Electron effective mass and nonparabolicity in InGaAs/InAlAs quantum wells lattice-matched to InP

Nonparabolic electron effective masses in InGaAs quantum wells (QWs), sandwiched by thick InAlAs barriers of 0.52-eV band offset, were studied in normal and parallel directions to the QW plane. The Normal mass was experimentally obtained by observing interband photocurrent spectra of undoped InGaAs multi-QW structures. The mass increased by more than 50% from the bulk band edge mass, 0.041m0. Electron eigenenergies were calculated in QWs based on Kaneʹs three-level band theory. The calculated ‘apparent’ normal mass as a function of kinetic energy up to 0.5 eV agreed well with experiments. The parallel mass in n-type modulation-doped InGaAs QWs was experimentally obtained by pulse cyclotron resonance up to 100 T. The analysis in quantizing magnetic fields, modified for two-dimensional QWs, fits well with cyclotron energy. The ‘apparent’ parallel mass as a function of energy was obtained consistently.