Nanometre hole formation in MgO using electron beams

Does In form In-rich clusters in InGaN quantum wells?

“…If InGaN behaves in this way then Gerthsen and Kisielowski may be correct that damage-free electron micrographs of this material can be recorded. However, for other inorganic materials there appears to be no lower threshold electron beam current density for damage, which can also occur for incident electron energies as low as 40 keV [26]. If InGaN behaves in this way then damage-free microscopy is impossible.…”

Direct Measurements of the Radiolytic Transformation of Thin Films of Titanium Dioxide using EELS

“…This energy corresponds to sputtering thresholds for oxygen and magnesium of 240 and 330 keV respectively and in contrast, the low energy (40 keV) at which this effect occurs indicates that the binding energies for oxygen and magnesium must be less than 5.7 and 3.8 eV, respectively. Turner et al [1] have suggested that such low thresholds could arise if the surface were hydroxylated or if sputtering were occurring from low coordination sites on the surface of the growing hole.…”

“…In MgO, for instance, (001) faceted holes are observed to grow in from the electron exit surface at a rate proportional to beam fluxwhen thin foils of the material are irradiated at high current densities (106 -lOS A/m2) [1,2]. Although the directionality of the hole growth verifies the role of sputtering, a calculation of the energy necessary for this process rules out a simple momentum transfer.…”

Radiation damage processes affecting electron beam lithography of inorganic materials

“…The results of Hollenbeck and Buchanan also suggest that sputtering at the electron exit surface is in fact unnecessary for hole drilling, at least in the amorphous oxides, since they were able to repeatedly form high-quality holes in films supported at the electron exit side by 70 nm of SiO. Nevertheless, internal vacancy enhanced displacements may still play a role, and the recent observations of exit sputtering from crystalline Ti02 (Crozier et al 1990) and MgO (Turner et al 1990) indicate a need to further understand the momentum transfer processes.…”

“…Additionally, because radiolytic mechanisms are isotropic when it comes to momentum transfer, hole or void growth will occur symmetrically with respect to the electron entrance and exit surfaces, whereas any damage from knock-on displacement will be from atoms which have been knocked forward. Such determinations of hole morphology have been made by using stereo microscopy (e.g., Turner et al 1990) and by using separate secondary electron detectors at the electron entrance and exit surfaces (Crozier et al 1990).…”