Si-doped β-phase (010) Ga2O3 epi-films with fast growth rates were comprehensively investigated using trimethylgallium (TMGa) as the Ga precursor via metalorganic chemical vapor deposition (MOCVD). Two main challenges facing the MOCVD growth of thick (010) β-Ga2O3 films with fast growth rates include high impurity carbon (C) incorporation and rough surface morphologies due to the formation of imbedded 3D pyramid-shaped structures. In this work, two different categories of oxygen source (high-purity O2 > 99.9999% and O2* with 10 ppm of [H2O]) were used for β-Ga2O3 MOCVD growth. Our study revealed that the size and density of the 3D defects in the β-Ga2O3 epi-films were significantly reduced when the O2* was used. In addition, the use of off-axis (010) Ga2O3 substrates with 2° off-cut angle leads to further reduction of defect formation in β-Ga2O3 with fast growth rates. To suppress C incorporation in MOCVD β-Ga2O3 grown with high TMGa flow rates, our findings indicate that high O2 (or O2*) flow rates are essential. Superior room temperature electron mobilities as high as 110–190 cm2/V·s were achieved for β-Ga2O3 grown using O2* (2000 sccm) with a growth rate of 4.5 μm/h (film thickness of 6.3 μm) within the doping range of 1.3 × 1018–7 × 1015 cm−3. The C incorporation is significantly suppressed from ∼1018 cm−3 to <5 × 1016 cm−3 ([C] detection limit) for β-Ga2O3 grown using high O2 (O2*) flow rate of 2000 sccm. Results from this work will provide guidance on developing high-quality, thick β-Ga2O3 films required for high power electronic devices with vertical configurations. 
                        more » 
                        « less   
                    
                            
                            High growth rate metal organic chemical vapor deposition grown Ga2O3 (010) Schottky diodes
                        
                    
    
            We report on the growth of Si-doped homoepitaxial β-Ga2O3 thin films on (010) Ga2O3 substrates via metal-organic chemical vapor deposition (MOCVD) utilizing triethylgallium (TEGa) and trimethylgallium (TMGa) precursors. The epitaxial growth achieved an impressive 9.5 μm thickness at 3 μm/h using TMGa, a significant advance in material growth for electronic device fabrication. This paper systematically studies the Schottky barrier diodes fabricated on the three MOCVD-grown films, each exhibiting variations in the epilayer thickness, doping levels, and growth rates. The diode from the 2 μm thick Ga2O3 epilayer with TEGa precursor demonstrates promising forward current densities, the lowest specific on-resistance, and the lowest ideality factor, endorsing TEGa’s potential for MOCVD growth. Conversely, the diode from the 9.5 μm thick Ga2O3 layer with TMGa precursor exhibits excellent characteristics in terms of lowest leakage current, highest on-off ratio, and highest reverse breakdown voltage of −510 V without any electric field management, emphasizing TMGa’s suitability for achieving high growth rates in Ga2O3 epilayers for vertical power electronic devices. 
        more » 
        « less   
        
    
    
                            - PAR ID:
- 10545895
- Publisher / Repository:
- JVST
- Date Published:
- Journal Name:
- Journal of Vacuum Science & Technology A
- Volume:
- 42
- Issue:
- 4
- ISSN:
- 0734-2101
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
- 
            
