Amorphous silicon

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

Fabrication of a silicon micromachined capacitive microphone using a dry-etch process

Abstract: A silicon micromachined capacitive microphone has been fabricated on (100) silicon with PECVD silicon nitride as the diaphragm and backplate material. Amorphous silicon is used as the sacrificial layer and a dry-etch release method is used to free the diaphragm from the backplate. The dry-etch release method eliminates problems associated with the diaphragm and backplate sticking together, which often occurs due to capillary force of the rinse liquid with a wet-etch process. The fabricated microphone has a measured capacitance of 9.5 pF and an open-circuit sensitivity of 7 mV Pa−1 at a bias voltage of 6 V. This bias voltage is about 60% of the maximum allowed voltage that will electrostatically pull the diaphragm and backplate together. The measured frequency response of the microphone is flat within 4 dB from 100 Hz to 10 kHz and shows a gradual increase at higher frequencies.

High Ambipolar Mobility in a Highly Ordered Smectic Phase of a Dialkylphenylterthiophene Derivative That Can Be Applied to Solution‐Processed Organic Field‐Effect Transistors

Abstract: Since the 1990s, we have witnessed remarkable progress in organic semiconductor technology. [1] In particular, reasonably high carrier mobilities, exceeding those of amorphous silicon, were observed in thin-film transistors fabricated from a single crystal of rubrene. [2] In general, it is difficult to fabricate single crystals of aromatic compounds; therefore, zone-melt and Bridgeman crystal-growth [3] or vacuum crystal-growth techniques [4] are indispensable. Polycrystalline thin films are relatively easy to fabricate and suitable for practical devices. High carrier mobilities—of the order of 1 cm 2 V –1 s –1 —have been observed in field-effect transistor (FET) devices based on polycrystalline pentacene thin films. [5] However, defects and domain boundaries affect the carrier transport in aromatic polycrystalline thin films; therefore, the crystal growth under the vacuum process is rigorously controlled. [6] Device fabrication with a more practical solution process has been investigated. As well as conjugated polymers, [7] precursor methods in which thin films fabricated using soluble precursors are transformed to polycrystalline thin films by thermal treatment, [8] and solution-processable pentacene and anthradithiophene derivatives, which form polycrystalline thin films using a spin-coat method, have been investigated. [9] The field-effect mobilities in these studies are of the order of 10 –2 cm 2 , and the carrier mobility is increased up to 0.1 ≈ 1c m 2 V –1 s –1 by thermal treatment. [8,9] The optimum mobility is lower than those of the FET devices fabricated using vacuum deposition; the device characteristics strongly depend upon the film morphology, because the organic semiconductor thin films fabricated by the solution process have many defects and exhibit low carrier mobility.

Surface passivation of p-type crystalline Si by plasma enhanced chemical vapor deposited amorphous SiC x :H films

Abstract: Excellent passivation properties of intrinsic amorphous silicon carbide (a-SiCx:H) films deposited by plasma enhanced chemical vapor deposition on single-crystalline silicon (c-Si) wafers have been obtained. The dependence of the effective surface recombination velocity, Seff, on deposition temperature, total pressure and methane (CH4) to silane (SiH4) ratio has been studied for these films using lifetime measurements made with the quasi-steady-state photoconductance technique. The dependence of the effective lifetime, τeff, on the excess carrier density, Δn, has been measured and also simulated through a physical model based on Shockley–Read–Hall statistics and an insulator/semiconductor structure with fixed charges and band bending. A Seff at the a-SiCx:H/c-Si interface lower than 30 cm s−1 was achieved with optimized deposition conditions. This passivation quality was found to be three times better than that of noncarbonated amorphous silicon (a-Si:H) films deposited under equivalent conditions.

Semiconductor device having transistors with different orientations of crystal channel growth with respect to current carrier direction

Abstract: A silicon film is crystallized in a predetermined direction by selectively adding a metal element having a catalytic action for crystallizing an amorphous silicon and annealing. In manufacturing TFT using the crystallized silicon film, TFT provided such that the crystallization direction is roughly parallel to a current-flow between a source and a drain, and TFT provided such that the crystallization direction is roughly vertical to a current-flow between a source and a drain are manufactured. Therefore, TFT capable of conducting a high speed operation and TFT having a low leak current are formed on the same substrate.