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Single-crystal atomic-layer-deposited (ALD) Y2O3 films 2 nm thick were epitaxially grown on molecular beam epitaxy (MBE) GaAs(001)-4 × 6 and GaAs(111)A-2 × 2 reconstructed surfaces. The in-plane epitaxy between the ALD-oxide films and GaAs was observed using in-situ reflection high-energy electron diffraction in our uniquely designed MBE/ALD multi-chamber system. More detailed studies on the crystallography of the hetero-structures were carried out using high-resolution synchrotron radiation X-ray diffraction. When deposited on GaAs(001), the Y2O3 films are of a cubic phase and have (110) as the film normal, with the orientation relationship being determined: Y2O3(110)[001][true1¯10]//GaAs(001)[110][1true1¯0]. On GaAs(111)A, the Y2O3 films are also of a cubic phase with (111) as the film normal, having the orientation relationship of Y2O3(111)[2true1¯true1¯][01true1¯]//GaAs(111)[true2¯11][0true1¯1]. The relevant orientation for the present/future integrated circuit platform is (001). The ALD-Y2O3/GaAs(001)-4 × 6 has shown excellent electrical properties. These include small frequency dispersion in the capacitance-voltage (CV) curves at accumulation of ~7% and ~14% for the respective p- and n-type samples with the measured frequencies of 1 MHz to 100 Hz. The interfacial trap density (Dit) is low of ~1012 cm−2eV−1 as extracted from measured quasi-static CVs. The frequency dispersion at accumulation and the Dit are the lowest ever achieved among all the ALD-oxides on GaAs(001).

Because the dielectric constant (K), the leakage current density (J g), and the interfacial state density (D it) are critical to high-K gate dielectrics, the layer-by-layer, in situ atomic layer bombardment (ALB) is proposed and explored to enhance these electrical properties in this study. The in situ helium/argon plasma bombardment was performed layer-by-layer in each cycle of atomic layer deposition (ALD) for preparing high-K gate dielectrics. As compared with the untreated high-K layer, the ALB treatment contributes to a significant reduction in J g by ∼3 orders of magnitude, together with an ∼11% increase of K value and a decrease of D it, of high-K gate dielectrics. The suppressed J g and the enhanced K value are ascribed to an increase of film density and a decrease of oxygen vacancies in the ZrO2 layer by the ALB treatment. The atomic annealing effect due to the ALB technique contributes to the decrease of D it. The result demonstrates that the ALD together with the ALB technique is highly effective to further enhance the dielectric properties of nanoscale thin films, which is important and applicable in a variety of fields including nanoelectronic, energy-saving, and biomedical devices.

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Tailoring of crystalline phases and dielectric properties of ZrO2 thin films are demonstrated by capping a nanoscale TiN layer prepared by plasma-enhanced atomic layer deposition. The in-plane tensile strain induced by the TiN capping layer gives rise to the dramatic paraelectric-to-antiferroelectric phase transformation in ZrO2 and the significant capacitance enhancement up to 209%. The result is attributed to the formation of the ZrO2 tetragonal phase with the out-of-plane compressive strain due to TiN capping and the presence of interfacial TiO x N y , as revealed by nanobeam electron diffraction, X-ray diffraction, and X-ray photoelectron spectroscopy. The results demonstrate that the as-deposited TiN capping layer can effectively modulate the dielectric properties of nanoscale thin films without any postannealing treatment, which is very beneficial for the back-end-of-line process integration and numerous applications including supercapacitors, microelectromechanical systems, energy conversion, and nanoelectronics.

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A novel “atomic layer substrate biasing (ALSB)” technique is proposed to improve the dielectric properties including the film density, the dielectric constant (K), the leakage current density (Jg), and the...