Scanning electrochemical microscopy (SECM) was used to investigate the effect of ion bombardment on thin films of the conducting polymers poly[3-ethoxy-thiophene] (PEOT) and poly[ethylenedioxy-thiophene] (PEDT). Bombardment with Ar+-ions converts the topmost 30 nm thick layer to an essentially insulating material. SECM approach curves as well as two dimensional scans prove the existence of regions of different conductivity within the irradiated regions that did not show a significant dependence on ion dosage. PEDT layers patterned by ion bombardment through microscopic masks are investigated as prototypes of miniaturized printed circuit boards that can be formed by galvanic copper deposition onto conducting PEDT. Defects in conducting polymer patterns were analyzed by SECM imaging before any deposition of copper. Appropriate representations of SECM images for the evaluation of this technologically important question are discussed.

Micropatterns of the enzymes glucose oxidase (GOx) and horseradish peroxidase (HRP) have been formed on polycrystalline gold and glass surfaces using different soft-lithographic approaches. The patterns have been analyzed by noncontact scanning force microscopy. The activities of the immobilized patterns were probed with local resolution by scanning electrochemical microscopy. The following approaches have been tested:  (i) microcontact printing of octadecanethiol on gold, followed by chemisorption of cystaminium chloride and incubation of a mixture of HRP and glutaraldehyde to form a patterned cross-linked and grafted enzyme gel; (ii) microcontact printing of octadecanethiol on gold followed by chemisorption of HRP into which an thiol group had been introduced by modification with S-acetylthioglycolic acid-N-succinimidyl ester; (iii) application of a mixture of GOx with N-(3-dimethylaminopropyl)-N‘-ethylcarbodiimide hydrochloride (EDAC) to a stamp and contact with an aminated glass surface; (iv) delivery of a mixture of GOx with EDAC through microscopic open channels in a block of poly(dimethylsiloxane) pressed against an aminated glass surface. Satisfying contrast in enzymatic activity and high local enzyme activities were achieved by the modification of the gold surfaces. A general advantage of this monolayer system is the speed with which the binding of thiols to gold occurs. Therefore, the patterning step can be carried out with short contact times and the enzyme incubation can be made under controlled conditions in a moisture chamber. Approach ii offers the special advantage of reducing the number of process steps to two (stamping and application of thiolated enzyme), making it suitable for building up more complex structures formed by a sequence of structuring steps.

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Well-controlled fabrication of dislocation networks in Si using direct wafer bonding opens broad possibilities for nanotechnology applications. Concepts of dislocation-network-based light emitters, manipulators of biomolecules, gettering and insulating layers, and three-dimensional buried conductive channels are presented and discussed. A prototype of a Si-based light emitter working at a wavelength of about 1.5 microm with an efficiency potential estimated at 1% is demonstrated.

Metal-assisted chemical etching (MacEtch) has been established as a low-cost, benchtop, and versatile method for large-scale fabrication of semiconductor nanostructures and has been heralded as an alternative to conventional top-down approaches such as reactive-ion etching. However, extension of this technique to ternary III-V compound semiconductor alloys and heteroepitaxial systems has remained relatively unexplored. Here, Au-assisted and inverse-progression MacEtch (I-MacEtch) of the heteroepitaxial InGaP/GaAs material system is demonstrated, along with a method for fabricating suspended InGaP nanofoils of tunable thickness in solutions of hydrofluoric acid (HF) and hydrogen peroxide (HO). A comparison between Au- and Cr-patterned samples is used to demonstrate the catalytic role of Au in the observed etching behavior. Vertical etch rates for nominally undoped, p-type, and n-type InGaP are determined to be ∼9.7, ∼8.7, and ∼8.8 nm/min, respectively. The evolution of I-MacEtch in the InGaP/GaAs system is tracked, leading to the formation of nanocavities located at the center of off-metal windows. Upon nanocavity formation, additional localized mass-transport pathways to the underlying GaAs substrate permit its rapid dissolution. Differential etch rates between the epilayer and substrate are exploited in the fabrication of InGaP nanofoils that are suspended over micro-trenches formed in the GaAs substrate. A model is provided for the observed I-MacEtch mechanism, based on an overlap of neighboring injected hole distribution profiles. The nanofabrication methodology shown here can be applied to various heteroepitaxial III-V systems and can directly impact the conventional processing of device applications in photonics, optoelectronics, photovoltaics, and nanoelectronics.