Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 50: III-V Semiconductors II (mainly Arsenides)
HL 50.1: Vortrag
Mittwoch, 28. März 2012, 09:30–09:45, EW 203
Free-standing rolled-up metal oxide field-effect-transistor — •Daniel Grimm1, Carlos C. B. Bufon1, Dominic J. Thurmer1, Christoph Deneke1,2, Franziska Schäffel1, Paola Atkinson1,3, and Oliver G. Schmidt1 — 1IFW Dresden, Germany — 2LNLS, Campinas, Brazil — 3Institut des nanosciences de Paris, France
In this work we demonstrate for the first time a three-dimensional free-standing metal oxide field-effect-transistor based on strained hybrid nanomembranes. The fabrication process combines conventional device patterning with selective etching to form the three-dimensional rolled-up transistor (RUFET).
Firstly, Ohmic contacts, gate electrodes and Al2O3 dielectrics are defined on the surface of single-crystalline semiconducting multilayers grown on top of a sacrificial layer. Upon selective etching of the sacrificial layer, the complete planar transistor curls up so that the nanomembrane based channel bonds back onto the gate electrode resulting in a rolled-up double-gate device. This rolled-up technique yields a substantial reduction of the free-standing device footprint, decreasing further the body effect.
The employed GaAs layers show a variety of surface states, which pin the Fermi-level forming rather deep depletion regions. By Poisson’s equation calculations we engineer the thickness and doping level close to the complete depletion regime. The RUFET is then driven in the depletion mode regime and showed typical transfer characteristics as well as gate-voltage swings around 200 mV/decade with on-off ratios of several orders of magnitudes.