28.
G. Heiser and P. P. Altermatt, IEEE Trans. Comput.–Aided Des. (to be published).
29.
A. Cuevas, G. Giroult-Matlaowski, P. A. Basore, C. DuBois, and R. R. King, in 1st World Conference on Photovoltaic Energy Conversion, Waikoloa, HI, 1994, pp. 1446–1449.
30.
C.
Lombardi
,
S.
Manzini
,
A.
Saporito
, and
M.
Vanzi
,
IEEE Trans. Comput.–Aided Des.
7
,
1164
(
1988
).
31.
C.
Canali
,
G.
Majni
,
R.
Minder
, and
G.
Ottaviani
,
IEEE Trans. Electron Devices
22
,
1045
(
1975
).
32.
A.
Schenk
,
Solid State Electron.
35
,
1585
(
1992
).
33.
P. A. Basore and D. A. Clugston, in Proceedings of the 25th IEEE Photovoltaic Specialists Conference, Washington, D.C., 1996 (to be published).
34.
S.
Margalit
,
S.
Neugroschel
, and
A.
Bar-Lev
,
IEEE Trans. Electron Devices
19
,
861
(
1972
).
35.
R. S. R.
Hezel
and
K.
Blumenstock
,
J. Electrochem. Soc.
131
,
1679
(
1984
).
This content is only available via PDF.
You do not currently have access to this content.