Epitaxial growth of Sc2O3 films on GaN

Abstract

Thin films of scandium oxide were epitaxially deposited on GaN via molecular beam epitaxy using elemental Sc and an oxygen plasma. After growth, the Sc2O3 films were annealed at a temperature of 800°C for 5min in the growth chamber. The structural quality of Sc2O3 films, before and after annealing, was characterized using high-resolution x-ray diffraction, atomic force microscopy (AFM), and high-resolution transmission electron microscopy (HRTEM). AFM of the films revealed smooth surfaces with 0.38nm root mean square roughness and show evidence of step-flow growth. The rocking curve and reflectivity scans of the films reveal that the Sc2O3∕GaN interface is abrupt and that it remains so after annealing. Pole figure and grazing incidence θ-2θ measurements show that the films are very textured along the c axis of the GaN substrate. HRTEM produced lattice images of the Sc2O3∕GaN interface illustrating the single crystal growth of the Sc2O3 films on the GaN.

Role of Gate Oxide in AlGaN/GaN High-Electron-Mobility Transistor pH Sensors

“…The Sc 2 O 3 was deposited by radiofrequency (RF) plasma-activated molecular beam epitaxy (MBE) at 100°C using elemental Sc evaporated from a standard effusion all at 1130°C and O 2 derived from an Oxford RF plasma source. [22][23][24] For comparison, we also fabricated devices with just the native oxide present in the gate region and also with a UV-ozone-induced oxide. The latter was produced by exposing the sample to UVozone at room temperature for 5 min.…”

Textured Magnesium Titanate as Gate Oxide for GaN-Based Metal-Oxide-Semiconductor Capacitor

“…In particular, ceramic lattice that is coherent to the c-plane GaN may reduce the numbers of interface defects, resulting in an efficient surface inversion layer in the MOS device. 15,16 This work demonstrates the use of high-permittivity (e r ) ilmenite ceramic as a gate oxide in GaN-based MOS. Ilmenite MgTiO 3 thin film with a (003)-preferred orientation was obtained on (0001) GaN by sputtering in an atmosphere of oxygen.…”

“…Metal-oxide-semiconductor FETs (MOS-FETs) and MOS-HFETs with a low leakage current have reportedly been formed by introducing a thin gate oxide such as AlN, Ga 2 O 3 , SiO 2 , Si 3 N 4 , Al 2 O 3 , HfO 2 , MgO, or Ta 2 O 5 . 15,16 This work demonstrates the use of high-permittivity (e r ) ilmenite ceramic as a gate oxide in GaN-based MOS. [5][6][7][8][9][10][11][12][13][14] However, for a long time, only a few metal oxides have been used as gate oxides.…”

Confocal single molecule fluorescence spectroscopy in ultrahigh vacuum

“…5͑b͒ onto a 45-Å-thin, atomically flat layer of Sc 2 O 3 ͑111͒ grown heteroepitaxially on GaN ͑0001͒. 23 Most spots correspond to single C 4 -PTCDI molecules, although in each image a bright feature originating from a cluster of multiple molecules inside the laser excitation and detection area can also be seen. Characteristic fluorescence intermittency and transitions to long-lived dark states are observed in both images.…”