- 
            Background carbon incorporation and film cracking issue in (001) β-Ga2O3 films grown by metalorganic chemical vapor deposition (MOCVD) are investigated. Quantitative secondary ion mass spectrometry analysis shows that increasing the O2 flow rate significantly reduces carbon concentration, suggesting the importance of optimizing the VI/III ratio and growth temperature to achieve low compensation and controllable doping in MOCVD of (001) Ga2O3 films. MOCVD growth of (001) β-Ga2O3 films with a film thickness of 25 μm at a growth rate of 10 μm/h is achieved. However, film cracking remains a persistent challenge. Reducing the growth rate by adjusting the trimethylgallium (TMGa) flow rate or increasing chamber pressure effectively suppresses cracking, but it results in slower growth rates. In addition, lower growth temperature and high chamber pressure can help suppressing surface reconstruction and reduce the formation of cracking. Buffer layers grown at 850 °C, 100 Torr, and 58 μmol/min of TMGa significantly improve surface morphology of drift layers. Moreover, the use of AlGaO buffer layers with 8% of Al and a thickness of ∼130 nm leads to a lower crack density. X-ray rocking curve analysis confirms high crystalline quality at a growth rate of 10 μm/h, with no degradation observed from the introduction of an AlGaO buffer layer. These optimized growth conditions effectively improve surface smoothness and minimize defects. Results from this work provide fundamental insights in MOCVD epitaxy of β-Ga2O3 on (001) Ga2O3 substrates, revealing the opportunities and challenges of MOCVD (001) β-Ga2O3 thin films with fast growth rates for high-power electronic device technology.more » « less
- 
            In this Letter, the role of background carbon in metalorganic chemical vapor deposition (MOCVD) β-Ga2O3 growth using trimethylgallium (TMGa) as the Ga precursor was investigated. The quantitative C and H incorporations in MOCVD β-Ga2O3 thin films grown at different growth rates and temperatures were measured via quantitative secondary ion mass spectroscopy (SIMS). The SIMS results revealed both [C] and [H] increase as the TMGa molar flow rate/growth rate increases or growth temperature decreases. The intentional Si incorporation in MOCVD β-Ga2O3 thin films decreases as the growth rate increases or the growth temperature decreases. For films grown at relatively fast growth rates (GRs) (TMGa > 58 μmol/min, GR > 2.8 μm/h) or relatively low temperature (<950 °C), the [C] increases faster than that of the [H]. The experimental results from this study demonstrate the previously predicted theory—H can effectively passivate the compensation effect of C in n-type β-Ga2O3. The extracted net doping concentration from quantitative SIMS {[Si]-([C]-[H])} agrees well with the free carrier concentration measured from Hall measurement. The revealing of the role of C compensation in MOCVD β-Ga2O3 and the effect of H incorporation will provide guidance on designing material synthesis for targeted device applications.more » « less
- 
            Growing a thick high-quality epitaxial layer on the β-Ga2O3 substrate is crucial in commercializing β-Ga2O3 devices. Metal organic chemical vapor deposition (MOCVD) is also well-established for the large-scale commercial growth of β-Ga2O3 and related heterostructures. This paper presents a systematic study of the Schottky barrier diodes fabricated on two different Si-doped homoepitaxial β-Ga2O3 thin films grown on Sn-doped (001) and (010) β-Ga2O3 substrates by MOCVD. X-ray diffraction analysis of the MOCVD-grown sample, room temperature current density–voltage data for different Schottky diodes, and C–V measurements are presented. Diode characteristics, such as ideality factor, barrier height, specific on-resistance, and breakdown voltage, are studied. Temperature dependence (170–360 K) of the ideality factor, barrier height, and Poole–Frenkel reverse leakage mechanism are also analyzed from the J–V–T characteristics of the fabricated Schottky diodes.more » « less
- 
            Growths of monoclinic (AlxGa1−x)2O3thin films up to 99% Al contents are demonstrated via metalorganic chemical vapor deposition (MOCVD) using trimethylgallium (TMGa) as the Ga precursor. The utilization of TMGa, rather than triethylgallium, enables a significant improvement of the growth rates (>2.5 μm h−1) of β‐(AlxGa1−x)2O3thin films on (010), (100), and (01) β‐Ga2O3substrates. By systematically tuning the precursor molar flow rates, growth of coherently strained phase pure β‐(AlxGa1−x)2O3films is demonstrated by comprehensive material characterizations via high‐resolution X‐ray diffraction (XRD) and atomic‐resolution scanning transmission electron microscopy (STEM) imaging. Monoclinic (AlxGa1−x)2O3films with Al contents up to 99, 29, and 16% are achieved on (100), (010), and (01) β‐Ga2O3substrates, respectively. Beyond 29% of Al incorporation, the (010) (AlxGa1−x)2O3films exhibit β‐ to γ‐phase segregation. β‐(AlxGa1−x)2O3films grown on (01) β‐Ga2O3show local segregation of Al along (100) plane. Record‐high Al incorporations up to 99% in monoclinic (AlxGa1−x)2O3grown on (100) Ga2O3are confirmed from XRD, STEM, electron nanodiffraction, and X‐ray photoelectron spectroscopy measurements. These results indicate great promises of MOCVD development of β‐(AlxGa1−x)2O3films and heterostructures with high Al content and growth rates using TMGa for next‐generation high‐power and high‐frequency electronic devices.more » « less
 An official website of the United States government
An official website of the United States government 
				
			 
					 
					
 
                                    