Epitaxial GaInP/GaAs/Si Triple‐Junction Solar Cell with 25.9% AM1.5g Efficiency Enabled by Transparent Metamorphic Al_xGa_1−xAs_yP_1−y Step‐Graded Buffer Structures

Abstract

III–V/Si multi‐junction solar cells are potential successors to the silicon single‐junction cell due to their efficiency potential of up to 40% in the radiative limit.[1] Herein, latest results of epitaxially integrated GaInP/GaAs/Si triple‐junction cells are presented. To reduce parasitic absorption losses, which have limited the current density in the Si bottom cell in the previous devices, transparent AlxGa1–xAsyP1–y step‐graded metamorphic buffers are investigated. Compared with previous GaAsyP1–y step‐graded buffers, the transmittance is enhanced significantly, while no significant impact on the threading dislocation density is observed. Implemented into a new triple‐junction solar cell, an increase in short‐circuit current density from 10.0 to 12.2 mA cm−2 is achieved, leading to a new record conversion efficiency of 25.9% under AM1.5g conditions.

Crystal Phase Control during Epitaxial Hybridization of III‐V Semiconductors with Silicon

“…Among "More-than-Moore" strategies, the integration of optical devices with Silicon has attracted much attention. Indeed, the development of efficient light-emitting, energyharvesting, or light-engineering systems on silicon not only holds several advantages for the development of today's technologies (e.g., silicon photonics, [2][3][4] photovoltaics, [5] or sensors [6,7] ) but it could also open novel paradigms in photonics, computing or energy harvesting and storage applications (e.g., integrated quantum photonics, [8] all-optical neuromorphic computing, [9] or solar water splitting. [10] Silicon is however not naturally suitable for most optical applications, as it has an indirect band structure.…”

“…[25,27] Engineering the APBs generation and propagation at the early stages of the III-V growth on Si is thus the only way to fully benefit from the ultimate properties of integrated III-V semiconductors and a major prerequisite for the successful monolithic integration of III-V optoelectronic devices on Si photonic platforms [28,29] or III-V/Si energy harvesting devices. [5] In 1987, Kroemer [30] gave a first description of APBs generation, correlating the domain distribution and the local step structure of the initial Si surface. Theoretically, a Si surface only populated with biatomic steps does not allow the formation of APBs, as long as the III-V layer growth is uniformly initiated with the same group atoms (i.e., forming either III-Si bonds or V-Si bonds) and provided that the abrupt-interface atomic structure is strictly preserved during the first monoatomic layer deposition, without intermixing.…”

Negative Emissions as the New Frontier of Photoelectrochemical CO2 Reduction

“…The development of efficient and scalable photoelectrochemical carbon sinks will require advances in the area of multijunction solar cells, but also catalysis. The former aspect is being addressed also by the photovoltaics and solar hydrogen communities with progress for instance in III-V semiconductor integration with silicon [38] or perovskite-silicon tandems [39] and results will be directly transferable. Device prices of photovoltaics and PEC carbon sinks are expected to mutually benefit from scale-up.…”

GaAs/GaInP nanowire solar cell on Si with state-of-the-art Voc and quasi-Fermi level splitting

“…2 Mismatch in the lattice constant and thermal expansion coefficient between the materials renders the direct growth of high-quality III-V layers on Si difficult and leads to maximum efficiencies of 25.9%. 3 Owing to their small dimensions, III-V nanowires (NWs) can accommodate both lattice and thermal coefficient mismatches without the introduction of misfit dislocations at the interface. 4,5 Furthermore, NWs absorb a higher amount of light than their planar counterparts due to light trapping phenomena.…”

“…3. The latter would translate into an 8 meV increase in the qFl splitting values (kT ln(1.3), where T = 330 K).…”