Semiconductor lasers generate a significant amount of heat during operation, which causes a number of undesirable effects including increasing the current necessary for a given emission intensity and shorter device lifetime. Especially quantum cascade lasers (QCL) are sensitive to temperature, which results in a reduction in light emission or a cessation of laser operation. <br><br> <strong>Technology</strong><br> The QCL consists of an active zone which comprises a cascade structure and an insulating heat-dissipating zone which is laterally adjoined to the active zone. The active zone, which generates heat, is made from a semiconductor material with high crystalline order. The insulating heat-dissipating zone is made from an electrically insulating, heat conducting material which is identical to the semiconductor material of the active zone. The electrically insulating property of the heat-dissipating material is based on a reduced level of crystalline order compared to the semiconductor material of the active zone. The crystal defects result from growth on an underlying amorphous film. The pre-patterned substrate is made of a robust amorphous material and is able to withstand temperatures of growth and processing up to ~ 600 °C. The active regions are defined prior to epitaxy so that the processing is largely finished (except for metallization) when the structure emerges from the epitaxy reactor. <br><br>
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Automobiles increase the mobility of their users. However, their maneuverability is pushed to the limit by cramped inner city conditions. Those who need to...
Advance in biomedical imaging: The University of Würzburg's Biocenter has enhanced fluorescence microscopy to label and visualise up to nine different cell structures simultaneously.
Fluorescence microscopy allows researchers to visualise biomolecules in cells. They label the molecules using fluorescent probes, excite them with light and...
NASA's follow-on to the successful ICESat mission will employ a never-before-flown technique for determining the topography of ice sheets and the thickness of sea ice, but that won't be the only first for this mission.
Slated for launch in 2018, NASA's Ice, Cloud and land Elevation Satellite-2 (ICESat-2) also will carry a 3-D printed part made of polyetherketoneketone (PEKK),...
In the last decades, sea level has been rising continuously – about 3.3 mm per year. For reef islands such as the Maldives or the Marshall Islands a sinister picture is being painted evoking the demise of the island states and their cultures. Are the effects of sea-level rise already noticeable on reef islands? Scientists from the ZMT have now answered this question for the Takuu Atoll, a group of Pacific islands, located northeast of Papua New Guinea.
In the last decades, sea level has been rising continuously – about 3.3 mm per year. For reef islands such as the Maldives or the Marshall Islands a sinister...
The ‘Internet of Things’ is growing rapidly. Mobile phones, washing machines and the milk bottle in the fridge: the idea is that minicomputers connected to these will be able to process information, receive and send data. This requires electrical power. Transistors that are capable of switching information with a single electron use far less power than field effect transistors that are commonly used in computers. However, these innovative electronic switches do not yet work at room temperature. Scientists working on the new EU research project ‘Ions4Set’ intend to change this. The program will be launched on February 1. It is coordinated by the Helmholtz-Zentrum Dresden-Rossendorf (HZDR).
“Billions of tiny computers will in future communicate with each other via the Internet or locally. Yet power consumption currently remains a great obstacle”,...
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