No abstract

No abstract

No abstract

We demonstrate the direct transfer of graphene from Cu foil to rigid and flexible substrates, such as glass and PET, using as an intermediate layer a thin film of polyimide (PI) mixed with an aminosilane (3-aminopropyltrimethoxysilane) or only PI, respectively. While the dry removal of graphene by an adhesive has been previously demonstrated—being removed from graphite by scotch tape or from a Cu foil by thick epoxy (~20 µm) on Si—our work is the first step towards making a substrate ready for device fabrication using the polymer-free technique. Our approach leads to an article that is transparent, thermally stable—up to 350 °C—and free of polymer residues on the device side of the graphene, which is contrary to the case of the standard wet-transfer process using PMMA. Also, in addition to previous novelty, our technique is fast and easier by using current industrial technology—a hot press and a laminator—with Cu recycling by its mechanical peel-off; it provides high interfacial stability in aqueous media and it is not restricted to a specific material—polyimide and polyamic acids can be used. All the previous reasons demonstrate a feasible process that enables device fabrication.

No abstract

No abstract

The effects of a protective capping layer on the microstructure of ultrathin separation by implantation of oxygen ͑SIMOX͒ materials formed by ion implantation were studied using transmission electron microscopy. A set of SIMOX wafers were implanted at 65 keV in a dose range of 1.5 to 7.0 ϫ 10 17 O ϩ /cm 2 followed by a high temperature ͑1350°C͒ annealing with and without a protective cap. The lowest dose to form a continuous buried oxide ͑BOX͒ layer without Si islands at 65 keV is 2.0 ϫ 10 17 O ϩ /cm 2 without a protective cap and 2.5 ϫ 10 17 O ϩ /cm 2 with a protective cap. Above 2.5 ϫ 10 17 O ϩ /cm 2 under both annealing conditions, the BOX layer formed continuously but with Si islands present. The uncapped samples show slightly lower density of Si islands. Oxygen from the annealing ambient can diffuse in the uncapped samples through the thin top Si layer, which helps the BOX layer grow laterally and lower the Si island density. The density of defects in the top Si layer is also slightly lower in the uncapped samples because of the ability of Si interstitials to incorporate into the surface and the effective annihilation of extended defects during the final annealing step. The top Si layers of the uncapped samples are thinner than those of the capped samples due to surface thermal oxidation.The development of high quality ultrathin silicon-on-insulator ͑SOI͒ substrates is essential for the emerging submicrometer technology and fully depleted applications. SOI substrates have many advantages over bulk Si substrates for isolation, process simplicity, for short channel device performance, and for applications involving low power, high speed, high temperature, and radiation hardness. [1][2][3][4][5] Of the several SOI technologies, the most advanced is the synthesis of a buried oxide ͑BOX͒ layer by the separation by implanted oxygen ͑SIMOX͒ technique. 6 Conventionally, SIMOX wafers are produced by implanting high dose high energy oxygen ions ͑1.8 ϫ 10 18 O ϩ /cm 2 , 200 keV͒ into Si wafers. This process is expensive because it requires a long implantation time. In addition, the wafers produced by this technology contain a relatively high density of threading dislocations in the top Si layers. In order to overcome these problems, the low dose SIMOX technique was introduced. However, the low dose BOX layer is inferior to that of the high dose SIMOX in terms of electrical characteristics and reliability. Recently, it has been shown that the integrity of thin BOXs can be improved by annealing in a highly oxidizing ambient. 7 The same method has also been used to successfully produce thin film SIMOX wafers through surface oxidation. 8,9 However, a high production cost is incurred from the additional processing steps.A direct and cost-effective way to reduce the thickness of the top Si layer and the BOX layer is to decrease both the implantation energy and the oxygen dose. Reducing the implantation energy decreases the spread of the implanted ions which makes it possible to form a continuous BOX layer at lower doses whic...

No abstract