Saddle Points and Stark Ladders: Exact Calculations of Exciton Spectra in Superlattices
نویسنده
چکیده
A new, exact method for calculating excitonic absorption in superlattices is described. It is used to obtain high resolution spectra showing the saddle point exciton feature near the top of the miniband. The evolution of this feature is followed through a series of structures with increasing miniband width. The Stark ladder of peaks produced by an axial electric field is investigated, and it is shown that for weak fields the line shapes are strongly modified by coupling to continuum states, taking the form of Fano resonances. The calculated spectra, when suitably broadened, are found to be in good agreement with experimental results. 78.66.Fd, 71.35.+z, 78.20.Jq Typeset using REVTEX
منابع مشابه
Electroabsorption spectroscopy of effective-mass AlxGa12xAs/GaAs Fibonacci superlattices
Effective-mass Fibonacci superlattices are composed of quasiperiodic sequences of weakly coupled quantum wells in which the transfer-matrix element is significantly smaller than the confinement energy, which is significantly smaller than the confining potential. We identify several distinct classes of quasiperiodic superlattices that are distinguished by diagonal vs off-diagonal quasiperiodicit...
متن کاملRigorous excitonic theory of field dependent superlattice absorption
We have performed calculations of the field dependent excitonic absorption spectra of semiconductor superlattices in a model which is capable of fully taking into account the Coulomb interaction and both bound and continuum excitonic states. Results are obtained for the complete range of fields from the Franz-Keldysh to the Wannier-Stark regime. The lineshapes of the excitonic spectra are shown...
متن کاملResonance wave functions located at the Stark saddle point
We calculate quantum-mechanically exact wave functions of resonances in spectra of the hydrogen atom in crossed external fields and prove the existence of long-lived decaying quantum states localized at the Stark saddle point. A spectrum of ground and excited states reproducing the nodal patterns expected from simple quadratic and cubic expansions of the potential in the vicinity of the saddle ...
متن کاملSADDLE POINT VARIATIONAL METHOD FOR DIRAC CONFINEMENT
A saddle point variational (SPV ) method was applied to the Dirac equation as an example of a fully relativistic equation with both negative and positive energy solutions. The effect of the negative energy states was mitigated by maximizing the energy with respect to a relevant parameter while at the same time minimizing it with respect to another parameter in the wave function. The Cornell pot...
متن کامل7 M ay 1 99 7 Lateral superlattices as voltage - controlled traps for excitons
We demonstrate the localisation of quantum well excitons in a periodic array of linear traps using photoluminescence experiments. The excitonic traps are induced by applying spatially alternating external voltages via interdigitated metal gates. The localisation originates from the periodical modulation of the strength of the quantum-confined Stark effect in the plane of the quantum well. In ou...
متن کامل