Analysis of AlGaN/GaN epi-material on resistive Si(111) substrate for MMIC applications in millimeter wave range

This paper reports RF losses and buffer isolation analysis of AlGaN/GaN epitaxial layers grown on high resistive Si(111) substrate with different GaN buffer thicknesses. Measurements are performed at different temperatures. At 85°C, measurements exhibit very low isolation current down to 80 nA/mm between two ohmic contacts biased at 180 V and separated by 10 µm. At 100°C, coplanar lines show RF losses around 0.4 dB/mm at 50 GHz. No drastic degradation of substrate quality and buffer isolation appeared with the temperature increase. This study shows the potentiality of AlGaN/GaN on resistive Si(111) for the fabrication of low cost Monolithic Microwave Integrated Circuits (MMICs) working in millimeter wave range.