In this letter, we report on the formation, of copper-germanide/germanium nanowire (NW) heterostructures with atomically sharp interfaces. The copper-germanide (Cu3Ge) formation process is enabled by a chemical reaction between metallic Cu pads and vapor-liquid-solid (VLS) grown Ge-NWs. The atomic scale aligned formation of the Cu3Ge segments is controlled by in situ SEM monitoring at 310 degrees C thereby enabling length control of the intrinsic Ge-NW down to a few nanometers. The single crystal Cu3Ge/Ge/Cu3Ge heterostructures were used to fabricate p-type Ge-NW field effect transistors with Schottky Cu3Ge source/drain contacts. Temperature dependent I /V measurements revealed the metallic properties of the Cu3Ge contacts with a maximum current density of 5 x 10(7) A/cm2. According to the thermoionic emission theory, we determined an effective Schottky barrier height of 218 meV.

Electron beam induced deposition is among the most prospective methods for size- and position-controllable nanofabrication of three-dimensional structures. Direct-write maskless nanostructure fabrication was performed with a scanning electron microscope. Three-dimensional iron structures were obtained by locally confined electron induced dissociation of an iron carbonyl (Fe(CO)5) precursor. Vertical nanopillars consisting of Fe with O and C contaminations were deposited. Two different growth regimes—electron induced growth and autonomous growth—were observed. The precursor pressure was shown to have a significant influence on the growth mode.

A new beam-assisted process for removing silicon from a surface in the nanometer scale in a conventional scanning electron microscope is presented. This approach is based on focused electron beam induced etching with pure chlorine gas being used as the precursor. In contrast to the established etching process using a focused ion beam (with or without the addition of a precursor), no amorphization and gallium implanting of the substrate takes place. The observed low etch rates facilitate removal with sub-nanometer precision. No spontaneous etching of silicon as in the case of xenon difluoride was observed. Etch rates of up to 4 nm min( - 1) could be achieved as well as a minimum feature size of below 80 nm. The effect of etching parameters like electron beam energy, electron beam accelerating voltage or pixel spacing were systematically examined. Finally, the underlying etching mechanism in terms of secondary electron interactions and precursor replenishment is discussed.

In any scanning electron microscope (SEM) organic contamination of the vacuum chamber leads to undesired material deposition resulting in artifacts in imaging or compromises focused electron beam induced processes like etching (FEBIE) [S. Matsui and K. Mori, Appl. Phys. Lett 51, 1498 (1987)] or deposition (FEBID) [S. Matsui and K. Mori, J. Vac. Sci. Technol. B 4, 299 (1986); W. F. van Dorp and C. W. Hagen, J. Appl. Phys. 4, 081301 (2008)]. This effect can also be used on purpose as a method to evaluate the contamination level of a SEM. With a standardized process for controlled deposition from residual gas, a method to evaluate the contamination level of an electron microscope quantitatively and reproductively was developed. Additionally, this method not only allows monitoring the contamination level of a SEM over its lifetime. Also the impact of various deposition parameters on the extent of contamination deposition has been investigated systematically. This method also allows comparing the status of different tools. A comparison of three different SEM tools of different vendors and with different fields of application is demonstrated.

A new approach using focused electron beam induced deposition (FEBID) to deposit catalyst particles is reported for the synthesis of single crystalline silicon nanowires (SiNWs) grown by low pressure chemical vapor deposition (LPCVD). The FEBID deposited gold dot arrays fabricated from an acac-Au(III)-Me(2) precursor were investigated by AFM and EDX. The depositions were found to form a sharp tip and a surrounding halo and consist of only 10 at.% Au. However, SiNWs could be synthesized on the deposited catalyst using the vapor-liquid-solid (VLS) method with a mixture of 2% SiH(4) in He at 520 °C. NW diameters from 30 nm up to 150 nm were fabricated and the dependency of the NW diameter on the FEBID deposition time was observed. TEM analysis of the SiNWs revealed a [110] growth direction independent of the NW diameter. This new method provides a maskless and resistless approach for generating catalyst templates for SiNW synthesis on arbitrary surfaces.