We have measured surface photovoltage (SPV), photoreflectance (PR), and photoluminescence (PL) spectra of two InAlAs/InxGa 1 - xAs/InAlAs metamorphic high-electron mobility transistor (MHEMT) structures. One possesses a V-shaped InxGa1 - xAs (x = 0.3-0.5-0.3) tensile-strained channel in In0.5Al0.5As/ InxGa1 - xAs/In0.5Al0.5As heterostructures, and the other is an In0.42Al0.58As/ In0.53Ga0.47As/In0.42Al0.58As MHEMT structures with InxGa1 - xAs (x = 0.53) compressively-strained channel grown on GaAs by molecular beam epitaxy. The comparison of SPV, PR, and PL spectra facilitates the identification of channel-well transitions in the MHEMT structures with different In xGa1 - xAs channels. Inter-subband transitions, Fermi-level energies, and built-in electric field of the two MHEMT structures with dissimilar InxGa1 - xAs channel are evaluated and discussed from the experimental analyses of SPV, PR and PL measurements. The results showed that the design of tensile-strained MHEMT structure enhances sheet-carrier density and avoids surface-roughness scattering by increasing V-shape electric field between the two channel interfaces. The electron mobility of the tensile-strained MHEMT structure is hence being promoted.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Metals and Alloys
- Materials Chemistry