Resistivity reduction in Ga-doped ZnO films with a barrier layer that prevents Zn desorption

Yamada, Yasuji; Inoue, Sota; Kikuchi, Hiroe; Funaki, Shuhei

doi:10.1016/j.tsf.2018.05.001

Cited by 12 publications

(5 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…According to the previously reported annealing temperature dependence of the carrier density of GZO films [33], zinc desorption from the films to vacuum occurs at high temperatures and creates zinc vacancies that act as acceptor-like defects (electron killers) to decrease carrier density [35][36][37]. Therefore, the time-dependent decrease in the carrier density of Film 2 shown in Figure 1 is attributed to gradual zinc desorption at 500 °C.…”

Section: Effect Of Atom Diffusion On Carrier Densitymentioning

confidence: 76%

“…These oxidized films were subsequently annealed at 350 or 500 °C in vacuum at less than 0.3 Pa to extract the incorporated oxygen. These annealing temperatures were selected because the apparent modification in electrical properties was observed between 350 and 500 °C [33]. The as-deposited films were also annealed under the same vacuum annealing conditions to compare the air-annealed films.…”

Section: Methodsmentioning

confidence: 99%

“…These annealing studies focus only on the incorporation of atoms from the atmosphere, although desorption of Zn and O from the ZnO lattice is observed in thermal desorption spectroscopy at high temperatures [26][27][28][29][30][31][32]. A few studies describe property changes that are caused by zinc desorption, by which the carrier density decreases drastically at high temperatures in a vacuum [32,33]. To understand and control the properties of doped ZnO films, the revelation of the absorption and desorption processes of atoms at high temperatures is important.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Variation in electrical and structural properties of Ga-doped ZnO films caused by oxygen out-diffusion

Sugiura

Yamada

Funaki

2021

Trans. Mat. Res. Soc. Japan

Self Cite

View full text Add to dashboard Cite

The effect of oxidation and the subsequent vacuum annealing on the electrical and structural properties of Ga-doped ZnO (GZO) films prepared by sputtering was investigated with respect to annealing temperature and time. The annealing of the GZO films in air caused severe reduction in carrier density, but subsequent vacuum annealing partially recovered the carrier density. This change in carrier density indicates that oxygen atoms are easily incorporated into and released from the GZO film. As the vacuum annealing time increased at an annealing temperature of 500 °C, the recovery of the carrier density peaked and then decreased. This annealing-time dependence is attributed to the co-desorption of oxygen and zinc and indicates that oxygen diffusion is faster than that of zinc in Ga-doped ZnO films. Air annealing reduces the carrier density and mobility of films. However, subsequent vacuum annealing results in the recovery of the carrier density and the enhancement of mobility, depending on the annealing temperature. The enhancement of mobility suggests that an adequate arrangement of incorporated oxygen atoms at the grain boundary reduces carrier scattering in GZO films.

show abstract

Section: Effect Of Atom Diffusion On Carrier Densitymentioning

confidence: 76%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Variation in electrical and structural properties of Ga-doped ZnO films caused by oxygen out-diffusion

Sugiura

Yamada

Funaki

2021

Trans. Mat. Res. Soc. Japan

Self Cite

View full text Add to dashboard Cite

show abstract

“…ZnO has attracted much attention as a remarkable multi-functional material with a wide range of existing and emerging applications, such as varistors, , transparent conducting electrodes, − surface-acoustic-wave (SAW) devices, , gas sensors, , X-ray imaging systems, and thin-film transistors. − Several studies have reported that high-quality single-crystalline ZnO films grow on lattice-matched epitaxial substrates, such as bulk ZnO substrates and ScAlMgO 4 substrates. − However, these substrates are expensive and thus make ZnO films of potentially limited use for large-scale devices. Cost-effective c -plane sapphire is a promising candidate as a substrate for the epitaxial growth of ZnO films because of its cost efficiency if single-crystalline ZnO films grew by overcoming the obstacle of the large lattice mismatch of 18%, which causes a number of crystal defects including 30°-rotated domains and threshold dislocations. , …”

Section: Introductionmentioning

confidence: 99%

Growth of Single-Crystalline ZnO Films on 18%-Lattice-Mismatched Sapphire Substrates Using Buffer Layers with Three-Dimensional Islands

Nakamura

Yamashita

Kamataki

et al. 2022

Crystal Growth & Design

View full text Add to dashboard Cite

Heteroepitaxial growth of single-crystalline zinc oxide (ZnO) films on a c-plane sapphire substrate is an important technology for electronics and optoelectronic devices. Recently, the inverted Stranski–Krastanov (SK) mode has been demonstrated, and it has realized the heteroepitaxial growth of ZnO films on a sapphire substrate by sputtering. In this mode, a 10 nm-thick buffer layer consisting of three-dimensional islands (3D buffer layers) initially forms and relaxes the strain, and then, a two-dimensional ZnO film (2D layer) grows involving small strain. To clarify the correlation between the structural properties of the 3D buffer layers and the 2D layer, we introduce a figure of merit (FOM) of ZnO films: the reciprocal of the product of the full width at half-maximum (FWHM) of the (002) and (101) planes of X-ray rocking curves (XRCs) and root-mean-square (RMS) roughness. We find that the FOM of the 2D layers correlates with the RMS roughness, the in-plane orientation, and the lateral correlation length ξ of the surfaces of the buffer layers. We observe a surprisingly high correlation coefficient of 0.97. Our results imply that on the buffer layers with larger ξ, adatoms more easily reach the thermodynamically favored lattice positions. Thus, high-quality single-crystalline ZnO films, where the (002) plane XRC-FWHM and the RMS roughness are 0.05° and 1.5 nm, respectively, are grown on the buffer layers with a large ξ of 13.7 nm. This finding provides a useful tool for understanding the mechanism of the inverted SK mode.

show abstract

“…Moreover, it has been reported that Zn desorption from Gadoped ZnO (GZO) films can occur when annealed at 500 °C in a vacuum, leading to a reduction in carrier concentration. [16][17][18][19] This carrier reduction can also be explained by oxygen enrichment relative to Zn in the GZO lattice, with a possible defect equation as follows:…”

mentioning

confidence: 99%

Improved sputtering method to deposit high conducting doped ZnO films without substrate heating

Yamada,

Funaki

2023

Appl. Phys. Express

Self Cite

View full text Add to dashboard Cite

Magnetron sputtering deposition with Zn supply was utilized to deposit Ga-doped ZnO (GZO) films to minimize acceptor-like crystalline defects. This deposition technique significantly increased the carrier concentration of GZO films. In addition, the impact of the partial oxygen pressure in the deposition atmosphere on carrier concentration was remarkably reduced. As a result, the resistivity of the films decreased to as low as 4×10-4 Ωcm without the need for intentional substrate heating. Consequently, the deposition with Zn supply shows great potential for producing ZnO-based transparent conducting films with practically low resistivity on polymer substrates that have lower heat tolerance.

show abstract

Resistivity reduction in Ga-doped ZnO films with a barrier layer that prevents Zn desorption

Cited by 12 publications

References 36 publications

Variation in electrical and structural properties of Ga-doped ZnO films caused by oxygen out-diffusion

Variation in electrical and structural properties of Ga-doped ZnO films caused by oxygen out-diffusion

Growth of Single-Crystalline ZnO Films on 18%-Lattice-Mismatched Sapphire Substrates Using Buffer Layers with Three-Dimensional Islands

Improved sputtering method to deposit high conducting doped ZnO films without substrate heating

Contact Info

Product

Resources

About