Atomic layer deposition of titanium oxide thin films using a titanium precursor with a linked amido-cyclopentadienyl ligand

Abstract

We studied the atomic layer deposition (ALD) of titanium oxide (TiO2) using a newly-developed heteroleptic titanium precursor with a linked ligand. The titanium precursor, [2-(N-methylamino) 1-methyl ethyl cyclopentadienyl] bis(dimethylamino) titanium...

Elaborating the interplay between the detecting unit and emitting unit in infrared quantum dot up-conversion photodetectors

“…Colloidal quantum dots (CQDs) are promising nano-semiconductor materials, which are characterized by size-tunable bandgap and solution processibility. [8][9][10] Among them, lead sulfide (PbS) CQDs exhibit excellent capabilities of photon-electron conversion, and the absorption wavelength can be extended to the short-wave infrared region (1-2.7 μm). The incident photon-to-electron conversion efficiency (IPCE) of the conventional photodiode (PD) based on PbS CQDs has reached 80%, [11][12][13] while the external quantum efficiency (EQE) of the visible quantum-dot light emitting diodes (QLEDs) has also exceeded 25%.…”

Selective etching mechanism of silicon oxide against silicon by hydrogen fluoride: a density functional theory study

“…The exothermicity can be described by the formation of Si-F (7.15 eV) and O-H (5.20 eV) bonds in P1 despite the dissociation of Si-O (6.15 eV) and H-F (6.02 eV) bonds. The bond dissociation energies (BDEs) were calculated using the method in the literature, 10,43,44 and the details were summarized in Fig. S1 and S2 of ESI.…”

“…Fig. 6 shows the energy diagrams and the changes in the atomistic structure of the fourth step in eqn (10). R4 showed the physisorption of HF with an energy of À0.37 eV, which is more favorable than in the second and third steps due to the two hydrogen bonds.…”

“…Density functional theory (DFT) calculation is an excellent method for understanding the reactions of a chemical species with a solid surface. [7][8][9][10][11][12] The etching of SiO 2 by four HF molecules or HF/H 2 O mixture has been investigated by DFT using a small cluster model of Si 3 O 4 H 8 , which is extracted from Si 7 O 10 H 16 . 13,14 Hoshino et al calculated the activation energies for the etching of SiO 2 by HF, and the highest activation energy was 1.33 eV, which is relatively high for near-room temperature processes.…”

Role of Cyclopentadienyl Ligands of Group 4 Precursors toward High-Temperature Atomic Layer Deposition

“…These precursors, however, sometimes have drawbacks such as halide contamination and low stabilities in the case of the halide and alkoxides, respectively. Consequently, heteroleptic precursors including more than one type of ligands such as cyclopentadienyl (Cp)-alkoxides and Cp-alkylamides are developed, to enhance the thermal stability of precursors of the ALD high-k oxides. − When ozone is used as the oxygen source, ALD using zirconium and hafnium Cp-alkylamide precursors shows high growth per cycle (GPC), ranging from 0.8 to 0.9 Å per cycle, and the deposited films mostly possessed low levels of nitrogen and carbon contamination. Especially, ZrO 2 and HfO 2 films deposited using CpZr­(N­(Me 2 ) 3 and CpHf­(N­(Me 2 ) 3 precursors (Me = CH 3 ) and ozone have shown improved film density and electrical performance, possibly due to the deposition temperatures being as high as 350 °C.…”