Tin-Assisted Synthesis of 
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 by Molecular Beam Epitaxy

Kracht, M.; Karg, Alexander; Schörmann, Jörg; Weinhold, Marcel; Zink, Daniel M.; Michel, Fabian; Rohnke, Marcus; Schowalter, Marco; Gerken, Beeke; Rosenauer, Andreas; Klar, Peter J.; Janek, Jürgen; Eickhoff, Martin

doi:10.1103/physrevapplied.8.054002

Cited by 135 publications

(93 citation statements)

References 22 publications

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“…The κ-phase of Ga2O3 has already been reported as thin film deposited by several different methods, including pulsed-laser deposition (PLD) [18][19][20][21][22][23][24][25] , halide vapor phase epitaxy 26,27 , metal-organic chemical vapor deposition [28][29][30][31][32][33] , metal-organic vapor phase epitaxy [34][35][36][37] , mist chemical vapor deposition (mist CVD) [38][39][40][41][42] , molecular beam epitaxy (MBE) 43,44 and others. Recently, one report even achieved conductive doping of this phase by Si or Sn incorporation, which is necessary for a variety of device applications 36 .…”

Section: Introductionmentioning

confidence: 99%

“…Recently, one report even achieved conductive doping of this phase by Si or Sn incorporation, which is necessary for a variety of device applications 36 . However, in PLD and MBE growth, tin is necessary as catalyst to stabilize the orthorhombic modification at all, but is not incorporated in the thin film layer as active donor element [18][19][20][23][24][25]44 . Further, several reports already deal with the alloying of this phase with indium 23,25,38 or aluminum 24,40 in a broad composition range, including bandgap engineering and the evolution of lattice constants.…”

Section: Introductionmentioning

confidence: 99%

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Band Offsets at κ-([Al,In]_xGa_1–x)₂O₃/MgO Interfaces

Schultz

Kneiß

Storm

et al. 2020

ACS Appl. Mater. Interfaces

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Conduction and valence band offsets are amongst the most crucial material parameters for semiconductor heterostructure device design, such as for high-electron mobility transistors or quantum-well infrared photodetectors. Due to its expected high spontaneous electrical polarization and the possibility of polarization doping at heterointerfaces similar to the AlGaN/InGaN/GaN system, the metastable orthorhombic κ-phase of Ga2O3 and its indium and aluminum alloy systems are a promising alternative for such device applications. However, respective band offsets to any dielectric are unknown, as well as the evolution of the bands within the alloy systems. We report on valence and conduction band offsets of orthorhombic κ-(AlxGa1-x)2O3 and κ-(InxGa1-x)2O3 thin films to MgO as reference dielectric by X-ray photoelectron spectroscopy. The thin films with compositions xIn ≤ 0.27 and xAl ≤ 0.55 were grown by pulsed laser deposition utilizing tin-doped and radially-segmented targets. The determined band alignments reveal the formation of a type I heterojunction to MgO for all compositions with conduction band offsets of at least 1.4 eV, providing excellent electron confinement. Only low valence band offsets with a maximum of ~300 meV were observed. Nevertheless, this renders MgO as promising gate dielectric for metaloxide-semiconductor transistors in the orthorhombic modification. We further found that the conduction band offsets in the alloy systems are mainly determined by the evolution of the bandgaps, which can be tuned by the composition in a wide range between 4.1 and 6.2 eV, since the energy position of the valence band maximum stays almost constant over the complete composition range investigated. Therefore, tunable conduction band offsets of up to 1.1 eV within the alloy systems allow for subniveau transition energies in (AlxGa1-x)2O3/(InxGa1-x)2O3/(AlxGa1x)2O3 quantum wells from the IR to the visible regime, which are promising for application in quantum-well infrared photodetectors.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Band Offsets at κ-([Al,In]_xGa_1–x)₂O₃/MgO Interfaces

Schultz

Kneiß

Storm

et al. 2020

ACS Appl. Mater. Interfaces

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“…Although it is beyond this article to evaluate the data in detail, both Raman spectra and the surface morphology investigated via SEM and AFM, respectively, confirm a more pronounced crystallinity after annealing . Especially Raman spectroscopy is known to very sensitively differentiate material phases or locate defect structures . Thus, the presumption of the conversion of amorphous material into β ‐Ga 2 O 3 throughout the discussion is further underlined.…”

Section: Resultsmentioning

confidence: 91%

“…For example, EFG can be used to produce even 4 inch‐diameter single‐crystal wafers . Thin films can be realized by a variety of techniques, chemical vapor deposition (CVD), metal‐organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), pulsed laser deposition (PLD), and sol–gel synthesis, among others. A topical review with focus on the progress in the synthesis of bulk as well as thin films of Ga 2 O 3 was recently given by Galazka …”

