Two‐Photon Absorption by Envelope–Hole Coupled Exciton States in Cubic ZnSe. I. Energy Spectrum of the H_d Term and Valence‐Band Parameters

Abstract

I n the exciton spectrum of cubic ZnSe a fourfold energy splitting of the 2P exciton is observed by two-photon absorption. The distinct fine structure is the first experimental evidence for the coupling between the exciton envelope and the total hole spin. The energy spectrum of the spin Hamiltonian for Wannier excitons is calculated by use of a variational technique. Hydrogenic pand f-like trial functions are introduced as solutions, and the two equivalent Bohr radii are treated as independent variational parameters. First experimental data of the hole effective-mass parameters for the rs valence band are deduced from the observed energy splitting.Im Exzitonspektrum von kubischem ZnSe wird mit Hilfe der Zwei-Photonenabsorption eine vierfache Energieaufspaltung des 2P-Exzitons beobachtet. Die ausgepriigte Feinstruktur ist der erste experimentelle Beweis fur die Kopplung zwischen der Enveloppe des Exzitons und dem totalen Lochspin. Das Energiespektrum des Spin-Hamiltonoperators fur Wannier-Exzitonen wird mit einem Variationsverfahren berechnet. Als Losungsansatz werden wasserstoffartige p-und fFunktionen verwendet. Die beiden entsprechenden Bohrradien werden als unabhkngige Variationsparameter behandelt. Aus der beobachteten Energieaufspaltung ergeben sich erste experimentelle Daten der effektiven Lochmassenparameter fur das I',-Valenzband.

Excitonic effects on the two-color coherent control of interband transitions in bulk semiconductors

“…This is a good approximation for many typical semiconductors, including GaAs, since the electron-hole envelope function extends over many unit cells due to the screening of the Coulomb interaction by the static dielectric constant. 42,70,77,78,79 As a consequence of making the spherical approximation, the phase shifts and Coulomb enhancements we find in this paper are independent of crystal orientation.…”

Impurity Interaction on Excited Acceptor States in GaP

“…A possible 2S-2P mixing of the acceptor states via I€' has been estimated. However, this contribution is negligibly small over the total range of R. Presumably f-like admixtures to the unperturbed acceptor functions in (11) via HAd which range between 3 and 23% [7] may be responsible for the observed discrepancy. For D-A separations R < a D + aA the ansatz of (9) is no longer valid because [J*I has the same order of magnitude a s the energy difference between ground and first excited donor state.…”

“…They are derived by group-theoretical considerations similar to the results of [ll]. The term f F ( r A ) is the radial part of the p-like hydrogenic envelope as given in [7]. From (10) results a fourfold energy splitting of the 2P acceptor state [2] classified by the total angular momentum F of the hole ( F = 1/2, 3/2, 5/2(r,), 5/2(T',)).…”

Defects and Self-Compensation in Semiconductors

“…Such an alignment strongly favors n-type conductivity. Existing experimental data indicate that undoped ZnO can exhibit free electron concentrations as large as 1.1 × 10 21 cm −3 [68]. However, the extremely low position of the valence band edge indicates that it will be very difficult, if not impossible, to achieve any p-type doping of this material.…”