Self-assembled silicon nanocrystal arrays for photovoltaics

Abstract

Silicon nanocrystals (Si NCs) are a promising candidate for the top cell of Si tandem solar cells since their bandgap exceeds that of bulk silicon and can be tuned by adjusting nanocrystal size. Due to this effect, size control is required to maintain a uniform bandgap throughout a Si NC film. This can be achieved by annealing superlattices of Si-rich and stoichiometric dielectrics. This paper reviews the progress that has been made using host matrices SiO2, Si3N4, and SiC. Si NCs in SiO2 show excellent NC size and shape control and strong quantum-confinement-related photoluminescence, however electrical conductivity is poor. Ordering and size control is also obtained in Si3N4, but conclusive evidence of quantum confinement is lacking. Preparing ordered but separated Si NCs in SiC is difficult, but the narrow parameter space in which this is possible has been elucidated, good electrical conductivity was obtained, and functioning single-junction and tandem cells have been produced. Si NC formation can now be well-controlled in all three materials, and the key weaknesses for photovoltaics have been identified to be the electrical conductivity of SiO2, and defect density for Si3N4 and SiC. Addressing these is expected to lead to competitive Si tandem solar cells

Room-temperature single dopant atom quantum dot transistors in silicon, formed by field-emission scanning probe lithography

“…3(b)). Further sources for tunnelling sites are any Si rich regions within the SiO2, forming Si nanocrystals (blue circles in neck region) embedded within the SiO2 [50], and these may or may not contain P atoms.…”

Silicium‐Nanokristalle und Silicium‐Polymer‐Hybridmaterialien: Synthese, Oberflächenmodifikation und Anwendungen

“…Da vor kurzem diverse Übersichtsartikel zu fundamentalen Entwicklungen von SiNKs in Bioanwendungen, Kernspintomographie und Photovoltaikanwendungen verçffentlicht wurden, werden diese Anwendungen in diesem Aufsatz nicht näher betrachtet. [24,[76][77][78][79] Im Folgenden soll vielmehr auf neue Entwicklungen der SiNKs als aktive Materialien in Batterieelektroden, Sensoren und Dioden, wie auch als Katalysatoren eingegangen werden.…”

Influence of 20 MeV electron irradiation on the optical properties and phase composition of SiOx thin films

“…4 Silicon nanoparticles have been studied actively in recent years because they are promising for application in various types of semiconductor devices, such as MOS based nonvolatile memories [5][6][7] and third generation solar cells. [8][9][10][11][12] We have shown that MOS structures with silicon nanocrystals are also promising for detectors of ionizing radiation. 13,14 Most frequently, Si nanoparticles are grown by high temperature thermal annealing of nonstoichiometric silicon oxides, but electron or ion beams irradiation has also been applied as a tool for growing and processing Si nanoparticles.…”