TMAH Pretreatment to Minimize Ohmic Contact Resistance in InAlN/GaN-on-Si RF HEMTs

This is the authors' abstract. We don't add key points for this paper.

We report a novel tetramethylammonium hydroxide (TMAH) pretreatment to minimize the contact resistance(RC)using Ti-based Ohmic contacts to InAIN/GaN-on-Si RF HEMTs. The TMAH treatment is shown to etch the dislocation sites on the surface, which act as a medium for Ti diffusion into GaN during annealing. This enhances the TiN contact inclusion formation inside the GaN channel layer and results in anRCof0.23 ± 0.01 Ω-mm, which is threefold lower compared to a sample without TMAH treatment. The impact ofRCon RF performance is studied using sub-quarter micron HEMTs. For the sample with TMAH pretreatment, a highfTof 95 GHz and afT-LGproduct of19 GHz-μ mare achieved in a device with 200 nm gate and 900 nm source-to-drain separation.