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We examine the properties of the quantum Lorentz group SO q(3, 1) using the [Formula: see text] matrix given in Ref. 14. We show that this matrix together with the q-deformed metric C provide a representation of a BWM algebra. Using the projection operators which decompose the [Formula: see text] matrix into irreducible components, we give the general definition of the corresponding quantum space, i.e. the q-deformed Minkowski space and the q-deformed Clifford algebra. We also construct the q analog of Dirac matrices and show that they form a matrix representation of the q-deformed Clifford algebra.

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The interdiffusion in single quantum well structures was studied for a variety of II -VI semiconductor materials based on CdTe and ZnSe. In particular we have investigated CdTejCdMnTe, CdTejCdMgTe, HgxCdt_xTejHg y Cd t _ y Te and ZnSejCdZnSe structures in which an intermixing of column II elements can be induced as well as ZnSejZnSSe allowing an interdiffusion within the column VI sublattice. The diffusion was induced by rapid thermal annealing (RTA) for 1 min at different temperatures. The resulting blue shift of the characteristic emission spectrum was analyzed using photoluminescence spectroscopy. We observed a significant differencc of thc diffusion behavior between both groups of materials. While in all three CdTe based material systems an almost complete intcrdiffusion within the column II sublattice could be obtained at a high optical quality of the structures, both ZnSe based quantum wells show only remarkably small diffusion lengths. For all three CdTe based quantum wells we derived an activation energy of the interdiffusion process from a simple Fickian diffusion model applied to our measurements. We obtained a value of 2.8 eV for CdTejCdMnTe and CdTejCdMgTe and a value 2.1 eV for HgxCdt_xTejHgyCdl_yTe.Due to the fundamental role of diffusion for the production of semiconductor devices, the study of diffusion in semiconductor crystals has been of large interest in the last years. Self-diffusion or impurity diffusion in 111-V and 11-VI bulk materials was studied, e.g. by secondary ion mass spectroscopy (SIMS), a technique that allows a direct scanning of the diffusion profile [1]. In recent years, diffusion has also been investigated in thin heterostructures which offer an * Corresponding author.interesting source of concentration gradients. The interdiffusion of the materials in the well and barrier layers results in a blue shift of the emission spectrum [2]. The technological interest on this effect arises from the possibility to tune the wavelength of an optical emitter by simply annealing the device. On the other hand, it has been shown in III -V quantum .wells that the selective implantation of ions in a semiconductor heterostructure offers the possibility to define a lateral confinement [3,4]. Up to now the investigation of diffusion in heterostructures has been restricted mainly to 111-V materials. Only few 0022-0248/94/$07.00