We report on reflective electro-optic sampling measurements of TeraHertz emission from nanometer-gate-length InGaAs-based high electron mobility transistors. The room temperature coherent gate-voltage tunable emission is demonstrated. We establish that the physical mechanism of the coherent TeraHertz emission is related to the plasma waves driven by simultaneous current and optical excitation. A significant shift of the plasma frequency and the narrowing of the emission with increasing channel's current are observed and explained as due to the increase of the carriers density and drift velocity.T.

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The magnetic properties of Mn ultra-thin films epitaxially grown on (001) bcc Fe are studied by soft–X-ray magnetic circular dichroism. At room temperature, the Mn growth is two-dimensional without interdiffusion in Fe, as checked by RHEED and Auger spectroscopy. A net Mn magnetic moment is observed in the Mn thickness range up to 2 monolayers. We find that the Mn/Fe interfacial coupling is definitely ferromagnetic. In this range, the magnetic moment carried per Mn atom is found to be about 1.7 μB, which is much smaller than the value of 3 μB predicted for ferromagnetic Mn ultra-thin films.

With respect to more standard and more widely used inductive-heating, the resistivelyheated reactors offer the strong advantage of low cost, easy installation and low running constraints. Combined with an easy adaptation to the increasing size of wafers, this results in very strong advantages. This simple technique was mainly restricted to the growth of small size samples for academic purpose [1]. In this work we report an investigation of 2 inch SiC layers deposited in a new, horizontal and resistively-heated, "hot-wall" LP-CVD reactor specially designed for large flexibility.