Device quality In0.29Al0.71 As and In0.3Ga0.7 As epilayers have been successfully grown on GaAs substrates using a carefully designed InxAl1–xAs multistage strain-relaxed buffer. Cross-sectional transmission electron microscopy has shown that the misfit dislocations are confined in the lower regions of the metamorphic buffer layer. The Hall electron mobility of the modulation doped structure grown on the InAlAs buffer was 6160 and 25379 cm2/V･s with sheet carrier densities of 1.9 × 1012 and 1.8 × 1012 cm–2 at 300 and 77 K, respectively. The excellent characteristics of the field-effect transistors fabricated on this structure have indicated its potential for practical applications.
- High electron mobility transistor
- Lattice mismatch