Correlation between Al grain size, grain boundary grooves and local variations in oxide barrier thickness of Al/AlOx/Al tunnel junctions by transmission electron microscopy

A thickness variation of only one Ångström makes a significant difference in the current through a tunnel junction due to the exponential thickness dependence of the current. It is thus important to achieve a uniform thickness along the barrier to enhance, for example, the sensitivity and speed of single electron transistors based on the tunnel junctions. Here, we have observed that grooves at Al grain boundaries are associated with a local increase of tunnel barrier thickness. The uniformity of the barrier thickness along the tunnel junction thus increases with increasing Al grain size. We have studied the effect of oxidation time, partial oxygen pressure and also temperature during film growth on the grain size. The implications are that the uniformity improves with higher temperature during film growth.

A method for producing site-specific TEM specimens from low contrast materials with nanometer precision

A method that enables high precision extraction of transmission electron microscope (TEM) specimens in low contrast materials has been developed. The main idea behind this work is to produce high contrast markers on both sides of and close to the area of interest. The markers are filled during the depositing of the protective layer. The marker material can be of either Pt or C depending on which one gives the highest contrast. It is thereby possible to distinguish the location of the area of interest during focused ion beam (FIB) milling and ensure that the TEM sample is extracted precisely at the desired position. This method is generally applicable and enables FIB/scanning electron microscope users to make high quality TEM specimens from small features and low contrast materials without a need for special holders. We explain the details of this method and illustrate its potential by examples from three different types of materials.

Severe gemcitabine-induced capillary-leak Syndrome mimicking cardiac failure in a patient with advanced pancreatic cancer and high-risk cardiovascular disease

Pancreatic adenocarcinoma is the fourth most common cause of cancer-related mortality in the developed world. The nucleoside analogue gemcitabine is established standard therapy for advanced disease. Gemcitabine can occasionally cause non-dose-dependent pulmonary toxicity, and the systemic complication of capillary-leak syndrome, which may mimic cardiogenic pulmonary oedema. Here, we present a case of capillary-leak syndrome in a patient with pancreatic cancer treated with gemcitabine, with a past history of severe cardiovascular dysfunction and coronary arteriosclerosis.