Driven by the increasing demand for 5G communication, GaN radio frequency (RF) device on Si technology has been flourishing attributable to the large size, low cost, and compatibility with complementary metal–oxide–semiconductor technology. However, a significant challenge is that a high-conductance parasitic channel forms at the interface between the III-N epitaxial layers and the Si substrate, leading to severe RF loss, which has been considerably impairing both the performance and advancement of RF GaN-on-Si technologies. Despite continuing controversies concerning the physical mechanisms engendering the parasitic channel, clarification is critically needed. Standing apart from traditional studies on RF loss in III-N epilayers grown on Si, this article comprehensively investigates the bonding interface of GaN thin film and Si(100) substrate realized via direct surface activated bonding and ion-cutting technologies. It was clearly determined that substantial diffusion of gallium (Ga) atoms into the Si substrate at the bonding interface occurred even at an annealing temperature as low as 350 °C. Subsequent high-temperature post-annealing at 800 °C intensified this diffusion, activating Ga atoms to form a p-type highly conductive parasitic channel. Simultaneously, it triggered Ga atoms aggregation and incited melt-back etching within the Si substrate at the interface. Contrasting with the conventional hetero-epitaxy, this study presents a compelling view based on the bonding technique. It conclusively elucidates the physical mechanisms of the formation of the primary source of RF loss—the p-type highly conductive parasitic channel.

中文翻译：

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阐明无缓冲 GaN/Si 异质键合结构寄生沟道的形成机制

在5G通信需求不断增长的推动下，基于硅技术的GaN射频(RF)器件因其尺寸大、成本低以及与互补金属氧化物半导体技术的兼容性而蓬勃发展。然而，一个重大挑战是，III-N 外延层和 Si 衬底之间的界面处会形成高电导寄生沟道，导致严重的 RF 损耗，这极大地损害了 RF GaN-on 的性能和进步。 -硅技术。尽管关于产生寄生通道的物理机制仍然存在争议，但迫切需要澄清。与传统的 Si 上生长的 III-N 外延层射频损耗研究不同，本文全面研究了通过直接表面激活键合和离子切割技术实现的 GaN 薄膜与 Si(100) 衬底的键合界面。可以清楚地确定，即使在低至 350 °C 的退火温度下，镓 (Ga) 原子也会在键合界面处大量扩散到 Si 衬底中。随后的 800 °C 高温后退火强化了这种扩散，激活 Ga 原子形成 p 型高导电寄生沟道。同时，它引发了 Ga 原子聚集并引发了界面处 Si 衬底内的回熔蚀刻。与传统的异质外延相比，这项研究提出了基于键合技术的令人信服的观点。它最终阐明了射频损耗主要来源——p 型高导电寄生通道形成的物理机制。