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We design and investigate numerically a Si-based deep-trench microstructure covered with continuous thin gold (Au) films. It breaks through the absorption limitation of Si material and greatly extends the near-infrared (NIR) absorption range to 1500 nm. By the simulated distributions of electric-field intensity, we observe clearly the excitation of surface plasmon polaritons and the standing wave resonance of plasmon cavity formed inside the deep trench, by which we explain the extending broadband NIR absorption well. We further discuss the influence of trench depth on the cavity mode and NIR absorption in detail. By combination of the proposed microstructures, it is a promising approach to realize an extending broadband and high NIR photoresponse in Si-based detectors. [ABSTRACT FROM AUTHOR]

A broadband near-infrared (NIR) absorption from 1200 to 2500 nm in Si substrate is investigated by Ag film deposition and subsequent thermal annealing. Under thermal annealing, Ag films can crack and shrink into Ag nanoparticles (NPs). Annealing temperature greatly affects the size, distribution status and morphology of Ag NPs, resulting in different NIR absorption. The influence of the size and distribution of Ag NPs on NIR absorption originated from localized surface plasmon resonance (LSPR) is theoretically simulated by a finite difference time domain method. The band width of LSPR belongs to different type Ag NPs are discussed. [ABSTRACT FROM AUTHOR]

We design a deep-trench microstructure covered with thin gold films to enhance near-infrared absorption of silicon material. This deep-trench microstructure exhibits a much higher absorption compared with plane nanoantenna arrays. We investigate its absorption enhancement in detail and find that the trench-shaped plasmonic waveguide greatly contributes an absorption enhancement by concentrating light effectively. Further, we clarify the influence of both trench depth and gold films covering on different positions of deep trench on the absorption. Finally, we use surface plasmon polaritons offered by plasmonic waveguide to explain well the significant enhancement of near-infrared absorption. [ABSTRACT FROM AUTHOR]

Abstract: Low-temperature micro-photoluminescence (PL) was performed for strained Si (sSi) films by 325nm-laser excitation at 8.5K. All of the sSi films were thicker than the penetration depth (d p) of the 325-nm line for Si. The dependence of the PL spectra on the strain condition was studied by comparing d p to the thickness of the strained part (t s), which varied in the sSi film plane. Under the condition t s > d p, the strained-part-related PL (PL-S) was observed, but not the unstrained-part-related PL (PL-US). Under the condition t s < d p, PL-US appeared and its intensity negatively depended on t s, while the intensity of PL-S positively depended on t s. Under the condition of a very small t s, PL-S was never observed. These phenomena were explained by exciton behaviors in sSi film with a band-gap distribution, and enable a deeper understanding of PL characteristics in a relatively large-scale sample with a depth distribution of strain. [Copyright &y& Elsevier]

Bottom-channel hole mobility was examined by a pseudo-metal-oxide-semiconductor field-effect transistors method for ultrathin SiGe-on-insulator (SGOI) and Ge-on-insulator (GOI), which were fabricated using Ge condensation by dry oxidation. By comparing samples with and without a top SiO2 layer, we investigated the influence of top surface passivation on bottom-channel hole mobility. Mobility degradation was found in an ultrathin SGOI/GOI layer without top SiO2 and became more serious with a decrease in the thickness of the SGOI/GOI layer, which strongly suggested that top surface passivation is necessary to evaluate accurate channel mobility. A 13-nm-thick GOI with passivation showed a high mobility value of 440 cm2/V s. [ABSTRACT FROM AUTHOR]

Highlights • A way to study the physical properties of sulfur hyperdoping layer is provided. • The interaction between the hyperdoping layer and microstructure is clarified. • Hyperdoping concentration and its existence state cause strong infrared absorption. • A electromagnetic localization plays a critical role to improve infrared absorption. Abstract We studied the infrared absorption of a top sulfur hyperdoping layer covering an fs-laser irradiated microstructured Si substrate. To clarify the hyperdoping concentration distributions, and to find out how the top hyperdoping layer affects infrared absorption from 1200 to 2000 nm, a continuous etching treatment was utilized. Then we interpreted the thermal stabilization of both infrared absorption and sulfur hyperdoping concentration. The fundamental cause for infrared-absorption degradation under thermal annealing was explained. Furthermore, we discussed in detail how the interaction between the top hyperdoping layer and surface microstructure contributed to the high infrared absorption by a series of theoretical simulations using a finite-difference time-domain method. A strong localization of an incident electromagnetic wave was observed around the top sulfur hyperdoping layer covering microstructured Si, which played a critical role in improving infrared absorption. The results in this paper are especially beneficial to the subsequent fabrication of photoelectric devices and infrared response improvement. [ABSTRACT FROM AUTHOR]