Ferroelectric thin film field-effect transistors based on heterostructures
(Color online) Principle layout of ZnO/BTO MISFET transistors.
(Color online) XRD scan of a STO:Nb (100)/BTO/ZnO/Au heterostructure. The following out-of-plane orientations of the thin film were detected: BTO (001), ZnO(002), and Au(111). No other orientation was revealed, indicating epitaxial growth.
(Color online) XRD wide angle scans of asymmetric peaks of a STO:Nb (100)/BTO/ZnO/Au heterostructure. The fourfold symmetry of the BTO (103) peaks is in perfect alignment with the substrate STO (310) peaks. The 12 ZnO (104) peaks indicate hexagonal symmetry with 30° rotational domains. The ZnO (104) peaks have been scaled up by a factor of 10 for visibility.
(Color online) characteristic of a reference MIS diode sample with 2 mm diameter Ohmic contacts for different integration times . Points of current maxima have been demarked by vertical lines, voltage points for the determination of and are shown (refer to text).
(Color online) characteristics of two individual transistors (leakage current characteristics) on the same sample. A charging behavior is obvious in both curves, which is attributed to the ferroelectric switching of the BTO.
(Color online) Output characteristics of a ZnO/BTO MISFET at different gate voltages. The dashed line is a guide to the eye, underlining the quadratic behavior of the position of the pinch off points.
(Color online) Transfer characteristics and calculated channel mobility of a ZnO/BTO MISFET at a fixed source drain voltage of .
(Color online) (a) Transfer characteristics of a ZnO/BTO MISFET after applying forward and backward pulses, respectively. (b) Ratio of the current in the permanent “on” and the permanent “off” state.
FWHM of HR-XRD rocking curves, of wide-angle XRD -scans, and of wide-angle XRD peaks of a ZnO/BTO heterostructure grown on a single crystalline STO:Nb substrate. The last column gives the out-of-plane lattice constant determined from the selected symmetrical reflexes.
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