Inverse parabolic quantum wells grown by molecular-beam epitaxy using digital and analog techniques

Abstract

An A1036Gao 64As/Al Ga& As inverse parabolic quantum-well structure was grown by molecularbeam epitaxy using both digital and analog compositional grading techniques. Photoluminescence and photocurrent measurements showed distinct exciton peaks for both types of wells. A large Stark shift was found for the digital well, in agreement with the calculations. An observed deviation for the analog well was ascribed to Auctuation in quantum-well parameters. Finally, advantages and disadvantages of the two growth techniques are discussed.

Binding energy of hydrogenic impurity states in an inverse parabolic quantum well under static external fields

“…z e is the position of the electron along the z-axis, z i is the position of the impurity along the z-axis and V (z e ) is the confinement potential profile for the electron in the z-direction. The confinement potential has the form [15,17] …”

“…Apart from the well-known and well-studied quantum well hetero-structures (QWHs), which have square [3,6] and parabolic [3,[7][8][9][10] potential shape, cases of QWHs with half parabolic [11], graded [12], V-shaped [13] and inverse parabolic quantum well (IPQW) potential shape [14][15][16][17][18][19] have been produced and studied.…”

“…In addition, their influence can be controlled by the presence of external fields. Several articles have been published on the influence of external static (electric and magnetic) fields on hydrogenic impurities [10][11][12][13][17][18][19][29][30][31][32][33][34][35].…”

“…This originates from the quicker decrease in the overlap of the electron and heavy hole wave functions with the applied electric field. Actually this feature is much desirable for the quantum-confined field-effect light emitter and in the study of the confined Stark effect [15]. Although IPQW presents large interest, the existing literature on its fundamental physical properties is very limited [14][15][16][17][18][19].…”

Gain-maximized GaAs/AlGaAs quantum-cascade laser with digitally graded active region

“…Since the layers in the DG section are not confinement layers, but rather act via the average composition, with wave functions evenly penetrating the well and barrier slices, the width fluctuations should average out, with no significant effect on the wave function shapes. There is experimental evidence 31 that despite the increased number of interfaces the exitonic lines in such DG structures are not much broader than in simple rectangular QWs, so one may expect limited broadening of intersubband lines as well.…”