Optical properties and bandgap evolution of ALD HfSiOx films

Yang, Wen; Fronk, Michael; Geng, Yanquan; Chen, Lin; Sun, Qizhen; Gordan, Ovidiu D.; Zhou, Peng; Zahn, Dietrich R. T.; Zhang, David Wei

doi:10.1186/s11671-014-0724-z

Cited by 14 publications

(14 citation statements)

References 29 publications

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“…In figures 1(a) and (b), the modelled curve and the experimental data show some discrepancy near the band gap (∼300 nm) energy of HfO 2 . This situation is encountered already in the literature for HfO 2 and HfSiO x film [7,19]. From the figure 1, it can be clearly seen that a perfect agreement between the experimental data and the modeled curve has been achieved in the high wavelength range for the HfO 2 films.…”

Section: Resultssupporting

confidence: 70%

Comparision of in situ spectroscopic ellipsometer and ex situ x-ray photoelectron spectroscopy depth profiling analysis of HfO₂/Hf/Si multilayer structure

Cantaş

Özyüzer

Aygün

2018

Mater. Res. Express

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A HfO 2 film was grown by RF magnetron sputtering technique on a Si substrate Using in situ Spectroscopic Ellipsometry (SE), the film thickness and refractive index were examined as a function of deposition time. Ex situ x-ray Photoelectron Spectroscopy (XPS) was used in depth profile mode to determine the phase evolution of HfO 2 /Hf/Si multilayer structure after the growth process. The chemical composition and the crystal structure of the film were investigated by Fourier Transform Infrared (FTIR) spectroscopic measurements and x-ray Diffraction in Grazing Incidence (GI-XRD) mode, respectively. The results showed that the film was grown in the form of HfO 2 film. According to SE analysis, reactive deposition of HfO 2 directly on Hf/Si results to SiO 2 interface of about 2 nm. The final HfO 2 films thickness is 5.4 nm. After a certain period of time, the XPS depth profile revealed that the film was in the form of Hf-rich Hf silicate with SiO 2 interfacial layer. In reference to XPS quantification analysis from top to bottom of film, the atomic concentration of Hf element reduces from 19.35% to 7.13%, whereas Si concentration increases from 22.99% to 74.89%. The phase change of HfO 2 film with time is discussed in details. RECEIVED

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Section: Resultssupporting

confidence: 70%

Comparision of in situ spectroscopic ellipsometer and ex situ x-ray photoelectron spectroscopy depth profiling analysis of HfO₂/Hf/Si multilayer structure

Cantaş

Özyüzer

Aygün

2018

Mater. Res. Express

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“…Taking the total concentration of contaminants and plotting it against DEv (measured -predicted), a clear pattern is observed and shown in Figure 30. The literature shows that energy band alignment variations of sometimes more than 1 eV depending on interface preparation can be obtained, [212][213][214][215][239][240][241][242] due to the presence of high defect concentrations in the materials and on a cation effect that will increase the VBM of that material. 117 The oxides of Ti, Cr, Cu, and Fe have much lower bandgaps ($1.5-3.4 eV) and thus contribute to a lowering of the average gap of the films.…”

Section: Methodsmentioning

confidence: 99%

Energy band offsets of dielectrics on InGaZnO4

Hays

Gila

Pearton

et al. 2017

Applied Physics Reviews

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Thin-film transistors (TFTs) with channels made of hydrogenated amorphous silicon (a-Si:H) and polycrystalline silicon (poly-Si) are used extensively in the display industry. Amorphous silicon continues to dominate large-format display technology, but a-Si:H has a low electron mobility, l $ 1 cm 2 /V s. Transparent, conducting metal-oxide materials such as Indium-Gallium-Zinc Oxide (IGZO) have demonstrated electron mobilities of 10-50 cm 2 /V s and are candidates to replace a-Si:H for TFT backplane technologies. The device performance depends strongly on the type of band alignment of the gate dielectric with the semiconductor channel material and on the band offsets. The factors that determine the conduction and valence band offsets for a given material system are not well understood. Predictions based on various models have historically been unreliable and band offset values must be determined experimentally. This paper provides experimental band offset values for a number of gate dielectrics on IGZO for next generation TFTs. The relationship between band offset and interface quality, as demonstrated experimentally and by previously reported results, is also explained. The literature shows significant variations in reported band offsets and the reasons for these differences are evaluated. The biggest contributor to conduction band offsets is the variation in the bandgap of the dielectrics due to differences in measurement protocols and stoichiometry resulting from different deposition methods, chemistry, and contamination. We have investigated the influence of valence band offset values of strain, defects/vacancies, stoichiometry, chemical bonding, and contamination on IGZO/dielectric heterojunctions. These measurements provide data needed to further develop a predictive theory of band offsets. Published by AIP Publishing.

