Selective area growth of GaN nanowires and nanofins by molecular beam epitaxy on heteroepitaxial diamond (001) substrates

Pantle, Florian; Becker, Fabian; Kraut, Max; Wörle, Simon; Hoffmann, Theresa; Artmeier, Sabrina; Stutzmann, M.

doi:10.1039/d1na00221j

Cited by 7 publications

(6 citation statements)

References 60 publications

(111 reference statements)

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“…The growth duration was 90 min. A detailed description of the NS fabrication process can be found in the literature [25][26][27][28]. The background pressure of the MBE system was in the 10 −10 mbar range.…”

Section: Methodsmentioning

confidence: 99%

Environmental sensitivity of GaN nanofins grown by selective area molecular beam epitaxy

Pantle

Wörle²,

Karlinger³

et al. 2023

Nanotechnology

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Nanostructures exhibit a large surface-to-volume ratio, which makes them sensitive to their ambient conditions. In particular, GaN nanowires and nanofins react to their environment as adsorbates influence their (opto-) electronic properties. Charge transfer between the semiconductor surface and adsorbed species changes the surface band bending of the nanostructures, and the adsorbates can alter the rate of non-radiative recombination in GaN. Despite the importance of these interactions with the ambient environment, the detailed adsorption mechanisms are still not fully understood. In this article, we present a systematic study concerning the environmental sensitivity of the electrical conductivity of GaN nanofins. We identify oxygen- and water-based adsorbates to be responsible for a quenching of the electrical current through GaN nanofins due to an increased surface band bending. Complementary contact potential difference measurements in controlled atmospheres on bulk m- and c-plane GaN reveal additional complexity with regard to water adsorption, for which surface dipoles might play an important role besides an increased surface depletion width. The sensitive reaction of the electrical parameters to the environment and surface condition underlines the necessity of a reproducible pre-treatment and/or surface passivation. The presented results help to further understand the complex adsorption mechanisms at GaN surfaces. Due to the sensitivity of the nanofin conductivity on the environment, such structures could perform well as sensing devices.

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Section: Methodsmentioning

confidence: 99%

Environmental sensitivity of GaN nanofins grown by selective area molecular beam epitaxy

Pantle

Wörle²,

Karlinger³

et al. 2023

Nanotechnology

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“…With careful optimization of our growth process, we develop nanostructures with dimensions <300 nm and ultra-smooth sidewalls. Hence, SAE-grown three-dimensional GaN nanostructures - wires, fins, rings, and curved features enable the fabrication of a wider range of electronic and photonic devices, such as fin field-effect transistors, lasers, and light-emitting diodes (LEDs). ,,, …”

Section: Introductionmentioning

confidence: 99%

“…Selective area epitaxy (SAE) , is a viable alternative to precisely control the size, position, shape, and density with an added advantage of controllability on III-nitride crystal planes, such as polar, semipolar and nonpolar facets of nanostructures. − The powerful SAE technique yields various types of nanostructures ranging from nanowires (NWs), nanofins (NFs), and nanorings (NRs). Until recently, it has remained challenging to understand the SAE kinetics and selectively grow nanostructures using different mask materials.…”

Section: Introductionmentioning

confidence: 99%

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Selective Area Epitaxy of GaN Nanostructures: MBE Growth and Morphological Analysis

Hasan

You

Ghosh

et al. 2023

Crystal Growth & Design

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This work presents the selective area epitaxy of GaN nanostructures grown on Ga-polar GaN/sapphire substrates by plasma-assisted molecular beam epitaxy. We demonstrate three types of nanostructures, including nanowires, nanofins, and nanorings on GaN-on-sapphire templates as well as investigate the ways of controlling their morphology, and orientation of sidewall plus top facets. A range of growth conditions including low to high Ga flux were employed during selective area epitaxy to develop these nanostructures with homogenous geometry and near vertical and smooth sidewalls. Using appropriate growth conditions and mask patterning orientations, nonpolar nanofin grids containing both/either m-/a-planes with as low as 260 nm fin width and up to six interconnects are demonstrated with smooth sidewalls. Based on these experimental results, we developed a growth model that takes different sidewall facets and orientations into account. The model generalizes the experimental results well and explains the growth conditions for the nanostructures. This study serves to advance the understanding of selective area epitaxy for defining complex III-nitride nanostructures that constitute an active area of research and development in the fields of nanotechnology and nanoscience.

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“…Prior to growth, the Ti masks were nitridated at 400 °C for 10 min and at 800 °C for 5 min with a nitrogen flux of 0.363 sccm and an RF power of 425 W to convert the Ti mask to the more stable TiNx. A more detailed description is provided in previous publications. − Growth of GaN NWs was carried out at substrate temperatures between 875 and 955 °C under nitrogen-rich growth conditions at a Ga flux of 1.0 × 10 –6 mbar beam equivalent pressure (BEP) for 90 min while maintaining the nitrogen flux. GaN NWs were grown on a GaN template on c -plane sapphire (Saint-Gobain Lumilog) for further analysis by TEM, while NWs used for Raman measurements were grown on a Si(111) substrate.…”

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confidence: 99%

Atomic Layer Deposition and Strain Analysis of Epitaxial GaN-ZnO Core–Shell Nanowires

et al. 2023

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We demonstrate the epitaxial coating of GaN NWs with an epitaxial ZnO shell by atomic layer deposition at 300 °C. Scanning transmission electron microscopy proves a sharp and defect-free coherent interface. The strain in the core–shell structure due to the lattice mismatch and different thermal expansion coefficients of GaN and ZnO was analyzed using 4D-STEM strain mapping and Raman spectroscopy and compared to theoretical calculations. The results highlight the outstanding advantages of epitaxial shell growth using atomic layer deposition, e.g., conformal coating and precise thickness control.

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Selective area growth of GaN nanowires and nanofins by molecular beam epitaxy on heteroepitaxial diamond (001) substrates

Abstract: GaN-on-diamond is a promising route towards reliable high-power transistor devices with outstanding performances due to a better heat management replacing common GaN-on-SiC technologies. Nevertheless, the implementation of GaN-on-diamond remains challenging....

Cited by 7 publications

References 60 publications

Environmental sensitivity of GaN nanofins grown by selective area molecular beam epitaxy

Environmental sensitivity of GaN nanofins grown by selective area molecular beam epitaxy

Selective Area Epitaxy of GaN Nanostructures: MBE Growth and Morphological Analysis

Atomic Layer Deposition and Strain Analysis of Epitaxial GaN-ZnO Core–Shell Nanowires

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