The Influence of AlN Nucleation Layer on Radio Frequency Transmission Loss of AlN‐on‐Si Heterostructure

• Published in: Physica status solidi. A, Applications and materials science Vol. 217; no. 7
• Main Authors: Chang, Shane, Zhao, Ming, Spampinato, Valentina, Franquet, Alexis, Do, Thi-Hien, Uedono, Akira, Luong, Tien Tung, Wang, Tsang-Hsuan, Chang, Li
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.04.2020
• Subjects: AlN nucleation layers; Aluminum nitride; coplanar waveguides; Crystal structure; Crystallinity; Epitaxial growth; Gallium nitrides; GaN on Si; Heterostructures; high frequency; Metalorganic chemical vapor deposition; Nucleation; Radio frequency; radio frequency loss; Silicon; Thermal diffusion; Transmission loss
• ISSN: 1862-6300; 1862-6319
• DOI: 10.1002/pssa.201900755

Reducing radio frequency (RF) transmission loss is a key requirement when fabricating GaN‐on‐Si RF devices. To get a better insight into the RF loss mechanism in the GaN‐on‐Si structure, the RF loss of an AlN/Si template is investigated by varying the growth temperature of AlN during a metalorganic chemical vapor deposition process. The results show that the RF loss of the AlN/Si template is dominated by the interface loss due to the p‐type conductive channel at the AlN/Si interface, which is induced by the thermal diffusion of Al during the high‐temperature growth. Although a low growth temperature of the AlN nucleation layer can suppress the RF loss in the AlN/Si template, it results in a low crystalline quality of AlN for practical use. Optimizing the growth temperature of the AlN nucleation layer is essential to obtain a good balance between the crystalline quality, morphological quality, and RF loss such that the AlN/Si template is suitable for epitaxial growth of the complete GaN‐on‐Si RF device structure. Radio frequency (RF) loss of an AlN‐on‐Si template is shown to be dominated by the interface loss due to the p‐type conductive channel at the AlN/Si interface resulting from thermal diffusion of Al into the Si substrate during high‐temperature growth. A good balance among crystalline quality, smooth surface morphology, and RF loss is required for the AlN/Si template to obtain a high‐performance GaN‐on‐Si RF device structure.