The role of photoluminescence excitation spectroscopy in investigation of quantum cascade lasers properties

The properties of quantum cascade laser (QCL) structures have been investigated by optical technique based on spontaneous emission measurements: photoluminescence excitation (PLE) spectroscopy. Three types of test structures used for obtaining final QCL device were examined , i.e., single sequence of coupled quantum wells, which form an active region of the device, 30 sequences of this active region separated by 25 nm thick AlGaAs barriers and finally complete, undoped structure consisting of 30 of sequences repeated active regions and superlattice injectors. The results has been compared with numerical simulations. The role of such measurements has also been discussed

The influence of MBE growth conditions on optical properties of InGlGaAs/AlGaAs structures

Optical properties of compressively strained In₀.₂₄Al₀.₁₉Ga₀.₅₇As layers were investigated as a function of the MBE growth conditions. The optimum temperature of the crystal surface (Ts) for MBE growth of this quaternary layer as well as the optimal cooling down process necessary for achieving appropriate Ts for InAlGaAs were experimentally found

The Effect of Atomic Layer Deposition of ZrO2 on the Physicochemical Properties of Cobalt based Alloys Intended for Prosthetic Dentistry

The paper presents the effect of ZrO2 layer deposition by the ALD process on the physicochemical properties of cobalt-based alloys (Realloy C and EOS CoCr SP2) intended for application in prosthetic dentistry. The paper shows the results of the surface roughness measurements made by the AFM method as well as the wettability and free surface energy measurements. Additionally, potentiodynamic tests of pitting corrosion resistance and electrochemical impedance spectroscopy in a solution of artificial saliva were carried out. Tests were carried out on the samples in the initial state and after surface modification with the ZrO2 layer. Based on these results, the usefulness (e.g. enhancement of corrosion resistance and biocompatibility) of the proposed ZrO2 layer on the cobalt alloys was assessed

Oval defects in crystals grown by MBE technique: study and methods of elimination abstract

The paper is devoted to a group of macroscopic defects which may be found in epitaxial A3 B5 materials grown by MBE technique. Morphology, geometry and optical properties of defects were studied by means of several experimental methods. The experimental data have been compared with the information taken from literature concerning sources of the defects and causes of their appearance

The Study of Thermal Properties of GaAs/AlGaAs Quantum Cascade Lasers

Temperature change in quantum cascade laser can be estimated by studying the device resistance change. Using this method we compared quantum cascade laser structure mounted on diamond heat spreader and without heat spreader. We have shown that the use of heat spreader reduces temperature increase even by 40%