Amorphous silicon

About: Amorphous silicon is a research topic. Over the lifetime, 26777 publications have been published within this topic receiving 423234 citations.

Surface nanostructuring by nano-/femtosecond laser-assisted scanning force microscopy

Abstract: Surface nanostructuring with lateral resolutions beyond the capabilities of conventional optical lithography techniques was demonstrated in this study. Various nanoscopic surface features, such as grids, craters, and curves, were produced on thin metal and semiconductor films and bulk silicon by using the enhanced electric field underneath a proximity scanning probe tip irradiated with a laser beam. Nanoscale melting and crystallization of amorphous silicon films illustrates the capacity of the present scheme to provide an effective nanolaser source. Numerical simulations yield insight into the spatial distribution of the enhanced field intensity underneath the tip and associated physical phenomena. Calculations of the temperature distribution in the microprobe tip and possible tip expansion show that the main reason for the highly localized nanostructuring achieved with this technique is the enhancement of the electric field in the tip–sample gap. Possible applications of the developed nanostructuring process are anticipated in various nanotechnology fields.

Observation of memory effect in germanium nanocrystals embedded in an amorphous silicon oxide matrix of a metal-insulator- semiconductor structure

Abstract: The memory effect of a trilayer structure (rapid thermal oxide/Ge nanocrystals in SiO2/sputtered SiO2) was investigated via capacitance versus voltage (C–V) measurements. The Ge nanocrystals were synthesized by rapid thermal annealing of the cosputtered Ge+SiO2 films. The memory effect was manifested by the hysteresis in the C–V curve. Transmission electron microscope and C–V results indicated that the hysteresis was due to Ge nanocrystals in the middle layer of the trilayer structure.

Computer model of tetrahedral amorphous diamond.

Abstract: We computer generate a model of amorphous diamond using the Wooten-Weaire method, with fourfold coordination everywhere. We investigate two models: one where four-membered rings are allowed and the other where the four-membered rings are forbidden; each model consisting of 4096 atoms. Starting from the perfect diamond crystalline structure, we first randomize the structure by introducing disorder through random bond switches at a sufficiently high temperature. Subsequently, the temperature is reduced in stages, and the topological and geometrical relaxation of the structure takes place using the Keating potential. After a long annealing process, a random network of comparatively low energy is obtained. We calculate the pair distribution function, mean bond angle, rms angular deviation, rms bond length, rms bond-length deviation, and ring statistics for the final relaxed structures. We minimize the total strain energy by adjusting the density of the sample. We compare our results with similar computer-generated models for amorphous silicon, and with experimental measurement of the structure factor for (predominantly tetrahedral) amorphous carbon.

Growth of Large-Scale and Thickness-Modulated MoS2 Nanosheets

Abstract: Two-dimensional MoS2 is a promising material for next-generation electronic and optoelectronic devices due to its unique electrical and optical properties including the band gap modulation with film thickness. Although MoS2 has shown excellent properties, wafer-scale production with layer control from single to few layers has yet to be demonstrated. The present study explored the large-scale and thickness-modulated growth of atomically thin MoS2 on Si/SiO2 substrates using a two-step sputtering–CVD method. Our process exhibited wafer-scale fabrication and successful thickness modulation of MoS2 layers from monolayer (0.72 nm) to multilayer (12.69 nm) with high uniformity. Electrical measurements on MoS2 field effect transistors (FETs) revealed a p-type semiconductor behavior with much higher field effect mobility and current on/off ratio as compared to previously reported CVD grown MoS2-FETs and amorphous silicon (a-Si) thin film transistors. Our results show that sputter–CVD is a viable method to synthes...