Room-Temperature-Synthesized High-Mobility Transparent Amorphous CdO–Ga<sub>2</sub>O<sub>3</sub> Alloys with Widely Tunable Electronic Bands

Liu, Chao Ping; Ho, Chun Yuen; Reis, Roberto dos; Foo, Yishu; Guo, Peng; Zapien, Juan Antonio; Walukiewicz, W.; Yu, Kin Man

doi:10.1021/acsami.7b18254

Cited by 29 publications

(11 citation statements)

References 57 publications

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“…Compared to earlier works, the composition of the materials became more complex, and mainly ternary oxides were reported on. 37–63 The extreme super high mobilities reported in previous studies, i.e. above 100 cm 2 V −1 s −1 , were however not seen anymore, except for some outliers.…”

Section: Introductionmentioning

confidence: 61%

Complex amorphous oxides: property prediction from high throughput DFT and AI for new material search

et al. 2022

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Section: Introductionmentioning

confidence: 61%

Complex amorphous oxides: property prediction from high throughput DFT and AI for new material search

et al. 2022

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“…Alloying of undoped CdO with large band gap materials has been explored to tune the band gap and improve its transmittance across larger spectral ranges. Several wider-band-gap oxide materials, such as Ga 2 O 3 , In 2 O 3 , ZnO, , MgO, and NiO, , have been applied toward this goal of improving the short-wavelength transparency in CdO-based systems for applications as transparent conductive oxides. Among these oxides, p-type NiO has a type-III band offset with CdO and the NiO–CdO alloy system offers an opportunity not only to widen the band gap in CdO but also to control the conductivity type .…”

Section: Introductionmentioning

confidence: 99%

Controlling the p-Type Conductivity and Composition Range for Bipolar Conduction in Ni_xCd_1–xO Alloys by Acceptor Doping

et al. 2020

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Oxide-based transparent p−n homojunctions are desirable for the development of transparent electronics. However, most oxide semiconductors are intrinsically n-type and to achieve p-type wide-gap oxide is still challenging. Previously, we have demonstrated that alloying a high-mobility n-type material such as CdO with p-type NiO can provide an avenue for electronic band engineering and consequently achieve bipolar conductivity in the midalloy composition. In this study, we synthesized O-rich Ni x Cd 1−x O alloys (Ni x Cd 1−x O 1+δ ) over the entire composition with Li and Cu doping using radio frequency (RF) magnetron sputtering at room temperature. We show that by Li and Cu doping the conductivity in the p-type regime of these alloys is improved, which also leads to a wider composition window for bipolar doping in Ni x Cd 1−x O. Specifically, by Li doping, the p-type alloy composition can be extended to x ≥ 0.3 so that the bipolar doping window is expanded to 0.30 ≤ x ≤ 0.52. Detailed measurements on electrical, structural, optical, and electronic properties suggest that Li is an effective acceptor, offering a promising way to improve the p-type conduction in Ni-rich Ni x Cd 1−x O alloys as well as to regulate the bipolar conductivity in this alloy system. A p-Ni 0.7 Cd 0.3 O:Li/n-Ni 0.45 Cd 0.55 O quasi-homojunction was fabricated and a rectification ratio ∼10 2 with an ideality factor of ∼2.9 was obtained. The demonstrated quasi-homojunction structure also showed >60% transmittance in the visible spectrum.

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“…We observe that Ga 2 O 3 (x = 0) shows the usual high transmittance of ≳80% in the entire spectra range. 68,69 However, the transmittance of alloys with x > 0 is lower for Li-doped films, and the magnitude of the reduction increases with x. For example, Li-doped alloy thin films with x ∼ 0.4 show an ∼12% decrease in transmission, whereas those with x ∼ 0.7 and x ∼ 1 show a larger decrease of ∼20 and 25%, respectively.…”

Section: The Journal Of Physical Chemistrymentioning

confidence: 99%

Efficient Acceptor Doping of Sputter-Deposited p-Type Ni_xGa_1–xO Rocksalt Alloy with Li

Ezeh

Egbo

2023

J. Phys. Chem. C

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Ga2O3 as an ultrawide band gap semiconductor has attracted much attention in high-power electronic applications, but its full potential and functionalities have been hampered by its inability to obtain reliable p-type materials. Previously, we demonstrated p-type Ga2O3 by alloying with NiO in an O-rich environment (Ni x Ga1–x O1+δ). This is attributed to the >1.8 eV upward movement of the valence band maximum (VBM) when the alloy forms a rocksalt structure for x ≳ 0.2, making the Ni vacancy (V Ni) acceptors to become shallow. Here, we improve the p-type conductivity of Ni x Ga1–x O1+δ by extrinsic p-type doping with Li by magnetron sputtering. While stoichiometric Ni x Ga1–x O alloys are highly resistive throughout the whole composition range, Li-doped Ni x Ga1–x O exhibits p-type conductivity with x > 0.4, confirming that despite the lack of a high V Ni concentration, Li is an effective acceptor in RS-Ni x Ga1–x O. The doping efficiency of Li is further improved in O-rich alloys Ni x Ga1–x O1+δ due to the enhanced incorporation of Li, so that p-type conducting Ni x Ga1–x O1+δ:Li alloys with Ni composition as low as x ∼ 0.2 is achieved. With Li doping, the ρ of Ni-rich alloys with x > 0.5 is <10 Ω·cm, which is over an order of magnitude lower than that in undoped alloys. The enhanced p-type conductivity of Ni x Ga1–x O1+δ:Li is in good agreement with the position of their Fermi level with respect to the VBM, as revealed by VB spectra from X-ray photoelectron spectroscopy measurements. With further optimization of the doping concentration, these p-type Ni x Ga1–x O1+δ:Li films can be exploited to form p–n junction structures on n-type Ga2O3.

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Room-Temperature-Synthesized High-Mobility Transparent Amorphous CdO–Ga₂O₃ Alloys with Widely Tunable Electronic Bands

Cited by 29 publications

References 57 publications

Complex amorphous oxides: property prediction from high throughput DFT and AI for new material search

Complex amorphous oxides: property prediction from high throughput DFT and AI for new material search

Controlling the p-Type Conductivity and Composition Range for Bipolar Conduction in Ni_xCd_1–xO Alloys by Acceptor Doping

Efficient Acceptor Doping of Sputter-Deposited p-Type Ni_xGa_1–xO Rocksalt Alloy with Li

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Room-Temperature-Synthesized High-Mobility Transparent Amorphous CdO–Ga2O3 Alloys with Widely Tunable Electronic Bands

Cited by 29 publications

References 57 publications

Complex amorphous oxides: property prediction from high throughput DFT and AI for new material search

Complex amorphous oxides: property prediction from high throughput DFT and AI for new material search

Controlling the p-Type Conductivity and Composition Range for Bipolar Conduction in NixCd1–xO Alloys by Acceptor Doping

Efficient Acceptor Doping of Sputter-Deposited p-Type NixGa1–xO Rocksalt Alloy with Li

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Product

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Room-Temperature-Synthesized High-Mobility Transparent Amorphous CdO–Ga₂O₃ Alloys with Widely Tunable Electronic Bands

Controlling the p-Type Conductivity and Composition Range for Bipolar Conduction in Ni_xCd_1–xO Alloys by Acceptor Doping

Efficient Acceptor Doping of Sputter-Deposited p-Type Ni_xGa_1–xO Rocksalt Alloy with Li