Silicon Quantum Dots in a Dielectric Matrix for All-Silicon Tandem Solar Cells

Abstract

We report work progress on the growth of Si quantum dots in different matrices for future photovoltaic applications. The work reported here seeks to engineer a wide-bandgap silicon-based thin-film material by using quantum confinement in silicon quantum dots and to utilize this in complete thin-film silicon-based tandem cell, without the constraints of lattice matching, but which nonetheless gives an enhanced efficiency through the increased spectral collection efficiency. Coherent-sized quantum dots, dispersed in a matrix of silicon carbide, nitride, or oxide, were fabricated by precipitation of Si-rich material deposited by reactive sputtering or PECVD. Bandgap opening of Si QDs in nitride is more blue-shifted than that of Si QD in oxide, while clear evidence of quantum confinement in Si quantum dots in carbide was hard to obtain, probably due to many surface and defect states. The PL decay shows that the lifetimes vary from 10 to 70 microseconds for diameter of 3.4 nm dot with increasing detection wavelength.

Generalized rate-equation analysis of excitation exchange between silicon nanoclusters and erbium ions

“…Nanocluster lifetimes tend to be growth dependent and vary strongly with the degree of crystallinity of the clusters, their size, mean separation, the nature of the matrix surrounding them, and the presence of nonradiative deexcitation pathways. 23 For example, Cho et al demonstrated lifetimes between 2 and 60 s for 3.4 nm diameter clusters, 24 and implanted material can show lifetimes between Ͻ5 and 30 s. 25 In contrast, longer lifetimes have been reported in the region of 50-100 s, 26 and even as long as 500 s for noninteracting nanoclusters. 27 Clearly, an interpretation of the stretched exponential rise time data requires considerable care.…”

Silicon Nanocrystals as an Enabling Material for Silicon Photonics

“…However, the transport can be affected by the matrix in which the Si-nc embedded. It has been found that SiC and Si 3 N 4 matrices give lower barrier heights [105] and also longer distance between Si-ncs for significant wave function overlapping [158] than those of SiO 2 . The conductivity can also been improved by using a lateral multilayer Si-nc/SiO 2 structure [159].…”

Effect of Retrapping on Thermoluminescence Peak Intensities of Small Amorphous Silicon Quantum Dots

“…TL continues to be an active area of research because of its immense contribution in the fields of personal and environmental dosimetry, dating of archaeological artifacts, sediments and study of defects in solids [1]. In particular, light emission from silicon quantum dots has got recent attention because of its potential applications in the silicon-based optoelectronic devices [6][7][8][9][10]. There are different mechanisms of increasing the efficiency of the light emitting device.…”