Optimization of gas flow uniformity in enhancement of Metal Organic Chemical Vapor Deposition growth for III-nitrides

• Main Author: Olsson, Kevin
• Format: Others
• Language: English
• Published: Linköpings universitet, Halvledarmaterial 2019
• Subjects: material science; mocvd; gan; semiconductors; gallium; nitride; fluid dynamics; termoelements; thermocouple; injector; heat transfer; thermal distribution; graphite; HEMT; III-nitrides; hot-wall MOCVD system; GaN-on-SiC; gas flow profile; laminar flow; Other Materials Engineering; Annan materialteknik
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-157378

The thesis focuses on the gas flow profile optimization of a non-conventional injector in a hot-wall MOCVD system. The injector’s gas flow profile is simulated with CFD and demonstrates awell-behaved laminar flow with a parabolic profile. To ensure the theory is in coherence with the reality, a qualitative study with five thermocouples in a test graphite piece of the was performed. First the thesis will take you through an introduction of the semiconductor field to arrive in a problem formulation. Then you will read about the principles of MOCVD systems, fluid dynamics principles and thermocouple theory. The experiment’s way of approach is thendescribed through all steps from blue print to results. A discussion about the result and the conclusion will be read before the proposals of future work based on the thesis work. The laminar flow is confirmed according to the resulting data and the limitations of the system is set to two different cases depending on background temperature. At 1000 °C a laminar flow is strongly indicated to be obtained at position 3A, closest to the growth area, within the gas flow range of 25 SLM regardless of background pressure, except for 700 mBar indicating turbulent flow for 15 SLM an up. At 20 and 200 mBar the laminar flow limit is suggested by data to be even higher and reaching a value of 35 SLM. At 450 °C the data indicate a laminar flow up to 20 SLM at position 3A regardless of background pressure condition, except for 700 mBar where the data indicate a laminar flow at 35 and 40 SLM. 50 mBar strongly indicates a laminar flow profile up to a gas flow of 35 SLM. With a background pressure of 20 mBar, the data suggests a laminar flow profile up to at least 25 SLM. At 100 mBar the data indicates a laminar flow within the range of 30 SLM.