Amorphous silicon

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

Organic small molecule field-effect transistors with Cytop™ gate dielectric: Eliminating gate bias stress effects

Abstract: Organic field-effect transistors with unprecedented resistance against gate bias stress are described. The single crystal and thin-film transistors employ the organic gate dielectric Cytop™. This fluoropolymer is highly water repellent and shows a remarkable electrical breakdown strength. The single crystal transistors are consistently of very high electrical quality: near zero onset, very steep subthreshold swing [average: 1.3nFV∕(decadecm2)] and negligible current hysteresis. Furthermore, extended gate bias stress only leads to marginal changes in the transfer characteristics. It appears that there is no conceptual limitation for the stability of organic semiconductors in contrast to hydrogenated amorphous silicon.

Optical and photoconductive properties of discharge‐produced amorphous silicon

Abstract: Optical and photoconductive properties of discharge‐produced amorphous silicon (a‐Si) of the type used in efficient thin‐film solar cells have been studied as a function of a wide range of deposition conditions The optical absorption, optical band gap, photoconductivity, hydrogen content, and the characteristics of the Si‐H vibrational mode in a‐Si were determined Both substrate temperature in the range ∼200–400 °C and the type of discharge used are found to be important factors in determining the measured optical and photoconductive properties of a‐Si For films produced at substrate temperatures near 200 °C, dihydride bonding occurs, and the optical band gap is about 17 eV As the substrate temerature increases, monohydride bonding is favored, the optical band gap decreases, the optical absorption increases, and the photoconductive properties improve These properties are, in part, associated with the presence of bonded hydrogen For substrate temperatures between 300 and 400 °C, the photoconductive

Nickel induced crystallization of amorphous silicon thin films

Abstract: Nickel (Ni) induced crystallization of amorphous silicon (a-Si) has been studied by selective deposition of Ni on a-Si thin films. The a-Si under and near the Ni-covered regions was found to be crystallized after heat treatment at 500 °C from 1 to 90 h. Micro-Auger electron spectroscopy revealed that a large amount of Ni stayed in the region under the original Ni coverage, but no Ni was detected either in the crystallized region next to the Ni coverage or in the amorphous region beyond the front of the laterally crystallized Si. X-ray photoelectron spectroscopy revealed a nonuniform Ni distribution through the depth of the crystallized film under the original Ni coverage. In particular, a Ni concentration peak was found to exist at the interface of the crystallized Si and the buried oxide. It was found that a layer of 5-nm-thick Ni could effectively induce lateral crystallization of over 100 μm of a-Si, but the lateral crystallization rate was found to decrease upon extended heat treatment. Transmission e...

Fast-charging high-energy lithium-ion batteries via implantation of amorphous silicon nanolayer in edge-plane activated graphite anodes

Abstract: As fast-charging lithium-ion batteries turn into increasingly important components in forthcoming applications, various strategies have been devoted to the development of high-rate anodes. However, despite vigorous efforts, the low initial Coulombic efficiency and poor volumetric energy density with insufficient electrode conditions remain critical challenges that have to be addressed. Herein, we demonstrate a hybrid anode via incorporation of a uniformly implanted amorphous silicon nanolayer and edge-site-activated graphite. This architecture succeeds in improving lithium ion transport and minimizing initial capacity losses even with increase in energy density. As a result, the hybrid anode exhibits an exceptional initial Coulombic efficiency (93.8%) and predominant fast-charging behavior with industrial electrode conditions. As a result, a full-cell demonstrates a higher energy density (≥1060 Wh l−1) without any trace of lithium plating at a harsh charging current density (10.2 mA cm−2) and 1.5 times faster charging than that of conventional graphite. It is desirable to develop fast-charging batteries retaining high energy density. Here, the authors report a hybrid anode via incorporation of an implanted amorphous silicon nanolayer and edge-plane-activated graphite, which meets both criteria.

Electrical Properties of Amorphous Silicon Transistors and MIS‐Devices: Comparative Study of Top Nitride and Bottom Nitride Configurations

Abstract: The electrical properties of silicon nitride/amorphous silicon structures were investigated using thin film transistors (TFTs) and metal insulator semiconductor (MIS) devices employing either a top nitride (TN) or bottom nitride (BN) as gate insulator. The density of states (DOS) deduced from the subthreshold transfer characteristic of the TFTs is one to two orders of magnitude higher than that obtained from quasistatic C(V) measurements on the MIS structures. This difference is discussed by considering the different thickness of the a‐Si:H layers of the two devices and the role of a fixed charge at the rear interface. Both techniques indicate a DOS in BN devices which is only slightly lower than in TN devices, by less than a factor of two. The measured field effect mobility of BN TFTs is about 70% higher. The differences in the measured field effect mobility for TN and BN configuration are discussed and ascribed to the source and drain parasitic resistances. The conclusion is verified by the fabrication of a TN TFT with a pure phosphine rear surface treatment, which exhibits performance comparable to BN TFTs.