Ge composition dependence of properties of solar cells based on multicrystalline SiGe with microscopic compositional distribution

Abstract

We present device performance of solar cells based on multicrystalline SiGe (mc-SiGe) bulk crystal with microscopic compositional distribution grown by the casting method. The average Ge composition was systematically changed in the range between 0% and 10%. A small addition of Ge to multicrystalline Si (mc-Si) was found to be very effective to increase the short-circuit current density without affecting the open-circuit voltage. As a consequence, the overall efficiency of a solar cell based on mc-SiGe was improved compared with that based on mc-Si. This result demonstrates that mc-SiGe is a promising candidate to replace mc-Si since it could achieve higher conversion efficiency without drastic increase of the production cost.

Growth and properties of SiGe multicrystals with microscopic compositional distribution and their applications for high-efficiency solar cells

“…In addition, external quantum efficiency was measured using tungsten and xenon lamps as light sources that pass through a monochromator. The spectroscopic response in the range between 1.15 and 1:4 mm for the SiGe multicrystal solar cells with microscopic compositional distribution was confirmed by Pan et al [4]. For the SiGe multicrystal solar cells with small amounts of Ge of 0.5% and 1%, quantum efficiency is enhanced in the longer-wavelength region up to 1:4 mm comparing with the Si solar cell without Ge.…”

“…efficiency of SiGe multicrystal solar cells with microscopic compositional distribution as a function of the average Ge composition. The shortcircuit photocurrent increases as the average Ge composition increases, because the absorption coefficient of the SiGe multicrystal with the average Ge composition of 5% is 1.2 times larger than that of the Si multicrystal at the wavelength of 500 nm [4]. However, the open-circuit voltage and the filling factor do not largely decrease as the average Ge composition increases within the compositional region below 5%.…”

“…These results imply that electrons generated in Ge-rich regions can effectively move to the p-n junction, and photocurrents can be generated without considerable recombination in Ge-rich regions. The internal quantum efficiency of the SiGe multicrystal solar cell is larger than that of the Si multicrystal solar cell over almost all the wavelength regions [4]. efficiency of SiGe multicrystal solar cells with microscopic compositional distribution as a function of the average Ge composition.…”

Hemisphere-shaped silicon crystal wafers obtained by plastic deformation and preparation of their solar cells

“…The shaped substrates were chemically treated in 1 HF:6 HNO 3 solution for 2 min at 25°C, and then etched in buffered HF solution for 2 min at 25°C before the solar cell process. 9 The nϩ layer of the solar cell was formed by rapid thermal annealing at 950°C for 30 min, after spinning coating of phosphorus-doped glass film (Ohka coat diffusion (OCD)) on all of the sample surface. The samples were then etched in buffered HF solution again to remove the residue of OCD film on the surfaces.…”

Investigation of strain relaxation mechanism in small SiGe clusters

“…Nakajima et al [46,47] have proposed multicrystalline SiGe with microscopic compositional distribution as a novel photovoltaic material. Their suggestion was tested by Pan et al [48]. They have investigated, in detail, the performance of solar cells based on mc-SiGe.…”