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TEM images of the interface in samples prepared by thermal ALD of from and precursors on HCl-etched GaAs (a) and from and on the pristine GaAs surface (b). The arrows indicate the thicknesses of the of the IL between and GaAs.
yield as a function of photon energy in samples with plasma-assisted (●) and thermal ALD oxides (◯) measured under positive bias (a) of 0.5, 0.7, 1.0, 1.5, 2.0, 2.5, or 3.0 V, or negative bias (b) of , , or applied to the Au electrode. The vertical lines indicate energies of optical singularities in GaAs; vertical arrows mark thresholds of intrinsic PC in and . The insets show schematics of electron transitions.
yield as a function of photon energy measured on samples with layers deposited from and without (●) and with pre-ALD HCl surface clean (◯) measured under positive (a) 2 V bias and negative bias (b) of , , or on the Au electrode. The spectra (◻) taken at and biases on samples with 15 nm thick grown at from and are shown for comparison. The inset illustrates determination of the hole IPE threshold using plots. The vertical lines indicate energies of optical singularities in GaAs, while vertical arrows show the threshold of intrinsic PC in .
Determination of the electron IPE spectral thresholds from plots in samples with (a) and (b) insulators measured under different positive voltages applied to the Au top electrode. The inset in panel (a) shows the Schottky plot of the thresholds of electron IPE from the GaAs VB into the CB of (◯, ◻), (△), and the IL (▽). Vertical arrows mark the observed threshold energies; lines guide the eye.
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