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Presents a study which defined nanometer scale features on GaAs/AlGaAs heterostructure surfaces by electron beam patterning. Experimental procedures; Experimental results and discussion; Discussion on nanowire fabrication.

Presents a study which examined the damage caused by low-voltage helium and argon plasmas on an inverted heterostructure. Damage mechanism responsible for carrier loss; Factor attributed to the subsequent carrier increase seen for the argon case; Discussion of the experimental results.

We have devised and demonstrated a novel technique for fabricating structures with nanometer scale features in semiconductor heterostructures. The technique is based on definition of nanometer scale patterns by submicron trenches in a GaAs-AlGaAs heterostructure. The depletion of free carriers below the trenches gives rise to very strong electrostatic confinement. This technique avoids the complications associated with the use of negative resist materials and lift-off techniques while minimizing the time required to expose densely packed patterns. Aharonov–Bohm rings fabricated using this technique exhibit interference oscillation larger than any reported previously. [ABSTRACT FROM AUTHOR]

Electron cyclotron resonance and radio frequency reactive ion etching have been used to fabricate narrow n+-GaAs wires employing CCl2F2/He as the etch gas. A comparison of the induced sidewall damage is made using room-temperature conductivity measurements of the etched structures and the effect of overetching is investigated. In addition, preliminary analysis of low-temperature transport reveals that the amplitude of universal conductance fluctuations is extremely sensitive to sidewall damage. [ABSTRACT FROM AUTHOR]

We report the first successful incorporation of a pseudomorphic InGaAs base in a ballistic hot-electron device. The device, with a 28-nm-thick In0.15Ga0.85As base, had a collector-base breakdown voltage of 0.55 V and a maximum current transfer ratio of 0.89 at 4.2 K, considerably higher than the 0.75 in a comparable GaAs-base device. Electron energy spectroscopy measurements revealed that at least 30% of the injected electrons traversed the InGaAs base ballistically, causing a strong modulation in the injected currents into the quantized base. The Γ-L valley separation in the strained In0.15Ga0.85As was estimated to be about 410 meV. [ABSTRACT FROM AUTHOR]

We present new experimental results of ballistic electron transport through thin n+-GaAs layers. Measurements were done on tunneling hot-electron transfer amplifier devices composed of GaAs and AlGaAs layers. In devices with GaAs active regions (bases) of 300 and 800 Å, collisionless or ballistic transport was observed. By performing hot-electron energy spectroscopy we found that the collected ballistic distributions were similar in shape but differed in magnitude. This suggests the existence of a strong scattering mechanism which randomizes the otherwise ballistic electrons. The maximum differential current transfer ratio α was 0.9 in devices for which about 75% of the injected current traversed the base ballistically. The presence of ballistic transport has also allowed the measurement of the AlGaAs barrier height through observation of the onset of current collection in the devices. Barrier heights higher than those recently reported have been measured. In addition we show the effects of grading the collector barrier. The most noted effect in these cases was a higher transfer ratio. [ABSTRACT FROM AUTHOR]

Tunneling hot-electron transfer amplifier (THETA) devices, based on GaAs-AlGaAs heterojunctions, were fabricated and tested. Hot-electron transfer (α) through a 1100-Å base in excess of 70% was found at 4.2 K. This resulted in a corresponding current gain ( β) in a common emitter configuration of about 2.3. In the temperature range of 4.2–80 K and under constant biasing conditions, α was nearly temperature independent. Electron energy distributions for motion normal to the layers and electron total energy loss while traversing the device were estimated. Typical widths of the energy distributions were less than 200 meV, and both widths and energy peak positions were only slightly dependent on temperature and initial injection energy. [ABSTRACT FROM AUTHOR]