Numerical and experimental analysis of ammonothermal crystal growth configurations and their impact on the temperature field along the autoclave wall

Wostatek T, Zenk M, Friedrich J, Schimmel S (2025)

Publication Language: English

Publication Type: Conference contribution, Abstract of a poster

Publication year: 2025

Pages Range: 532-533

Conference Proceedings Title: ABSTRACT BOOKLET ICNS 15

Event location: Malmö SE

Open Access Link: https://files.mkon.nu/fmfiles/file/Abstractbook_ICNS15_020725_updated-1.pdf

Abstract

GaN devices manufactured on high-quality GaN substrate materials can open the door to new markets [1]. Amongst all existing bulk GaN growth techniques, the ammonothermal method delivers the highest structural quality [2]. Accordingly, GaN-on-ammonothermal GaN diodes demonstrate an outstanding breakdown voltage to on-resistance performance in benchmark tests [3]. So far, ammonothermal GaN has not yet reached the mass market and many questions on the process understanding are still pending [2].

S. Schimmel et al. showed that the temperature distribution and fluid flow inside the ammonothermal reactor (autoclave) are very sensitive to the temperature distribution along the autoclave wall [4]. The temperature distribution along the autoclave wall depends strongly on the actual ammonothermal configuration. A common configuration is a cylindrical autoclave in a multi-zone furnace, which in turn is placed in a type of an enclosure [5]. These components and their combination vary noticeably in the literature.

In this contribution, a comparison of different ammonothermal configurations will be given. Different autoclave materials (alloy 718, 282, 41 and TZM) and enclosure types (sealed with low N2 exchange rate, not sealed with high air exchange rate) will be compared. Beyond that, the effect of different configurations of a heat sink in the baffle region (between the growth and dissolution region) will be studied. Numerical simulations of the thermal field using the multi-physics software CrysMAS (developed by Fraunhofer IISB) have been carried out for the different configurations. In addition, experiments were conducted for verification and validation. The simulated heater powers are in reasonable agreement with the experiments. The heat losses depend strongly on the gas exchange rates. Major heat losses occur at the head assembly and the heat sink in the baffle region. These have a strong effect on the temperature distribution along the autoclave wall.


References

[1] N. Stoddard and S. Pimputkar, Crystals 13, 1004, 2023.

[2] R. Kucharski et al., J. Appl. Phys. 128, 050902, 2020.

[3] T. Pu et al., Nanoscale Res. Lett. 16.1, 101, 2021.

[4] S. Schimmel et al., Cystals 11, 254, 2021.

[5] T. Wostatek et al., Materials 17, 3104, 2024.

Authors with CRIS profile

Thomas Wostatek Lehrstuhl für Elektronische Bauelemente Saskia Schimmel Lehrstuhl für Elektronische Bauelemente

Related research project(s)

Emmy Noether-Programme „Novel nitride materials for electronic devices“ (1st period of funding) Aug. 1, 2023 - July 31, 2026

Involved external institutions

Fraunhofer-Institut für Integrierte Systeme und Bauelementetechnologie (IISB) DE Germany (DE)

How to cite

APA:

Wostatek, T., Zenk, M., Friedrich, J., & Schimmel, S. (2025, July). Numerical and experimental analysis of ammonothermal crystal growth configurations and their impact on the temperature field along the autoclave wall. Poster presentation at International Conference on Nitride Semiconductors - ICNS-15, Malmö, SE.

MLA:

Wostatek, Thomas, et al. "Numerical and experimental analysis of ammonothermal crystal growth configurations and their impact on the temperature field along the autoclave wall." Presented at International Conference on Nitride Semiconductors - ICNS-15, Malmö Ed. MIKON, 2025.

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