Cigang Xu

Metal-free plasma-enhanced chemical vapor deposition of large area nanocrystalline graphene

This paper reports on large area, metal-free deposition of nanocrystalline graphene (NCG) directly onto wet thermally oxidized 150 mm silicon substrates using parallel-plate plasma-enhanced chemical vapor deposition. Thickness non-uniformities as low as 13% are achieved over the whole substrate. The cluster size of the as-obtained films is determined from Raman spectra and lies between 1.74 and 2.67 nm. The film uniformity was further confirmed by Raman mapping. The sheet resistance of 3.73 and charge carrier mobility μ of are measured. We show that the NCG films can be readily patterned by reactive ion etching. NCG is also successfully deposited onto quartz and sapphire substrates and showed % optical transparency in the visible light spectrum.

Growth mechanism of a hybrid structure consisting of a graphite layer on top of vertical carbon nanotubes

Graphene and carbon nanotubes (CNTs) are both carbon-basedmaterials with remarkable optical and electronic properties which, among others, may find applications as transparent electrodes or as interconnects inmicrochips, respectively. This work reports on the formation of a hybrid structure composed of a graphitic carbon layer on top of vertical CNT in a single deposition process. The mechanism of deposition is explained according to the thickness of catalyst used and the atypical growth conditions. Key factors dictating the hybrid growth are the film thickness and the time dynamic through which the catalyst film dewets and transforms into nanoparticles. The results support the similarities between chemical vapor deposition processes for graphene, graphite, and CNT.

Fast, Downstream Removal of Photoresist Using Reactive Oxygen Species From The Effluent of An Atmospheric Pressure Plasma Jet

In the semiconductor industry the plasma removal of photoresist (PR) between processing steps (so-called plasma ashing) is a critical issue in enabling the creation of advanced wafer architectures associated with the next generation of devices. We investigated the feasibility of a novel atmospheric-pressure plasma jet (APPJ) to remove PR. Our device operates at atmospheric pressure, eliminating the need for low-pressure operation used in conventional plasma ashing. Also, our method uses the downstream effluent of the source, avoiding issues relating to ion bombardment, a known hinderance to atomic precision manufacturing. Two-photon absorption laser induced fluorescence (TALIF) measurements of the system has shown that the PR removal rate is directly correlated with the atomic oxygen flux to the surface. The maximum removal rates achieved were 10 μm min−1, a factor of 100 improvement over typical low-pressure methods, while the quality of the etch, as assessed by attenuated total reflection fourier transform infrared spectroscopy, was found to be equal to low-pressure standards.