β-phase gallium oxide (Ga2O3) is an emerging ultrawide bandgap (UWBG) semiconductor with a bandgap energy of ∼ 4.8 eV and a predicted high critical electric field strength of ∼8 MV/cm, enabling promising applications in next generation high power electronics and deep ultraviolet optoelectronics. The advantages of Ga2O3 also stem from its availability of single crystal bulk native substrates synthesized from melt, and its well-controllable n-type doping from both bulk growth and thin film epitaxy. Among several thin film growth methods, metalorganic chemical vapor deposition (MOCVD) has been demonstrated as an enabling technology for developing high-quality epitaxy of Ga2O3 thin films, (AlxGa1−x)2O3 alloys, and heterostructures along various crystal orientations and with different phases. This tutorial summarizes the recent progresses in the epitaxial growth of β-Ga2O3 thin films via different growth methods, with a focus on the growth of Ga2O3 and its compositional alloys by MOCVD. The challenges for the epitaxial development of β-Ga2O3 are discussed, along with the opportunities of future works to enhance the state-of-the-art device performance based on this emerging UWBG semiconductor material system.
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Improving crystal quality of β -phase MgGaO thin films by using low-temperature homo-buffer layer
Ultra-wide bandgap (UWBG) semiconductors are promising for many applications, such as power electronics and deep-ultraviolet photonics. In this research, UWBG β-phase magnesium gallium oxide (MgGaO) thin films with a bandgap of 5.1 eV were grown using low-temperature homo-buffer layers in a plasma-assisted molecular beam epitaxy system. The role of the growth temperature and thickness of low-temperature buffer layer on the quality of the active layer was studied using x-ray diffraction and transmission electron microscopy and by analyzing the properties of metal–semiconductor–metal photodetector devices based on these films. It is found that lower buffer growth temperature at 300 °C leads to higher crystal quality of active layer. For the same low buffer growth temperature, different crystal quality in the active layer is attained with different buffer layer thickness. A buffer layer thickness at 40 nm has the best active layer quality with the highest photo current under 265 nm illumination and long decay time as a result of reduced recombination of photo-generated carriers through fewer defects in the active layer.
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- Award ID(s):
- 2105566
- PAR ID:
- 10416109
- Date Published:
- Journal Name:
- Applied Physics Letters
- Volume:
- 122
- Issue:
- 21
- ISSN:
- 0003-6951
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Article Highlights High quality diamond film with minimum surface roughness and ~93% oriented grains along (110) crystallographic direction is grown on Si substrate using a thin 5 to 20 nm nickel layer.
A detailed report on the formation of different phases of nickel silicide, its stability with different temperature, and its role for diamond film texturing at HFCVD growth condition is presented.
A diamond growth model on Si substrate with Ni interlayer to grow high quality-oriented diamond film is established.
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1063/5.0147948
