RESUMEN
The piezoelectronic transistor (PET) has been proposed as a transduction device not subject to the voltage limits of field-effect transistors. The PET transduces voltage to stress, activating a facile insulator-metal transition, thereby achieving multigigahertz switching speeds, as predicted by modeling, at lower power than the comparable generation field effect transistor (FET). Here, the fabrication and measurement of the first physical PET devices are reported, showing both on/off switching and cycling. The results demonstrate the realization of a stress-based transduction principle, representing the early steps on a developmental pathway to PET technology with potential to contribute to the IT industry.
RESUMEN
Sophisticated microelectromechanical systems for device and sensor applications have flourished in the past decade. These devices exploit piezoelectric, capacitive, and piezoresistive effects, and coupling between them. However, high-performance piezoresistivity (as defined by on/off ratio) has primarily been observed in macroscopic single crystals. In this Letter, we show for the first time that rare-earth monochalcogenides in thin film form can modulate a current by more than 1000 times due to a pressure-induced insulator to metal transition. Furthermore, films as thin as 8 nm show a piezoresistive response. The combination of high performance and scalability make these promising candidates for nanoscale applications, such as the recently proposed piezoelectronic transistor (PET). The PET would mechanically couple a piezoelectric thin film with a piezoresistive switching layer, potentially scaling to higher speeds and lower powers than today's complementary metal-oxide-semiconductor technology.
Asunto(s)
Membranas Artificiales , Metales de Tierras Raras/química , Semiconductores , Sistemas Microelectromecánicos , Óxidos/químicaRESUMEN
We have determined the growth mode of graphene on SiC(0001) and SiC(0001¯) using ultrathin, isotopically labeled Si(13)C "marker layers" grown epitaxially on the Si(12)C surfaces. Few-layer graphene overlayers were formed via thermal decomposition at elevated temperature. For both surface terminations (Si face and C face), we find that the (13)C is located mainly in the outermost graphene layers, indicating that, during decomposition, new graphene layers form underneath existing ones.
RESUMEN
Using low-energy electron microscopy, we show that intermixing of Ge on Si(001) during growth is enhanced on stepped surfaces and is hindered on terraces where step flow does not occur. On large terraces we have identified a dramatic and unanticipated structural rearrangement that facilitates intermixing: Pairs of steps spontaneously form and migrate over the surface, leaving alloyed regions in their wake. The driving force for step formation is the entropy gain associated with the enhanced intermixing of Ge.