Section: Introductionmentioning

confidence: 99%

Progress in Sputter Growth of β‐Ga₂O₃ by Applying Pulsed‐Mode Operation

Schurig

Michel

Beyer

et al. 2020

Physica Status Solidi (a)

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β‐Ga2O3 thin films are deposited by pulsed radio‐frequency (RF) magnetron sputtering on c‐sapphire substrates, using a stoichiometric Ga2O3 target and a constant gas flux of an argon–oxygen mixture. Pulsed sputtering offers a way to overcome the restrictions of conventional sputtering. The parameters RF power and pulse duty cycle (PDC) are varied systematically to optimize the synthesis of Ga2O3 thin films. Subsequently, the resulting as‐deposited (AD) Ga2O3 layers are analyzed in terms of structural and optical properties and the results are compared with those on the samples treated by postdeposition rapid thermal annealing. Based on this analysis, the process parameters are evaluated in terms of β‐Ga2O3 formation. Postdeposition temperature treatments are found to yield a better crystal quality. However, a strong interdiffusion with the Al2O3 substrate is observed. The optical bandgap of the sputtered thin films is found to be quite independent of the RF sputtering power but to depend strongly on the PDC used, whereas the layer thickness rather strongly increases with both of those growth parameters. These evolutions are assigned to changes in the energy and ionic species of the plasma. Traces of GaOx‐related phases in addition to β‐Ga2O3 are found in the interphase between the growing thin films and the underlying substrate.

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“…It is a transparent conductive oxide (TCO) that has attracted strong interest due to its high chemical and thermal stability, wide transparency range (E g ≈ 4.9 eV) [17], controllable conductivity [18], excellent properties for high-power electronics due to its very high breakdown field [19,20] as well as its biocompatibility [21,22]. Nano-and microscale light sources allowing for wavelength tunability are needed as photonic building blocks in the micro-and nanoscale, such as light-emitting devices, light detectors, or active optical switches [23].…”

Section: Introductionmentioning

confidence: 99%

Modal Analysis of β−Ga2O3:Cr Widely Tunable Luminescent Optical Microcavities

et al. 2018

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Optical microcavities are key elements in many photonic devices, and those based on distributed Bragg reflectors (DBRs) enhance dramatically the end reflectivity, allowing for higher quality factors and finesse values. Besides, they allow for wide wavelength tunability, needed for nano-and microscale light sources to be used as photonic building blocks in the micro-and nanoscale. Understanding the complete behavior of light within the cavity is essential to obtaining an optimized design of properties and optical tunability. In this work, focused ion-beam fabrication of high refractive-index contrast DBR-based optical cavities within Ga 2 O 3 ∶Cr microwires grown and doped by the vapor-solid mechanism is reported. Room-temperature microphotoluminescence spectra show strong modulations from about 650 nm up to beyond 800 nm due to the microcavity resonance modes. Selectivity of the peak wavelength is achieved for two different cavities, demonstrating the tunability of this kind of optical system. Analysis of the confined modes is carried out by an analytical approximation and by finite-difference-time-domain simulations. A good agreement is obtained between the reflectivity values of the DBRs calculated from the experimental resonance spectra, and those obtained by finite-difference-time-domain simulations. Experimental reflectivities up to 70% are observed in the studied wavelength range and cavities, and simulations demonstrate that reflectivities up to about 90% could be reached. Therefore, Ga 2 O 3 ∶Cr high-reflectivity optical microcavities are shown as good candidates for single-material-based, widely tunable light emitters for micro-and nanodevices.

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Tin-Assisted Synthesis of ε−Ga2O3 by Molecular Beam Epitaxy

Cited by 135 publications

References 22 publications

Band Offsets at κ-([Al,In]_xGa_1–x)₂O₃/MgO Interfaces

Band Offsets at κ-([Al,In]_xGa_1–x)₂O₃/MgO Interfaces

Progress in Sputter Growth of β‐Ga₂O₃ by Applying Pulsed‐Mode Operation

Modal Analysis of β−Ga2O3:Cr Widely Tunable Luminescent Optical Microcavities

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Tin-Assisted Synthesis of ε−Ga2O3 by Molecular Beam Epitaxy

Cited by 135 publications

References 22 publications

Band Offsets at κ-([Al,In]xGa1–x)2O3/MgO Interfaces

Band Offsets at κ-([Al,In]xGa1–x)2O3/MgO Interfaces

Progress in Sputter Growth of β‐Ga2O3 by Applying Pulsed‐Mode Operation

Modal Analysis of β−Ga2O3:Cr Widely Tunable Luminescent Optical Microcavities

Contact Info

Product

Resources

About

Band Offsets at κ-([Al,In]_xGa_1–x)₂O₃/MgO Interfaces

Band Offsets at κ-([Al,In]_xGa_1–x)₂O₃/MgO Interfaces

Progress in Sputter Growth of β‐Ga₂O₃ by Applying Pulsed‐Mode Operation