Comparison of characteristics of AlGaN channel HEMTs formed on SiC and sapphire substrates

The fundamental device characteristics of AlGaN channel high electron mobility transistors formed on 4H-SiC and sapphire substrates are compared, and it is found that the drivability is apparently better for the SiC substrate. Judging from the simultaneous enhancement in mobility and the carrier concentration of the two-dimensional electron gases for the SiC substrate, the advantages of the SiC substrate originate from the excellent crystal quality of the AlGaN channel layer including the interface with the AlGaN barrier layer, which should be due to less lattice mismatch with the substrate.