Regensburg 2002 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 11: Poster 1
HL 11.84: Poster
Montag, 11. März 2002, 17:00–19:30, Poster A
Photoluminescence studies of Amorphouss Silicon/Crystalline Silicon Hetero-Barriers — •Saioa Tardon, Rudolf Brueggemann, Thomas Unold, and Gottfried H. Bauer — Carl-von-Ossietzky Universitaet, Oldenburg, Fachbereich Physik, AG GRECO, Carl-von-Ossietzky strasse 9-11, 26129 Oldenburg
Amorphous silicon (n-type)/crystalline silicon (p-type) hetero-diodes with nominal efficiencies of about 12 % have been studied by room temperature photoluminescence at excitation wave lengths of 784 nm and AM1-equivalent photon fluxes Φ. The measurements were performed for different operation conditions, such as open circuit voltage (oc), short circuit current (sc), and maximum power point (mpp). Since optical generation as well as radiative recombination in the 30 nm thick a-Si:H window layer is negligible photoluminescence is exclusively attributed to transition in the crystalline Si wafer with rates rrad ∝ Ypl ∝ n p0 linearly dependent on minority concentration. The alteration of PL-yields by extraction of minority carriers from the diode can be qualitatively understood and quantitatively described via the one-dimensional steady state continuity equation. While PL-yields in short circuit only marginally depend on bulk lifetimes, and surface and interface recombination of our diodes, the excess carrier concentration in oc and consequently Ypl,oc are strongly governed by recombination losses in the bulk of c-Si and its interfaces. From log(Ypl,oc)-log(Φ) - plots we have derived diode ideality factors which are compared to those from voltage measurements; the experimentally observed ratio Ypl,oc/Ypl,sc yields strong evidence for interface defect densities larger than 1013 cm−2.