False-colored SEM image of an oxide field-effect transistor with a gate-length of ~ 70 nm (sample by Carsten Woltmann, PhD thesis).

Photograph of an oxide chip containing several hundred thousand LaAlO3 - SrTiO3 field effect transistors. The colors are caused by light interfering with the transistor arrays (Carsten Woltmann).

View into our pulsed-laser deposition system (target manipulator).

Photograph of a thermoelectronic energy converter in action.

Thermolelectronic generator built to analyze in-situ and under operating conditions the work functions of quantum material heterostructures grown in our pulsed laser deposition system.

Sketch of envisioned solid-state/liquid-state heterostructures. This cross section illustrates the freedom of design and advances achievable if microscopic volumes of liquids (colored) were integrated into heterostructures. In the liquid volumes, for example, ions may create electric double layers (center) or move across gaps (sketch at right).

Sketch illustrating the vision of a sample containing integrated, microscopic liquid volumes, as opposed to Fig 2. Different liquids patterned into distinct shapes may be placed onto the sample at well-determined locations and then overgrown by subsequent layers.

Illustration of a typical state-of-the-art sample setup used for ionic gating. A macroscopic drop of an electrolyte (blue) dropped onto the sample provides the gate liquid.

Optical microscopy image of a capacitor with integrated NaCl-H2O dielectric of ≈20 μm diameter (green arrow).

Photograph of a sample with 16 integrated capacitors after deposition of NaCl, before H2O deposition. The green arrows point to three of the capacitors (small bright dots).

Top: Optical microscopy images of a ZnO-field-effect transistors with integrated NaCl-H2O dielectrics (arrow). These transistors have channel lenghts l≈10–20 μm.
Bottom: Optical microscopy images of a chip containing 16 FETs.