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Molecular beam homoepitaxy on bulk AlN enabled by aluminum-assisted surface cleaning
摘要： We compare the effectiveness of in situ thermal cleaning with that of Al-assisted cleaning of native surface oxides of bulk AlN for homoepitaxial growth by molecular beam epitaxy. Thermal deoxidation performed at 1450 (cid:2)C in vacuum results in voids in the AlN substrate. On the other hand, Al-assisted deoxidation at (cid:3)900(cid:2)C results in high-quality AlN homoepitaxy, evidenced by clean and wide atomic terraces on the surface and no extended defects at the growth interface. This study shows that Al-assisted in situ deoxidation is effective in removing native oxides on AlN, providing a clean surface to enable homoepitaxial growth of AlN and its heterostructures; furthermore, it is more attractive over thermal deoxidation, which needs to be conducted at much higher temperatures due to the strong bonding strength of native oxides on AlN.
关键词： surface cleaning,homoepitaxy,molecular beam epitaxy,aluminum-assisted cleaning,AlN
更新于2025-09-23 15:21:01
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Gallium Oxide || MBE growth and characterization of gallium oxide
摘要： Gallium oxide (Ga2O3) is an ultrawide bandgap (UWBG) oxide semiconductor with an indirect bandgap of 4.5–5.2 eV. The beta-phase (β-Ga2O3) is the commonly regarded as most stable of the several crystalline phases (or polymorphs) of Ga2O3. Because of its wide bandgap, it is transparent from ultraviolet to visible wavelengths. It had first been widely explored as a transparent conductive oxide (TCO) for optical devices such as light-emitting diodes. Also, it has been used as a gate dielectric in metal oxide semiconductor (MOS) structures in GaAs. The β-Ga2O3 can be synthesized by melt growth techniques such as Czochraski, floating zone (FZ), and edge-defined film-fed growth (EFG) at atmospheric pressure which can provide inexpensive large area bulk substrates. The commercial availability of large area Ga2O3 substrates is an important advantage over GaN and similar group III-N compound semiconductors in many potential electrical and optical device applications. Besides material benefit of UWBG, these substrates provide a high-quality crystalline platform for power electronics devices that require higher crystalline quality, low-defect density material with precise doping control capabilities.
关键词： β-Ga2O3,MBE growth,Gallium oxide,ultrawide bandgap,heteroepitaxy,homoepitaxy
更新于2025-09-09 09:28:46
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Faceting and metal-exchange catalysis in (010) β-Ga <sub/>2</sub> O <sub/>3</sub> thin films homoepitaxially grown by plasma-assisted molecular beam epitaxy
摘要： We here present an experimental study on (010)-oriented β-Ga2O3 thin films homoepitaxially grown by plasma assisted molecular beam epitaxy. We study the effect of substrate treatments (i.e., O-plasma and Ga-etching) and several deposition parameters (i.e., growth temperature and metal-to-oxygen flux ratio) on the resulting Ga2O3 surface morphology and growth rate. In situ and ex-situ characterizations identified the formation of (110) and (ˉ110)-facets on the nominally oriented (010) surface induced by the Ga-etching of the substrate and by several growth conditions, suggesting (110) to be a stable (yet unexplored) substrate orientation. Moreover, we demonstrate how metal-exchange catalysis enabled by an additional In-flux significantly increases the growth rate (>threefold increment) of monoclinic Ga2O3 at high growth temperatures, while maintaining a low surface roughness (rms < 0.5 nm) and preventing the incorporation of In into the deposited layer. This study gives important indications for obtaining device-quality thin films and opens up the possibility to enhance the growth rate in β-Ga2O3 homoepitaxy on different surfaces [e.g., (100) and (001)] via molecular beam epitaxy.
关键词： molecular beam epitaxy,metal-exchange catalysis,surface morphology,homoepitaxy,β-Ga2O3
更新于2025-09-04 15:30:14