InP-based InAlAs/InxGa1-xAs/InP high-electron-mobility transistors (HEMTs) with a symmetrically graded channel (SGC-HEMT) and an inversely graded channel (IGC-HEMT) were fabricated and studied. The SGC-HEMT exhibits better Hall, dc and RF characteristics than the IGC-HEMT because there are more electrons accumulated in the symmetrically graded channel. However, the IGC-HEMT has better thermal stability than the SGC-HEMT because the former has higher bandgap discontinuity at the channel/buffer heterojunction and less Coulomb scattering from a δ-doped layer. Furthermore, the IGC-HEMT sustains larger output power than the SGC-HEMT attributed to better breakdown characteristics. Therefore, HEMTs with the symmetrically graded and an inversely graded channel are suitable for high-speed and high-power applications, respectively.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering
- Materials Chemistry