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“…In this research, the "n" values we measured for HfO 2 and HfSiOx films annealed at 500 o C were 1.748 and 1.872, respectively. Since the Si-O bonds were less polar than the corresponding Hf-O bands 19 , the addition of Si would lead to a decrease of the film polarization, and then lowering the refractive index of HfSiOx films 40 . Since the Si-O bonds were less polar than the corresponding Hf-O bands 19 , the addition of Si would lead to a decrease of the film polarization, and then lowering the refractive index of HfSiOx films 40 .…”

Section: Resultsmentioning

confidence: 99%

“…Meanwhile, the energy bandgap of HfO 2 was enlarged and the breakdown voltage was increased owing to the silicon doping. Simultaneously, few groups 17 However, to date, most of HfSiOx dielectrics were fabricated through expensive vacuum-based deposition process such as atomic layer deposition 17,21,22 , sputtering 13,20 and electron bean evaporation 23 , which suffered from high manufacturing costs and limitation to large area deposition capabilities. Thus, it is believed to be a good dielectric candidate in direct contact with Si and can meet requirements for high resolution and low consumption AMFPD display technology 19 .…”

Section: Introductionmentioning

confidence: 99%

Solution processable amorphous hafnium silicate dielectrics and their application in oxide thin film transistors

Gao

Lü

et al. 2015

J. Mater. Chem. C

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A novel solution-processed amorphous high-k dielectric for thin film transistors (TFTs) has been systemically studied with the objective of achieving high performance and reducing costs for the next generation displays. In this research, the amorphous hafnium silicon multiple oxide (HfSiOx) was fabricated by the simple spin-coating method. Here, we have demonstrated that the incorporation of a silicon oxide has significant effects on the properties of HfO2. The HfSiOx dielectrics have no obvious crystallization peaks even the annealing temperature reach up to 800 o C while the HfO2 films were crystallized at 400 o C. The HfSiOx films have an energy band gap of 6.05 eV, which was wider than HfO2 films (5.69 eV), the breakdown voltage was increased from 2.4 MV/cm (HfO2) to 2.9 MV/cm (HfSiOx) and the leakage current was decreased from 4.4×10 -7 A/cm 2 to 3.7×10 -7 A/cm 2 at an electric field of 2 MV/cm. To achieve optimized device performance, the influence of annealing temperature on the characteristics (including the surface and interface, the chemical and structural evolution) of the solution processed HfSiOx dielectrics was emphasized in this research. To demonstrate the HfSiOx application on oxide TFTs, we fabricated HfInZnO (HIZO) and ZnSnO (ZTO) TFTs with HfSiOx dielectrics, and both of them showed low off-state current indicating the HfSiOx is an attractive candidate used in TFTs. The ZTO TFTs with amorphous HfSiOx dielectrics were operated well under a gate voltage of -0.53 V, exhibiting a high saturation mobility of 153 cm 2 /V·s, a small subthreshold swing of 0.17 V/dec, a large on-off current ratio 3.4×10 7 .

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Optical properties and bandgap evolution of ALD HfSiOx films

Cited by 14 publications

References 29 publications

Comparision of in situ spectroscopic ellipsometer and ex situ x-ray photoelectron spectroscopy depth profiling analysis of HfO₂/Hf/Si multilayer structure

Comparision of in situ spectroscopic ellipsometer and ex situ x-ray photoelectron spectroscopy depth profiling analysis of HfO₂/Hf/Si multilayer structure

Energy band offsets of dielectrics on InGaZnO4

Solution processable amorphous hafnium silicate dielectrics and their application in oxide thin film transistors

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Optical properties and bandgap evolution of ALD HfSiOx films

Cited by 14 publications

References 29 publications

Comparision of in situ spectroscopic ellipsometer and ex situ x-ray photoelectron spectroscopy depth profiling analysis of HfO2/Hf/Si multilayer structure

Comparision of in situ spectroscopic ellipsometer and ex situ x-ray photoelectron spectroscopy depth profiling analysis of HfO2/Hf/Si multilayer structure

Energy band offsets of dielectrics on InGaZnO4

Solution processable amorphous hafnium silicate dielectrics and their application in oxide thin film transistors

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Comparision of in situ spectroscopic ellipsometer and ex situ x-ray photoelectron spectroscopy depth profiling analysis of HfO₂/Hf/Si multilayer structure

Comparision of in situ spectroscopic ellipsometer and ex situ x-ray photoelectron spectroscopy depth profiling analysis of HfO₂/Hf/Si multilayer structure