Tae Joo Park

Abstract A high‐performance, transparent, and extremely thin (<15 nm) hydrogen (H 2 ) gas sensor is developed using 2D electron gas (2DEG) at the interface of an Al 2 O 3 /TiO 2 thin film heterostructure grown by atomic layer deposition (ALD), without using an epitaxial layer or a single crystalline substrate. Palladium nanoparticles (≈2 nm in thickness) are used on the surface of the Al 2 O 3 /TiO 2 thin film heterostructure to detect H 2 . This extremely thin gas sensor can be fabricated on

The gate leakage current density (Jg) of ultrathin (∼3 nm) Al-doped HfO2 (Al:HfO2) films with an Al concentration of ∼11% was lower than that of the control HfO2 film by 2 orders of magnitude at an equivalent oxide thickness of ∼1 nm. The permittivity of the Al:HfO2 film was similar to that of the control HfO2 film. Al doping of HfO2 films reduced the concentration of the oxygen vacancies and carbon in the film, which act as electrical defects (traps). It also increased the band gap of the film,

We report the field-effect transistors using quasi-two-dimensional electron gas generated at an ultrathin (∼10 nm) Al₂O₃/TiO₂ heterostructure interface grown via atomic layer deposition (ALD) on a SiO₂/Si substrate without using a single crystal substrate. The 2DEG at the Al₂O₃/TiO₂ interface originates from oxygen vacancies generated at the surface of the TiO₂ bottom layer during ALD of the Al₂O<s

A two-dimensional electron gas (2DEG) was formed at the interface of an ultrathin Al2O3/TiO2 heterostructure that was fabricated using atomic layer deposition (ALD) at a low temperature (<300 °C) on a thermally oxidized SiO2/Si substrate. A high electron density (∼1014 cm–2) and mobility (∼4 cm2 V–1 s–1) were achieved, which are comparable to those of the epitaxial LaAlO3/SrTiO3 heterostructure. An in situ resistance measurement directly demonstrated that the resistance of the heterostructure in

Atomic-layer deposition (ALD) is a thin-film growth technology that allows for conformal growth of thin films with atomic-level control over their thickness. Although ALD is successful in the semiconductor manufacturing industry, its feasibility for nanoparticle coating has been less explored. Herein, the ALD coating of TiO2 layers on ZnO nanoparticles by employing a specialized rotary reactor is demonstrated. The photocatalytic activity and photostability of ZnO nanoparticles coated with TiO2 l

We demonstrate the conformal coating of an ultrathin Al2 O3 layer on TiO2 nanoparticles through atomic layer deposition by using a specifically designed rotary reactor to eliminate the phototoxicity of the particles for cosmetic use. The ALD reactor is modified to improve the coating efficiency as well as the agitation of the particles for conformal coating. Elemental and microstructural analyses show that ultrathin Al2 O3 layers are conformally deposited on the TiO2 nanoparticles with a control

A new model for the growth behavior of saturated HfO2 films by atomic layer deposition (ALD) was suggested. The well-known ALD saturation of the growth rate with increasing precursor input was observed, but the full saturation required an extremely long feeding time. After the rapid increase in growth rate with increasing precursor feeding time, a pseudo-saturation region was observed where full saturation was hindered by the “screening effect” of the physisorbed precursor molecules or byproduct