Electron transport in AlGaN/GaN HEMTs using a strain model

The electron transport in AlGaN/GaN HEMTs was investigated using the strain model by Sentaurus TCAD simulations. The impact of strain variations on electron transport properties was studied. The adjustment of strain is achieved by changing strained lattice constant (a) and the strain relaxation (R) in AlGaN layer based on strain model, and then the relationship between piezoelectric polarization and strain values is discussed. The results show that an external tensile strain in AlGaN layer has a strong influence on the distribution and concentration of 2DEG located close to the AlGaN/GaN interface. Meanwhile the threshold voltage and saturated drain current are proportional to the strain values, and the breakdown voltage is improved due to the adjustment of strain. Furthermore, the change of electron transport was also investigated by decreasing the local strain near the gate edge in AlGaN layer. It can be founded that the surface electric field becomes more uniform and the breakdown voltage is enhanced. The results based on the relation between strain and electron transport are beneficial to regulate the electrical properties in AlGaN/GaN HEMTs.