A buried metal heterojunction bipolar transistor with submicron emitter was fabricated by electron-beam lithography. Two tungsten wires of 100 nm width, 100 nm height and 200 nm period were buried in the InP collector layer for the device with an emitter area of 0.3×1.5 μm. Total base-collector capacitance was reduced to about 22% of that calculated from the physical dimensions of conventional ...

Hydroxide ions that are initially buried within an ice film segregate to the ice film surface at elevated temperatures. This process was observed by conducting experiments with an ice film constructed with a bottom H(2)O layer and an upper D(2)O layer, with an excess of hydroxide ions trapped at the H(2)O/D(2)O interface as they were generated by Na hydrolysis. The transport of hydroxide ions f...

Neutron data from Mars Odyssey allow the determination of hydrogen stratigraphy in the framework of a simple 2-layer model, for latitudes equatorward of ±50°. On average, hydrogen is buried under a desiccated layer of thickness ~10 g/cm and a water-equivalent hydrogen (WEH) mass fraction in the 1% to 5% range. True hydrogen content of the Martian regolith below this relatively desiccated layer ...

An InGaAs/GaAs quantum well ~QW! disordering technique using AlAs native oxide and thermal annealing is presented. Unlike dielectric cap disordering, the AlAs native oxide can be placed close to quantum wells allowing for a spatially selective disordering deep within multilayer structures. The QW energy shifts and spatial control of the disordering were studied with photoluminescence and cathod...

The finite-difference time-domain (FDTD) method is used to simulate three-dimensional (3-D) geometries of realistic ground-penetrating radar (GPR) scenarios. The radar unit is modeled with two transmitters and a receiver in order to cancel the direct signals emitted by the two transmitters at the receiver. The transmitting and receiving antennas are allowed to have arbitrary polarizations. Sing...

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These complex systems often consist of mechanically graded structures that resist and respond to external normal and shear forces, and therefore protect underlying tissues from incurring any damage. As an example, the human epidermis consists of keratinizing epithelial cells—an elastic layer with low modulus—buried under a layer of dead cells, the stratum corneum , with higher modulus. The stra...

Qualitatively different thickness dependences have been observed in the glass transition temperature, Tg, of polystyrene (PS) films supported by hydrogen-passivated silicon (H-Si). It has been suggested that upon annealing at high temperatures in air, the polymer/substrate interface of these films (i.e., PS/Si), though buried underneath the PS layer, might be oxidized, rendering the films a dif...