Photodiode Response in a CHNHPbI/CHNHSnI Heterojunction.

Here we report another surprising feature of the methylammonium metal halide material family, the phototunability of the diode response of a heterojunction made of CHNHPbI and its close relative, CHNHSnI. In the dark state the device behaves as a diode, with the Sn homologue acting as the "p" side. The junction is extremely sensitive to illumination.

Construction and characterization of a frequency-controlled, picometer-resolution, displacement encoder-actuator.

We have constructed an actuator/encoder whose generated displacement is controlled through the resonance frequency of a microwave cavity. A compact, 10-μm-range, digitally controlled actuator executing frequency-coded displacement with picometer resolution is described. We consider this approach particularly suitable for metrologic-precision scanning probe microscopy.