Ultralow RF Loss for Si-Based GaN Materials with a Variable Power Phosphorus Ion Implantation Method

In this work, the source of the radio frequency loss in GaN-on-Si materials is investigated in detail. Through measuring S parameters and capacitor voltage characters of samples with different reactive ion etching depths, it is revealed that the radio frequency loss derives from the p-type parasitic channel at the Si interface induced by the diffusion aluminum atom. Based on this viewpoint, the donor phosphorus compensation method was proposed to compensate the p-type parasitic channel of the diffusion Al atom. The approximately linear distribution state of the in situ aluminum diffusion and the normal distribution state ex situ phosphorus ion implantation is revealed according to secondary ion mass spectroscopy and transport of ions in matter (TRIM) simulation methods. Moreover, the variable power phosphorus ion implantation is employed to finely compensate the parasitic channel. As a result, an ultralow coplanar waveguide RF loss of 0.4 dB/mm at 40 GHz is obtained with 600 nm metal thickness. The results in this work have an instructive significance for the application of GaN-on-Si in the future.