Multi-beam scanning electron microscopy (mSEM) enables high-throughput, nano-resolution imaging of macroscopic tissue samples, providing an unprecedented means for structure-function characterization of biological tissues and their cellular inhabitants, seamlessly across multiple length scales. Here we describe computational methods to reconstruct and navigate a multitude of high-resolution mSEM images of the human hip. We calculated cross-correlation shift vectors between overlapping images and used a mass-spring-damper model for optimal global registration. We utilized the Google Maps API to create an interactive map and provide open access to our reconstructed mSEM datasets to both the public and scientific communities via our website www.mechbio.org. The nano- to macro-scale map reveals the tissue’s biological and material constituents. Living inhabitants of the hip bone (e.g. osteocytes) are visible in their local extracellular matrix milieu (comprising collagen and mineral) and embedded in bone’s structural tissue architecture, i.e. the osteonal structures in which layers of mineralized tissue are organized in lamellae around a central blood vessel. Multi-beam SEM and our presented methodology enable an unprecedented, comprehensive understanding of health and disease from the molecular to organ length scale.

We present a technique for the preparation of positively defined multiply connected electron waveguides on modulation-doped GaAs/AlGaAs heterostructures. This technique is based on a mix-and-match combination of electron-beam lithography (EBL) with standard photo lithography. Low-energy EBL on high-resolution negative-tone resist calixarene allows a nearly proximity-free positive definition of nanostructures with a minimum line width of about 25 nm. Subsequent to the EBL process the device leads and contacts are defined in photoresist with standard lithographic techniques. A single-step wet-chemical etch transfer enables the low-damage formation of isolated and multiply connected electron waveguides as well as large-area reservoirs. A 150 nm wide and 0.3 µm (1.2 µm) long quantum wire prepared by this technique shows quantized conductance with a maximum energy separation of 9.8 meV (10.9 meV) between the lowest one-dimensional subbands.

We have investigated two-dimensional electron gases (2DEGs) in inverted selectively doped GaAs/AlxGa1−xAs heterostructures fabricated by molecular-beam epitaxy (MBE) overgrowth of focused-ion-beam (FIB)-doped AlxGa1−xAs layers. In a first MBE step, the AlxGa1−xAs barrier was grown, before the sample was transferred to the FIB system. There, Si was implanted with 60 keV employing doses between 1×1012 and 1×1014 cm−2 and thereafter the sample was transferred back to the MBE system where the AlxGa1−xAs spacer as well as the GaAs top layer were grown. To protect the surface during the growth interruption, an amorphous As layer was used. Either an in situ annealing step before regrowth (30 s at 730 °C) or an ex situ thermal processing (30 s at 750 °C) after regrowth was used to remove the crystal damage due to the implantation. For the ex situ annealing step, we obtained mobilities up to 1.2×105 cm2/V s at 4.2 K after illumination whereas we observed mobilities up to 1.5×106 cm2/V s employing the in situ annealing step.

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