The surface, structural, and optical properties of InAs/InGaSb/AlSb mid-infrared lasers grown by molecular beam epitaxy have been systematically studied, respectively, by Nomarski differential interference contrast, high-resolution x-ray diffraction, and variable-temperature photoluminescence. It is found that the optimum growth temperature is between 400 and 450 °C, based on the calibrated transmission thermometry. In addition, the impact of interfacial bond type and Sb sources has been investigated. A 5.91 μm laser, grown with the optimal growth parameters, exhibits a maximum cw operating temperature of 210 K.

Optimum growth parameters for type-II infrared lasers

The unusual electrical, optical, magnetic, and chemical properties of metal colloids (better known in nowadays as metal nanoparticles, MNPs) have attracted increasing interest of scientists and technologists during the last decade. In fact, although Nanoscience and Nanotechnology are quite recent disciplines, there have already been a high number of publications that discuss these topics. [1-11] What is more, there are quite new high impact peer-reviewed journals especially devoted to these research fields and there is also a particular subject category “Nanoscience & Nanotechnology” in the Journal Citation Reports from Thomson Reuters.

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Bifunctional polymer-metal nanocomposite ion exchange materials

Transmission spectra of GaSb have been obtained over a temperature range from 10 to 470 °C. Using this information, transmission thermometry is applied to obtain accurate measurements of sample temperature during molecular beam epitaxy growth on GaSb substrates. A GaSb surface reconstruction transition is determined as a function of Sb flux and substrate temperature, establishing a laboratory-independent temperature standard.

Determination of temperature dependence of GaSb absorption edge and its application for transmission thermometry

We report a fabrication method for laterally confining the two-dimensional electrons in InAs/AlSb single quantum wells into artificially patterned conducting wires. The minimum wire width is demonstrated to be ∼30 nm, among the smallest reported to date. The confining potential is approximately square and abrupt, and that makes the electron’s spatial distribution in the transverse direction the same as the physical width of the wire. The conducting electrons have close proximity to the surface charges, thus there is always a reduction in the elastic mean free path when the wire width decreases. Despite the reduction in mean free path, we find that the phase coherence length is approximately 1 μm at 2.2 K, a factor of 30 larger than the minimum feature size.

Nanometer-size InAs/AlSb quantum wires: Fabrication and characterization of Aharonov-Bohm quantum rings

- Ion Exchange-Assisted Synthesis of Polymer Stabilized Metal Nanoparticles

A tunneling field-effect transistor with an ultrashort channel-length of 25 nm has been experimentally realized using InAs/AlSb heterostructures. The conduction between the source and the drain is through a sequential process, including tunneling and drift-diffusion mechanisms. According to its operating principle, the transistor is inherently free of the conventional short-channel effects. The results demonstrate a new scheme of building nanometer-scale transistors.

D. R. Stone

Papers

A tunneling field-effect transistor with 25 nm metallurgical channel length