Ballistic electron emission microscopy is utilized to investigate the hot-electron scattering properties of Cu through Cu/Si(001) Schottky diodes. A Schottky barrier height of 0.64±0.02 eV and a hot-electron attenuation length of 33.4±2.9 nm are measured at a tip bias of 1.0 eV and a temperature of 80 K. The dependence of the attenuation length with tip bias is fit to a Fermi liquid model that allows extraction of the inelastic and elastic scattering components. This modeling indicates that elastic scattering due to defects, grain boundaries, and interfaces is the dominant scattering mechanism in this energy range.
Articles you may be interested inSchottky barrier height measurements of Cu/Si(001), Ag/Si(001), and Au/Si(001) interfaces utilizing ballistic electron emission microscopy and ballistic hole emission microscopy AIP Advances 3, 112110 (2013); 10.1063/1.4831756 Hot-electron transport studies of the Ag/Si(001) interface using ballistic electron emission microscopy J. Vac. Sci. Technol. A 28, 643 (2010); 10.1116/1.3397795 Ambipolar ballistic electron emission microscopy studies of gate-field modified Schottky barriers Appl. Phys. Lett. 96, 242106 (2010); 10.1063/1.3453866Ion-bombardment effects on PtSi /n -Si Schottky contacts studied by ballistic electron emission microscopy
Ballistic electron emission microscopy has been utilized to investigate the hot-electron transport properties of the Ag/Si(001) Schottky diode utilizing metal films deposited both in situ and ex situ. The Schottky barrier heights are measured to be 0.57±0.02 and 0.59±0.02 eV for the ex situ and in situ depositions, respectively. The metal overlayers demonstrate typical Volmer–Weber growth when deposited on the Si(001) semiconducting substrate, as seen in the scanning tunneling microscopy images. An enhancement in hot-electron transmission is measured for the in situ deposited metal films when compared to the ex situ films.
Ballistic electron emission microscopy (BEEM) was performed to obtain nanoscale current versus bias characteristics of non-epitaxial Au on p-type GaAs in order to accurately measure the local Schottky barrier height. Hole injection BEEM data was averaged from thousands of spectra for various metal film thicknesses and then used to determine the attenuation length of the energetic charge carriers as a function of tip bias. We report the marked increase in attenuation length at biases near the Schottky barrier, providing evidence for the existence of coherent BEEM currents in Schottky diodes. These results provide additional evidence against the randomization of a charge carrier's momentum at the metal-semiconductor interface. thibado@uark.edu -2-
Aluminum oxide films were grown on Si under ultrahigh vacuum conditions for use as tunnel barriers in spin injection studies. X-ray photoelectron spectroscopy was performed to characterize the film stoichiometry. It was observed that all the aluminum was bonded to the oxygen for the films grown in 1 nm steps. Whereas the 2 nm sample grown in one 2 nm step left a partially unoxidized aluminum film. Current-voltage measurements were performed and fitted to a tunnel model. The resistance area products fall within the range needed for spin injection and nonlocal readout.
Electrical scanning probe microscopes, such as the scanning capacitance microscope (SCM) for two dimensional dopant profiling, scanning Kelvin force microscope (SKFM) for surface potential measurements, and tunneling atomic force microscope (TUNA) for dielectric integrity measurements, are important tools for characterizing CMOS and nanoelectronic devices. A significant limitation of all these techniques is the terminal tip radius and the cone angle of the shank of the tip, which contribute substantial stray capacitance to the signal resulting in signal averaging over an area much wider than the terminal tip. To overcome this limitation, we have used conventional SPM tips terminated with a welded carbon nanotube (CNT). We have examined ultra-shallow junctions, high-κ gate stacks, low-κ intermetal dielectrics, and FinFET devices in cross-section with SCM and SKFM, using both conventional and CNT-terminated tips. We have also measured the electrical properties of the CNT-terminated tips. Spatial resolution improved substantially with the CNT-terminated tips compared to the conventional tips, but the CNT tips can introduce additional artifacts. We will present detailed comparisons of the two types of tips used for various SPM-based electrical characterization measurements that are useful for nanoelectronics. FIGURE 1. SCM images of 65 nm FINS measured with conventional (left) and CNT-terminated (right) tips.
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