Self-trapped hole and impurity-related broad luminescence in <i>β</i>-Ga2O3

Frodason, Ymir Kalmann; Johansen, K. M.; Vines, Lasse; Varley, Joel B.

doi:10.1063/1.5140742

Cited by 104 publications

(65 citation statements)

References 58 publications

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“…It is noticeable that the UV region is fitted by two UV Gaussian peaks, because photogenerated holes can be self‐trapped by two different oxygen sites. [ 48,49 ] The ratio of the total integrated area of BL and GL to UV represents the proportion of defects in the β‐Ga 2 O 3 film. The ratio decreases with increase in the growth temperature, as shown in Figure 9b.…”

Section: Resultsmentioning

confidence: 99%

Investigation of β‐Ga₂O₃ Film Growth Mechanism on c‐Plane Sapphire Substrate by Ozone Molecular Beam Epitaxy

Feng

Cheng

et al. 2020

Physica Status Solidi (a)

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Growth mechanism and temperature of monoclinic gallium oxide (β‐Ga2O3) films grown by ozone molecular beam epitaxy (MBE) are investigated herein. Phase‐pure (2true¯01) β‐Ga2O3 films can be grown on c‐plane sapphire substrates when the growth temperature exceeds 500 °C, and the grain size increases with the increase in the growth temperature. Sixfold rotational domains are obtained based on the epitaxial relationships (Ga2O3 < 010>//Al2O3<11true¯00> and Ga2O3 < 102>//Al2O3 < 11true2¯0>). For the film grown at 700 °C, the threefold facets are observed for the first time, which are resulted from the easy‐cleaved (100) plane and rotational domains. In addition, the cathodoluminescence spectra of the β‐Ga2O3 films show that the proportion of ultraviolet emission increases with the increase in the growth temperature, which is attributed to the modulation of defect. Finally, the growth rate can be modulated by the ratio of Ga flux and ozone pressure. A reference is provided for heteroepitaxy of β‐Ga2O3 films and better understanding of the ozone MBE growth mechanism of oxides.

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Section: Resultsmentioning

confidence: 99%

Investigation of β‐Ga₂O₃ Film Growth Mechanism on c‐Plane Sapphire Substrate by Ozone Molecular Beam Epitaxy

Feng

Cheng

et al. 2020

Physica Status Solidi (a)

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“…Hybrid functional calculations show that self-trapped holes and many extrinsic defects can give rise to very broad luminescence bands 18 [Xe]4f 14 5d 5 2 T 2 (I) split by spin-orbital coupling:…”

Section: Icpmsmentioning

confidence: 99%

On the origin of red luminescence from iron-doped β-Ga2O3 bulk crystals

Sun

Ooi

Dickens

et al. 2020

Applied Physics Letters

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Currently, Fe doping in the ~10 18 cm-3 range is the most widely-available method for producing semi-insulating single crystalline-Ga 2 O 3 substrates. Red luminescence features have been reported from multiple types of Ga 2 O 3 samples including Fe-doped-Ga 2 O 3 , and attributed to Fe or N O. Herein, however, we demonstrate that the high-intensity red luminescence from Fe-doped β-Ga 2 O 3 commercial substrates consisting of two sharp peaks at 689 nm and 697 nm superimposed on a broader peak centered at 710 nm originates from Cr impurities present at a concentration near 2 ppm. The red emission exhibits twofold symmetry, peaks in intensity for excitation near absorption edge, seems to compete with Ga 2 O 3 emission at higher excitation energy and appears to be intensified in the presence of Fe. Based on polarized absorption, luminescence observations and Tanabe-Sugano diagram analysis, we propose a resonant energy transfer of photogenerated carriers in-Ga 2 O 3 matrix to octahedrally-coordinated Cr 3+ to give red luminescence, possibly also sensitized by Fe 3+ .

