Single-crystal II-VI on Si single-junction and tandem solar cells

Abstract

CdTe is one of the leading materials used in solar photovoltaics. However, the maximum reported CdTe cell efficiencies are considerably lower than the theoretically expected efficiencies for the ∼1.48 eV CdTe band gap. We report a class of single crystal CdTe-based solar cells grown epitaxially on crystalline Si that show promise for enhancing the efficiency and greatly lowering the cost per watt of single-junction and multijunction solar cells. The current-voltage results for our CdZnTe on Si solar cells show open-circuit voltages significantly higher than previously reported for any II-VI cells and as close to the thermodynamic limit as the best III-V-based cells.

Study of Te aggregation at the initial growth stage of CdZnTe films deposited by CSS

“…Specimens for cross-sectional TEM analyses were prepared by cutting and mechanical grinding down to 50-60 µm, followed by Ar ion beam milling using a FISCHIONE 1010 Ion Mill to form small holes. All TEM images were taken down [1][2][3][4][5][6][7][8][9][10] zone axis with a Tecnai F30 G2 transmission electron microscope at 300 kV.…”

“…Cd 1−x Zn x Te (CdZnTe) films are of great importance for applications in solar cells [1,2], radiation detectors [3][4][5], and substrates for HgCdTe (MCT) epitaxy [6] as an alternative to those expensive and size limited bulk crystals. Great efforts have been made to grow high quality CdZnTe films [7][8][9][10][11][12][13].…”

Si/ZnxCd1-xTe heterostructures with different Zn contents: growth, electrical and photoelectrical properties

“…When manufacturing HS's with x < 0.1, the growth of Zn X Cd 1-X Te films can be carried out in the gas-dynamic flow mode (quasi-equilibrium conditions of condensation). The films obtained under such conditions have a uniform thickness over an area of about 20 cm 2 and represent large-block texture with a characteristic crystallite size of 1-2 microns. Along with structural uniformity, the films are homogeneous in a number of physical parameters: the variation of the electric and photoelectric parameters of individual elements in different parts of the plate does not exceed a few percent.…”

“…Currently, the greatest value of the conversion efficiency of solar energy was received on multijunction structures based on III-V compounds [1]. However, due to a number of technological and economic reasons, the multijunction structures that combine II-VI compounds with silicon are serious competition for the structures based on III-V compounds [2,3]. Among the possible combinations with silicon, of increased interest is a combination of silicon and cadmium telluride -a compound with an optimal set of physical parameters for photoelectric conversion of solar radiation [4].…”

Microstructure of Heteroepitaxial ZnTe Grown by Molecular Beam Epitaxy on Si(211) Substrates

“…Furthermore, ZnTe is also a device layer in recent solar cells based on II-VI semiconductors. 2,10 Knowledge of defects and interface structure is therefore essential for improving device performance. This paper analyzes the interface structure between ZnTe and the Si(211) substrate and discusses the origin of the formation of defects near the interface using high-resolution transmission electron microscopy (HRTEM).…”