Epitaxial growth of insulator oxides on semiconductors is a key topic in electronics and spintronics, and Ge, due to its high electronic and hole mobilities, represents a promising candidate for the next generation high performance Complementary Metal-Oxide-Semiconductor Field-Effect Transistor (CMOSFET). Moreover, Germanium is expected to play a relevant role in Spintronics, due to the large spin-orbit splitting allowing spin manipulation via external fields, thus envisaging the development of “spin-devices” (such as spin-transistors and spin-valves) where the charge is substituted by the spin as information carrier.
Our research in this field is focused on Fe/MgO/Ge(001) heterostructures, grown by Molecular Beam Epitaxy and magnetron sputtering and characterized in-situ by electron spectroscopies and diffraction techniques [bibcite key=Cantoni2011a]. The spin transport properties are measured by optical and magneto-transport techniques on protoypical devices fabricated by (optical and electron-beam lithography), such as spin-photodiodes and lateral transport devices.
In this frame, we recently realized and reported in Advanced Materials [bibcite key=Rinaldi2012] the first demonstration of room-temperature operation of Ge-based spin-photodiodes for integrated electrical detection of the light polarization, finally opening the way towards a Ge-based spin-opto-electronics on a wide spectral range. [bibcite key=Rinaldi2014a]
A second research line on semiconductor spintronics focuses on the narrow gap ferroelectric semiconductor GeTe, for which the opportunity for the electric control of the Giant Rashba Effect has been predicted. In-situ and synchrotron-based (Elettra) characterization of GeTe thin films are in progress, in order to evaluate the opportunity of realizing a spin-transistor with GeTe employed as gate and active channel. [bibcite key=Rinaldi2014b]
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