Real-time monitoring and control of nitride growth rates by Metal Modulated Epitaxy

Averett, Kent L.; Hatch, John B.; Eyink, Kurt G.; Bowers, Cynthia T.; Mahalingam, Krishnamurthy

doi:10.1016/j.jcrysgro.2019.04.008

Cited by 2 publications

(2 citation statements)

References 34 publications

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“…Because secondary ion mass spectroscopy (SIMS) indicates oxygen impurity incorporation due to regrowth on GaN templates extends ∼300 nm into the film, the results are likely influenced by the oxygen contamination from the MME/HVPE GaN regrowth interface, making some metrics lower than found elsewhere for thicker films . III/V calculations during growths were recorded from in situ RHEED transients according to the process described above and described elsewhere. , …”

Section: Resultsmentioning

confidence: 99%

Comprehensive Analysis of Metal Modulated Epitaxial GaN

Ahmad

Motoki

Clinton

et al. 2020

ACS Appl. Mater. Interfaces

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While metal modulated epitaxy (MME) has been shown useful for hyperdoping, where hole concentrations 40 times higher than other techniques have been demonstrated, and the ability to control phase separation in immiscible III-nitrides, the complexity of the dynamically changing surface conditions during the cyclic growth is poorly understood. While MME is capable of superb crystal quality, performing MME in an improper growth regime can result in defective material. These complications have made the transfer of MME knowledge challenging. This work provides a comprehensive study of the conditions necessary for achieving the benefits of MME while avoiding undesirable defects. The effects of growth temperature, Ga/N ratio, and excess Ga dose per MME growth cycle on the morphological, structural, electronic, and optical properties of unintentionally doped (UID) MME grown gallium nitride (GaN) have been investigated. Optimal structural and electrical quality were achieved for GaN films grown at ∼650 °C, at pre-bilayer Ga coverage and at the moderate droplet regime. However, high defect concentrations were observed at the lowest growth temperatures, and counter to traditional MBE, as the excess Ga dose transitioned from bilayer coverage to the low droplet regime. Optoelectronic properties were optimal for films grown at intermediate growth temperatures, an excess Ga dose condition just before the droplet formation, and, at a III/V ratio of 1.3. Optimization of growth temperatures, Ga/N ratios, and excess Ga dose results in a range of growth conditions achieving smooth surfaces, step-flow surface morphology, and high crystalline quality films with low threading dislocation densities, allowing researchers to utilize the extensive advantages of MME.

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Section: Resultsmentioning

confidence: 99%

Comprehensive Analysis of Metal Modulated Epitaxial GaN

Ahmad

Motoki

Clinton

et al. 2020

ACS Appl. Mater. Interfaces

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“…The N * treatment time (τ 2 + τ 3 ), determined when the RHEED intensity recovers to its original value, increased from 19 to 60 s as Al flux increased from 1.5 × 10 −7 to 1.8 × 10 −7 Torr. This is attributed to the Al droplets on the surface which act as the reservoir of Al atoms, feeding Al back to the bilayer and thus maintaining two MLs Al coverage [28]. Obviously, τ 2 is determined by the amount of Al droplets, but In the stage I, the slightly bright and streaky RHEED pattern is due to the fact that Al adatoms absorb on the surface and gradually form the two MLs Al coverage.…”

Section: Resultsmentioning

confidence: 99%

Step-flow growth of Al droplet free AlN epilayers grown by plasma assisted molecular beam epitaxy

Li¹,

Li²,

Zhou³

et al. 2022

J. Phys. D: Appl. Phys.

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We have investigated an Al modulation epitaxy (AME) method to obtain step-flow growth of Al droplet free AlN layers by plasma assisted molecular beam epitaxy (MBE). At the usual growth temperature of (Al)GaN/AlN heterostructures, Al atom migration and desorption rate are very low and consequently it is very difficult to avoid the formation of Al droplets on AlN growth front by conventional MBE growth method. By adopting the AME growth method, such a difficulty has been effectively overcome. and step flow growth mode of AlN has been clearly observed. By optimizing the AME growth time sequence, namely, AlN growth time and N radical beam treatment time, Al droplet free AlN layers with step flow growth characteristics have been obtained, with atomic flat surfaces and an average atomic step width of ~118 nm at 970~1000 oC, which is still suitable to grow (Al)GaN/AlN heterostructures by MBE.

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Real-time monitoring and control of nitride growth rates by Metal Modulated Epitaxy

Cited by 2 publications

References 34 publications

Comprehensive Analysis of Metal Modulated Epitaxial GaN

Comprehensive Analysis of Metal Modulated Epitaxial GaN

Step-flow growth of Al droplet free AlN epilayers grown by plasma assisted molecular beam epitaxy

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