The hot-wall metalorganic chemical vapor deposition (MOCVD) concept, previously shown to enable superior material quality and high performance devices based on wide bandgap semiconductors, such as Ga(Al)N and SiC, has been applied to the epitaxial growth of β-Ga 2 O 3 . Epitaxial β-Ga 2 O 3 layers at high growth rates (above 1 μm/h), at low reagent flows, and at reduced growth temperatures (740 °C) are demonstrated. A high crystalline quality epitaxial material on a c-plane sapphire substrate is attained as corroborated by a combination of x-ray diffraction, high-resolution scanning transmission electron microscopy, and spectroscopic ellipsometry measurements. The hot-wall MOCVD process is transferred to homoepitaxy, and single-crystalline homoepitaxial β-Ga 2 O 3 layers are demonstrated with a [Formula: see text]01 rocking curve width of 118 arc sec, which is comparable to those of the edge-defined film-fed grown ([Formula: see text]01) β-Ga 2 O 3 substrates, indicative of similar dislocation densities for epilayers and substrates. Hence, hot-wall MOCVD is proposed as a prospective growth method to be further explored for the fabrication of β-Ga 2 O 3 .
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From Salt to Electronics: Heteroepitaxy and GaAs Solar Cells
This paper presents work on the heteroepitaxy of salts, specifically fluorides, on semiconductors and heteroepitaxy of semiconductors on salts. Fluorides layers are deposited on commercial Gallium Arsenide (GaAs) wafers followed by the heteroepitaxial growth of GaAs using metal‐organic chemical vapor deposition (MOCVD). The fluoride layers consist of 2 lattice‐engineered layers of alkaline‐earth compounds to match with GaAs, and are used to sandwich another alkaline‐earth compound with higher water‐solubility as a sacrificial layer. The triple fluoride layers enable liftoff of free‐standing semiconductor films which can be further transferred to desirable substrates. 2D‐X‐ray Diffraction (2D‐XRD) measurements confirm epitaxial growth of both the fluorides and the subsequently grown GaAs films. Single junction (SJ) solar cell devices based on thus prepared films show a power conversion efficiency (PCE) of 10.3% under 1 sun illumination. After the completion of device fabrications, the GaAs film is lifted off from the substrate by a novel water‐assisted epitaxial liftoff (H2O‐ELO) technique and transferred to a cheaper substrate. The original GaAs wafer is recycled and reused twice. Devices based on reused substrates show no significant degradation in performance. The semiconductor‐salt‐semiconductor scheme has great implications in high‐performance, flexible, and large‐area electronics.
more » « less- NSF-PAR ID:
- 10371272
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials Interfaces
- Volume:
- 9
- Issue:
- 26
- ISSN:
- 2196-7350
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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