Temperature Dependence of Carrier Extraction Processes in GaSb/AlGaAs Quantum Nanostructure Intermediate-Band Solar Cells

Abstract

From the viewpoint of band engineering, the use of GaSb quantum nanostructures is expected to lead to highly efficient intermediate-band solar cells (IBSCs). In IBSCs, current generation via two-step optical excitations through the intermediate band is the key to the operating principle. This mechanism requires the formation of a strong quantum confinement structure. Therefore, we focused on the material system with GaSb quantum nanostructures embedded in AlGaAs layers. However, studies involving crystal growth of GaSb quantum nanostructures on AlGaAs layers have rarely been reported. In our work, we fabricated GaSb quantum dots (QDs) and quantum rings (QRs) on AlGaAs layers via molecular-beam epitaxy. Using the Stranski–Krastanov growth mode, we demonstrated that lens-shaped GaSb QDs can be fabricated on AlGaAs layers. In addition, atomic force microscopy measurements revealed that GaSb QDs could be changed to QRs under irradiation with an As molecular beam even when they were deposited onto AlGaAs layers. We also investigated the suitability of GaSb/AlGaAs QDSCs and QRSCs for use in IBSCs by evaluating the temperature characteristics of their external quantum efficiency. For the GaSb/AlGaAs material system, the QDSC was found to have slightly better two-step optical excitation temperature characteristics than the QRSC.

Novel InGaSb/AlP Quantum Dots for Non-Volatile Memories

“…Further investigations were focused on the SAQD formation in III–V heterosystems with a higher E loc value. This trend has involved such well-known SAQDs system as GaSb/GaAs [ 19 , 20 , 21 ] and relatively novel heterosystems, for instance, GaSb/AlGaAs [ 22 , 23 ], GaSb/AlAs [ 24 ], InSb/AlAs [ 25 ], InGaAs/GaP [ 26 , 27 ], GaSb/GaP [ 28 , 29 ], InGaSb/GaP [ 30 , 31 ] and others, as discussed in [ 32 ]. The highest E loc value was obtained for GaSbP/GaP SAQDs (about 1.18 eV [ 29 ]), and it results in a storage time of about four days.…”

Modeling and simulation of GaAsPN / GaP quantum dot structure for solar cell in intermediate band solar cell applications

“…Introducing an intermediate energy band (IB) makes it possible to increase the absorption coefficient and the short-circuit current density J sc without decreasing the open-circuit voltage V oc . [6][7][8][9] GaAsPN materials have attracted much recent research attention; this alloy can be grown with an alterable bandgap staying lattice matched to Si. [10][11][12][13] These properties make this alloy a promising material for the manufacturing of quantum wells (QWs) and quantum dots (QDs).…”

“…[10][11][12][13] These properties make this alloy a promising material for the manufacturing of quantum wells (QWs) and quantum dots (QDs). [14][15][16] Shoji et al 9 confirmed that GaSb QDs and quantum rings (QRs) can be shaped on AlGaAs layers by Stranski-Krastanov growth and Assoaking techniques. They also investigated the suitability of multilayer quantum dot solar cells (QDSCs) for use in IBSCs.…”

“…An intermediate band solar cell (IBSC) is one of the new attractive representations for exceeding the efficiency of solar cells beyond the Shockley‐Queisser limit. Introducing an intermediate energy band (IB) makes it possible to increase the absorption coefficient and the short‐circuit current density J sc without decreasing the open‐circuit voltage V oc 6‐9 . GaAsPN materials have attracted much recent research attention; this alloy can be grown with an alterable bandgap staying lattice matched to Si 10‐13 …”

Nanostructured Materials for Solar Cell Applications

“…Qiang Zhang, Shengwen Hou and Chaoyang Li of Kochi University of Technology, Japan presented “Titanium Dioxide-Coated Zinc Oxide Nanorods as an Efficient Photoelectrode in Dye-Sensitized Solar Cells” [ 4 ]. Yasushi Shoji, Ryo Tamaki and Yoshitaka Okada of National Institute of Advanced Industrial Science and Technology, Japan and The University of Tokyo, Japan presented “Temperature Dependence of Carrier Extraction Processes in GaSb/AlGaAs Quantum Nanostructure Intermediate-Band Solar Cells” [ 5 ]. Panus Sundarapura, Xiao-Mei Zhang, Ryoji Yogai, Kazuki Murakami, Alain Fave and Manabu Ihara of Tokyo Institute of Technology, Japan and Univ Lyon, France presented “Nanostructure of Porous Si and Anodic SiO 2 Surface Passivation for Improved Efficiency Porous Si Solar Cells” [ 6 ].…”