BAND OFFSET DETERMINATION IN ANALOG GRADED PARABOLIC AND TRIANGULAR QUANTUM-WELLS OF GAAS/ALGAAS AND GAINAS/ALINAS

The band offset parameter Q(c) = DELTA-E(c)/DELTA-E(g) for both GaAs/AlGaAs (lattice matched to GaAs), and GaInAs/AlInAs (lattice matched to InP) was extracted from the optical interband transition energies obtained from both triangular and parabolic quantum well shapes of various widths. The wells were grown using continuous analog compositional grading as opposed to the discrete, superlattice (digital) grading used by previous researchers. Electron beam electroreflectance (EBER) was the primary technique used to measure the interband transition energies. By combining the theoretical energies from quantum mechanical potential well calculations with EBER measured energies, it was possible to extract band offset values in a self-consistent manner. Q(c) values obtained were 0.658 +/- 0.009 and 0.650 +/- 0.001 for GaAs/AlGaAs and GaInAs/AlInAs, respectively. Measurements also revealed that Q(c) was both temperature and concentration independent within the range of composition studied.