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“…I – V characteristics in Figure 9 have a slight shift (≈−0.3 V) of current minima in the dark state, which possibly attributed to the charge trapping and de‐trapping at the metal/Ga 2 O 3 interface, a well‐known phenomenon for Ga 2 O 3 . [ 33 ] Our PDs have Schottky contacts at the front side and ohmic at the backside. When PDs are under the forward bias or UV illumination, before measuring the dark current, the holes may trap near the Schottky junction via self‐trapping [ 33 ] and or at deep level acceptor states.…”

Section: Resultsmentioning

confidence: 99%

“…[ 33 ] Our PDs have Schottky contacts at the front side and ohmic at the backside. When PDs are under the forward bias or UV illumination, before measuring the dark current, the holes may trap near the Schottky junction via self‐trapping [ 33 ] and or at deep level acceptor states. This may be the reason why we observe the shift in the I – V measurements for some devices, because the density of deep level acceptor levels is not the same for all the samples.…”

Section: Resultsmentioning

confidence: 99%

High Figure‐of‐Merit Gallium Oxide UV Photodetector on Silicon by Molecular Beam Epitaxy: A Path toward Monolithic Integration

Mukhopadhyay

Hatipoglu

Sakthivel

et al. 2021

Advanced Photonics Research

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A high figure‐of‐merit UV‐C solar‐blind photodetector (PD) fabricated from thin‐film beta‐gallium oxide (β‐Ga2O3) grown on n‐Si substrates by plasma‐assisted molecular beam epitaxy is demonstrated. Film growth sequences for nucleation of Ga2O3 on (100)‐ and (111)‐oriented Si substrates are developed, and the influence of crucial growth parameters is systematically investigated, namely, substrate temperature, oxygen flow rate, and plasma power on the functional properties of the PDs. The PDs show an ultra‐high responsivity of 837 A W−1 and a fast ON/OFF time below 4 ms at −5 V. In addition, they display strong rectifying properties and a sharp cutoff below 280 nm with the average responsivities between 10 and 80 A W−1, a detectivity on the order of 1010 Jones, and rise/fall times between 4 and 500 ms. High photoconductive gain is likely to be due to the mid‐bandgap donor/acceptor defect levels, including oxygen vacancies in the form of self‐trapped holes. It is demonstrated that these defect levels can be modified by controlling the growth conditions, thereby allowing for tailoring of the PD characteristics for specific applications. The methodology represents a cost‐effective solution over homoepitaxial approaches, with characteristics that meet or exceed those reported previously, offering new possibilities for on‐wafer integration with Si opto‐electronics.

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Self-trapped hole and impurity-related broad luminescence in β-Ga2O3

Abstract: Self-trapped hole and impurity-related broad luminescence in β-Ga 2 O 3

Cited by 104 publications

References 58 publications

Investigation of β‐Ga₂O₃ Film Growth Mechanism on c‐Plane Sapphire Substrate by Ozone Molecular Beam Epitaxy

Investigation of β‐Ga₂O₃ Film Growth Mechanism on c‐Plane Sapphire Substrate by Ozone Molecular Beam Epitaxy

On the origin of red luminescence from iron-doped β-Ga2O3 bulk crystals

High Figure‐of‐Merit Gallium Oxide UV Photodetector on Silicon by Molecular Beam Epitaxy: A Path toward Monolithic Integration

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Self-trapped hole and impurity-related broad luminescence in β-Ga2O3

Abstract: Self-trapped hole and impurity-related broad luminescence in β-Ga 2 O 3

Cited by 104 publications

References 58 publications

Investigation of β‐Ga2O3 Film Growth Mechanism on c‐Plane Sapphire Substrate by Ozone Molecular Beam Epitaxy

Investigation of β‐Ga2O3 Film Growth Mechanism on c‐Plane Sapphire Substrate by Ozone Molecular Beam Epitaxy

On the origin of red luminescence from iron-doped β-Ga2O3 bulk crystals

High Figure‐of‐Merit Gallium Oxide UV Photodetector on Silicon by Molecular Beam Epitaxy: A Path toward Monolithic Integration

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Product

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Investigation of β‐Ga₂O₃ Film Growth Mechanism on c‐Plane Sapphire Substrate by Ozone Molecular Beam Epitaxy

Investigation of β‐Ga₂O₃ Film Growth Mechanism on c‐Plane Sapphire Substrate by Ozone Molecular Beam Epitaxy