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A practical computation method to find the eigenvalues and eigenspinors of quantum mechanical Hamiltonian is presented. The method is based on reduction of the eigenvalue equation to well known geometric algebra rotor equation and, therefore, allows to replace the usual det(H-E)=0 quantization condition by much simple vector norm preserving requirement. In order to show how it works in practice a number of examples are worked out in Cl_{3,0} (monolayer graphene and spin in the quantum well) and in Cl_{3,1} (two coupled two-level atoms and bilayer graphene) algebras., Comment: 12 pages, 3 figures in Advances in Applied Clifford Algebras, 2015

We present the results of time-resolved photoluminescence (TRPL) and optically detected microwave resonance (ODMR) spectroscopy investigations of semiconductor quantum dots and quantum wells. The ODMR spectra of InAs/GaAs QDs were detected via modulation of the total intensity of the QDs emission induced by 95 GHz microwave excitation and exciton fine structure was studied. Very long life times (up to 10 ns) of photoexcited carriers were observed in this system using TRPL at low temperatures and excitation intensities promising higher responsitivity of such QDs for quantum dot infrared photodetector development. The effects of proton and alpha particles irradiation on carrier dynamics were investigated on different InGaAs/GaAs, InAlAs/AlGaAs and GaAs/AlGaAs QD and QW systems. The obtained results demonstrated that carrier lifetimes in the QDs are much less affected by proton irradiation than that in QWs. A strong influence of irradiation on the PL intensity was observed in multiple QWs after high-energy alpha particles irradiation.

Multiple quantum well (MQW) samples grown by the molecular beam epitaxy method were irradiated by alpha particles from isotope 239.Pu. The photoluminescence (PL) spectra and PL integrated intensity dependencies are presented at various alpha particle fluences, up to 10(exp 11) cm(exp -2). The experimental results are in agreement with a model which assumes that point centers (residual impurities and point defects introduced during irradiation) are responsible for PL intensity decrease with the alpha particle fluence. It was found that annealing of irradiated MQW samples at a temperature above 650 K nearly restores the PL intensity. An enhancement of PL by more than an order of magnitude was observed at annealing temperatures higher than 850 K, just before GaAs and Al(0.35)Ga(0.65)As interdiffusion begins.

Undoped multiple quantum well (MQW) samples grown by the molecular beam epitaxy method were irradiated by 5.15 MeV energy alpha particles. A strong influence of irradiation on the photoluminescence (PL) intensity was observed in these nearly intrinsic samples: the PL intensity at liquid nitrogen and room temperatures decreased by more than two orders of magnitude at alpha particle fluence of 10(exp 11) cm(exp -2). The dependence of the PL intensity on irradiation dose is described by a rate equation model that takes into account the generation of nonradiative point centers in barriers and wells of the MQW structure during irradiation.

We present a detailed experimental study on photoluminescence quenching due to exciton and donor impact ionization by accelerated electrons under an in-plane nanosecond duration electric field created in $\mathrm{GaAs}/{\mathrm{Al}}_{0.35}{\mathrm{Ga}}_{0.65}\mathrm{As}$ quantum wells. From the photoluminescence transients measured by the time-correlated single-photon counting technique, we have determined the experimental conditions under which donor impact ionization can have an influence on quenching of the excitonic photoluminescence. The coefficient of two-dimensional exciton impact ionization has been estimated; its dependences on the applied electric field, lattice temperature, and width of the quantum wells are given.

Investigations of transient photoluminescence induced by external electric fields parallel to the layers of GaAs/Al0.35Ga0.65As quantum wells are reviewed. The photoluminescence was detected by time-correlated single-photon counting technique at liquid nitrogen and liquid helium temperatures applying electric fields of nanosecond duration to the wells of different width. It is shown how experimentally one can resolve between excitonic and donor impact ionization processes in combining spectral and time domains. From the study of the spectral-temporal dynamics at initial moments we have determined the coefficient of exciton impact ionization as a function of electric field for various widths of the quantum wells.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The luminescence induced by alpha particles in GaAs/Al0.35Ga0.65As multiple quantum well (MQW) semiconductor was detected and investigated. The luminescence was observed at liquid nitrogen and at room temperatures as light flashes induced by individual (alpha) -particles. The MQW samples studied, in addition, were investigated using standard photoluminescence method to show that (alpha) - particle created flashes are associated with a radiative decay of 2D excitons in quantum wells. Since the number of detected light quanta in a flash is critical, a discussion of the collection efficiency of photons created by a single (alpha) -particle is presented.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.