Effect of GaN Cap Thickness on the DC Performance of AlGaN/GaN HEMTs

We prepared AlGaN/GaN high electron mobility transistors (HEMTs) with GaN cap thicknesses of 0, 1, 3, and 5 nm and compared the material characteristics and device performances. It was found that the surface morphology of the epitaxial layer was effectively improved after the introduction of the GaN cap layer. With the increase of the GaN cap thickness, the carrier concentration (n