(Color online) (a) Schematic of the HEMT structures studied under APT. (b) TEM image of a typical AlInN/GaN specimen obtained using FIB, showing a diameter of 100 nm and a shank angle of 8°. (c) APT reconstruction of Al0.83In0.17N/GaN HEMT structure.
(Color online) APT mass-to-charge spectra comparison of voltage mode (top, black) and laser mode (bottom, red). The inset shows a closer look of the spectra in the region of Ga++ (peaks at m/c 34.5 and 35.5).
(Color online) Mass-to-charge spectrum near m/c 14 showing the theoretically possible positions of peaks associated with nitrogen. The absence of a peak at 14.5 suggests that the peaks experimentally observed correspond to N+ and there is no measurable contribution from N2 ++.
(Color online) Gallium and nitrogen concentrations determined from APT as a function of laser pulse energy.
Typical mass-to-charge spectra for (a) AlInN/GaN and (b) AlGaN/GaN HEMT structures.
(Color online) Isosurface reconstruction for AlGaN/GaN (a) before and (b) after 60Co irradiation exposure at 6 Mrad(Si). The top blue isosurfaces correspond to Al (at ∼9%) while the bottom gold isosurfaces correspond to Ga (∼91%). The Al surface RMS roughness increased from 1.5 to 1.8 nm, while the Ga roughness increased from 0.94 to 1.5 nm after irradiation.
(Color online) Isosurface reconstruction for AlInN/GaN (a) before and (b) after 60Co irradiation exposure at 6 Mrad(Si). The top blue isosurfaces correspond to Al (at ∼31%), the center violet isosurfaces correspond to In (∼2%), and the bottom gold isosurfaces correspond to Ga (∼67%). The Al surface RMS roughness increased from 0.23 to 1.2 nm, the In roughness increased from 1.2 to 1.4 nm, and the Ga roughness increased from 0.23 to 0.80 nm.
(Color online) Proximity histogram, before (solid blue line) and after irradiation (dashed red line), for Al and Ga centered at the interface shown in Fig. 7 .
Room temperature Hall measurements for AlInN/GaN and AlGaN/GaN structures before and after 60Co irradiation.
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