Influence of a thick nitride layer on transmission loss in GaN-on-3C-SiC/low resistivity Si

Abstract

We report the effect of a thick nitride layer on transmission loss in GaN-on-3C-SiC/low resistivity Si (LR-Si). Microstrip lines of finite length and width with ground pads were fabricated on three GaN-on-3C-SiC/LR-Si epitaxial structures with varying nitride layer thicknesses of 3.2, 5.3, and 8.0 𝜇m. The loss performance of microstrip lines on different substrates was evaluated in the frequency range of 0.1 to 9 GHz. The sample with 8.0 𝜇m thick nitride layer showed a minimal loss of 0.3 dB/mm at 9 GHz compared to the other samples. The evaluated data from electromagnetic (EM) simulation also confirmed a decreasing trend of loss with increasing nitride layer thickness. Temperature dependent loss evaluation also verified the above fact.

AlGaN/GaN HEMT on 3C-SiC/Low-Resistivity Si Substrate for Microwave Applications

“…The GaN-on-Si devices, as above-mentioned, face the problem of the low resistivity of Si substrates when we use them in a microwave frequency due to a high parasitic capacitance which lead to RF leakage [9], [14]. In this regard, a thick nitride layer can be an excellent solution to curb the parasitic effect that generates from the low resistivity of the Si substrate [14], [15]. In a previously reported work, a 9 μm thick buffer layer was achieved on Si using 7 μm strained layer superlattice (SLS) structure [16].…”