Variations of the hole effective masses induced by tensile strain inIn1−xGa

Abstract

Magneto-optical experiments have been used to study a range of InoaAsP-based multiple-quantumwell (MQW) structures containing biaxial strains, ranging from 1.6% tensile to 1.0% compressive. The observed excitonic transitions, involving both heavy and light holes, are studied in fields up to 15 T. Estimates of the hole effective masses are made, providing details of the valence-band nonparabolicities, and electronlike behavior is demonstrated for both heavy and light holes with different amounts of tensile strain. This is related to band crossings within the valence band and enables an estimate of 0.68+0. 10 to be made of the heterojunction band offset in a strained In, "Ga"AsilnGaAsP MQW, with approximately 1.25%%uo tensile strain in the well region. The experimental data are compared to the results of k. p Hamiltonian calculations of the in-plane valence-band dispersion.

Investigation of band non-parabolicities in strain-balanced GaInAs/GaAlInAs coupled quantum wells

“…This occurs for a comparatively lower strain in M1011 due to the increased quantum-well thickness. Similar marked changes in the hole masses have been demonstrated near the crossing of HH1 and LH2 levels in tensile-strained InGaAs/InGaAsP MQWs [3].…”

“…A coincidence of the light-and heavy-hole exciton energies will have a considerable effect on the optical properties and has been proposed for polarization-independent modulators [1,2]. Changes to the energy separation of the light-and heavy-hole states modifies their character and coupling, and large changes in effective mass can result as reported for InGaAs/InGaAsP MQWs [3]. This paper describes measurements on a series of 20-period MQW structures grown by MBE on n + -InP substrates with the compressive strain in the thin (20-30Å) Ga x Al y In 1−x−y As barriers selected to balance the tensile strain in the Ga x In 1−x As wells.…”

“…Material parameters extracted from these calculations are employed in calculations of the Landau-level energies using a three-dimensional hydrogenic model for the exciton [5]. Conduction band non-parabolicity is taken into account using a k·p expression to compute the increase in the strained band-edge electron masses resulting from electric and magnetic quantization [3]. The exciton binding energies and inplane hole mass (m * hh ) are used as fitting parameters, with calculated transition energies shown in Figs.…”

Optical investigation of strain-balanced superlattices

“…This is due to the tensile strain-induced coupling of the lh1 energy level to the nearby hh1 and hh2 levels. The above calculations show that the hh2 level is only 11 meV below the lh1 level and the difference in parity of these states results in an even stronger coupling than for the hh1-lh1 interaction [5,9]. Martin et al [5] show the results of Luttinger-Kohn Hamiltonian calculations of the in-plane dispersion relations for the hh1, lh1 and hh2 levels for an InGaAs quantum-well structure very similar to our own.…”

“…For example, polarization insensitive modulators can be achieved using a small degree of tensile strain in an InGaAs layer to bring the first heavy and light hole levels close to degeneracy. To enable accurate device design, much work has been done [1][2][3][4][5] to characterize the effects of strain on the material parameters (carrier effective masses, mobility, band offsets, etc.) which control the ultimate transport and optoelectronic properties.…”