Material and device issues of InAlN/GaN heterostructures

Motivation for replacing the AlGaN barrier layer of the conventional AlGaN/GaN HEMTs with lattice-matched InAlN is explained. State-of-the-art InAlN/GaN HEMTs are reviewed; emphasize is given to the analysis of the normally-off InAlN/GaN HEMTs using either a gate recessing or a concept of polarization engineering. Reliability issues of InAlN/GaN HEMTs are studied for different stress conditions and results discussed in respect to AlGaN/GaN HEMTs. Concept of InAlN/GaN/AlGaN double-heterostructure QW HEMT is shown to be more effective in blocking the hot electron injection in to the buffer. Novel InN-channel based devices are suggested with a relaxed InAlN buffer. The InN/InAlN-based HEMTs should be the choice for reaching a THz frequency range.