Surface chemistry in Atomic Layer Deposition of Gallium Nitride from Triethylgallium and Ammonia studied by mass spectroscopy

Gallium nitride (GaN) is a commonly used semiconductor owing to its high chemical and thermal stability, which makes it suitable for various applications in modern electronics. GaN film deposition is favored by atomic layer deposition (ALD) with triethylgallium (TEG) and ammonia (NH3) plasma as precursors. However, the surface reaction pathways of TEG under ALD conditions have not been experimentally evaluated. In this study, the surface chemistry of GaN films deposited on Si (100) during ALD with TEG and NH3 with and without plasma activation as precursors was investigated using mass spectrometry. The results suggest that the surface chemistry of the deposition process mainly consists of ethyl ligand elimination upon the TEG pulse, followed by ligand exchange during NH3 pulsing to form ethane (C2H6) as a reaction by-product on an NH2-terminated surface.