This article is cited in 24 papers

Semiconductor physics

Germanium subcells for multijunction GaInP/GaInAs/Ge solar cells

N. A. Kalyuzhnyy^a, A. S. Gudovskikh^b, V. V. Evstropov^a, V. M. Lantratov^a, S. A. Mintairov^a, N. Kh. Timoshina^a, M. Z. Shvarts^a, V. M. Andreev<sup>ab

a</sup> Ioffe Institute, St. Petersburg
^b St. Petersburg Academic University — Nanotechnology Research and Education Centre of the Russian Academy of Sciences (the Academic University)

Abstract: Photovoltaic converters based on $n$-GaInP/$n$–$p$-Ge heterostructures grown by the OMVPE under different conditions of formation of the $p$–$n$ junction are studied. The heterostructures are intended for use as narrow-gap subcells of the GaInP/GaInAs/Ge three-junction solar cells. It is shown that, in Ge $p$-tn junctions, along with the diffusion mechanism, the tunneling mechanism of the current flow exists; therefore, the two-diode electrical equivalent circuit of the Ge $p$–$n$ junction is used. The diode parameters are determined for both mechanisms from the analysis of both dark and “light” current-voltage dependences. It is shown that the elimination of the component of the tunneling current allows one to increase the efficiency of the Ge subcell by $\sim$1% with conversion of nonconcentrated solar radiation. The influence of the tunneling current on the efficiency of the Ge-based devices can be in practice reduced to zero at photogenerated current density of $\sim$1.5 A/cm$^2$ due to the use of the concentrated solar radiation.

Received: 07.06.2010
Accepted: 22.06.2010

 English version: Semiconductors, 2010, 44:11, 1520–1528

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