## Bonding ceramic sputter targets to metal holders

Published: Oct. 13, 2014

Ceramic sputter targets often need to be bonded to a metallic carrier. The better this bond provides mechanical, electrical and thermal contact, the better and longer the target works. This article describes indium soldering, the method that worked best during my PhD work where I used high-pressure oxygen sputtering extensively. The text is partly adapted from my PhD thesis.

## Variable resistor made by repeated steps of epitaxial deposition and lithographic structuring of oxide layers by using wet chemical etchants

Published: Jan. 22, 2013

Variable resistors were constructed from epitaxial $\ce{SrRuO3}$ (SRO), $\ce{La_{0.67}Sr_{0.33}MnO3}$ (LSMO) and $\ce{SrTiO3}$ layers with perovskite crystal structure. Each layer was patterned separately by lithographic methods. Optimized wet chemical etchants and several polishing steps in organic solvents allowed good epitaxy of subsequent layers, comparable to epitaxy on pristine substrates. Periodate as the oxidizing agent for SRO and iodide with ascorbic acid as the reducing agents for LSMO were used to attack these chemically resistant oxides. The final devices changed their conductance in a similar manner to previously described variable resistors that were defined with shadow masks.

## Non-volatile gated variable resistor based on doped $\ce{La2CuO_{4+\delta}}$ and $\ce{SrTiO3}$ heterostructures
Gated variable resistors were manufactured by depositing epitaxial heterostructures of doped $\ce{La2CuO_{4+$\delta$}}$ and $\ce{SrTiO3}$ layers. Their conductance change as function of write current $I$ and write time $t$ followed a simple empirical law of the form $\Delta G/G = C I^A t^B$. This behavior is in agreement with ionic transport that accelerates exponentially with electrical field strength.