High efficiency AlGaAs/Si monolithic tandem solar cell grown by metalorganic chemical vapor deposition

Abstract

The improvements of the AlGaAs solar cell grown on the Si substrate and the AlGaAs/Si tandem solar cell by metalorganic chemical vapor deposition have been investigated. The active-area conversion efficiency of the Al0.1Ga0.9As solar cell on the Si substrate as high as 12.9% has been obtained by improving the growth sequence and adopting an Al compositionally graded band emitter layer. A high efficiency monolithic AlGaAs/Si tandem solar cell with the active-area conversion efficiency of 19.9% and 20.6% (AM0 and 1 sun at 27 °C) under two-terminal and four-terminal configurations, respectively, is demonstrated.

III–V Multijunction Solar Cell Integration with Silicon: Present Status, Challenges and Future Outlook

“…Latticematched 2J InGaP/GaAs solar cells have been the key building block for today's most efficient 3J and quadruple junction (4J) III-V solar cells, with GaAs being predominantly used as the starting substrate. Hence, integration of GaAs-on-Si substrate was the initial and the natural choice for realizing a "GaAs-on-Si" virtual platform for the subsequent multijunction solar cell growth (Vernon et al 1986;Yamaguchi et al 1988;Soga et al 1995). More recently, approaches involving metamorphic graded buffers such as GaAsP and SiGe have gained a lot of attention for III-V/Si tandem solar cells (Grassman, Carlin, and Ringel 2010;Dimroth et al 2014;Diaz et al 2014;Yaung, Lang, and Lee 2014).…”

Design and mechanism of cost-effective and highly efficient ultrathin (< 0.5 μm) GaAs solar cells employing nano/micro-hemisphere surface texturing

“…for multijunction solar cell applications. [5][6][7][8] However, the high cost associated with the material itself and with the preparation of this 1000 nm thick high quality GaAs film, which is mainly due to the lack of appropriate low cost substrates having small lattice mismatch with GaAs, and also to the expensive deposition facilities strictly restrains the wide acceptance of the related solar electricity in civil utilities. 9 On the other hand, strong light reflection (> 30%) originating from the large refractive index difference between GaAs and the circumstance, e.g., air or vacuum for spacecraft applications demands the development of advanced antireflection coatings (ARCs) not only suppressing light reflection in a wide energy range but also with high stability and/or long-term endurance.…”

Integration of III-V materials on silicon substrates for multi-junction solar cell applications

“…The growth of III-V semiconductors on Si has been a long-sought desire by the microelectronic industry [4]. Particularly, in the PV field, the integration of III-V compounds on Si was intensively investigated in the 1990s, achieving good results [5]. However, the intensity of this research declined considerably in the late 1990s due to the difficulty in improving material quality and reproducibility.…”

“…In 1995, Soga et al achieved a record efficiency of about 20% AM0 [5] with a tandem solar cell based on AlGaAs/Si, using thermal cycle annealing (TCA) to allow the relaxation of the material. This technology has also produced excellent results in growing GaAsP on GaAs substrates [7]; however, it has been proved that the use of Si substrates involves much greater challenges, achieving efficiencies of only 9.2% AM0 for a tandem GaAs 0.7 P 0.3 / Si solar cell using TCA [8].…”

“…Figure 1. Iso-efficiency contour map, adapted from [5], that illustrates the theoretical efficiencies reachable with a DJSC grown on Si. The efficiency potential for GaAs1-xPx/Si cells for three different compositions is included.…”