В работе рассмотрены исследования управляемого многоуровневого переключения на основе сильного контраста оптических свойств для разных фаз некоторых халькогенидных материалов. Приведенные результаты позволяют создать полностью оптические волноводные и нейроморфные устройства и системы на их базе.

Методом лазерного синтеза из металлических мишеней при абляции излучением 248 и 532 нм получены тонкие пленки NbOx и TaOx в атмосфере кислорода и мемристоры на их основе в кроссбар-геометрии. В качестве электродов служили пленки Pt, Au, Ag, Ta, Nb. Изучено поведение ВАХ-мемристоров, полученных при разных условиях.

В работе представлены результаты исследования динамики управляемого изменения оптических свойств при лазерно-управляемом фазовом переходе в тонких пленках теллурида германия и соединения Ge-Sb-Te (225). Показано, что сильный контраст свойств разных фаз позволяет обеспечить стабильное многоуровневое переключение.

Тонкие пленки GeTe и GST подвергались импульсному лазерному воздействию наносекундной длительности, которое приводит к переходу между фазовыми состояниями материалов, что подтверждается рентгеновскими дифрактограммами и контролируется измерением электрической проводимости и отражательной способности образцов.

AbstractA series of thin films of Si_1 –_ x Mn_ x alloys with a thickness from 50 to 100 nm grown by pulsed laser deposition on an Al_2O_3 substrate in vacuum and in an argon atmosphere is investigated. The significant effect of the buffer-gas pressure in the sputtering chamber on the structural and magnetic homogeneity of the obtained films is shown. The conditions for the formation of a ferromagnetic phase with a high Curie temperature (>300 K) in the samples are studied. With the use of the Langmuir probe method, the threshold of ablation of a MnSi target by second harmonic radiation (λ = 532 nm) of a Nd:YAG Q -switch laser is determined. The time-of-flight curves for the plume ions are obtained with a change in the energy density at the target and argon pressure in the sputtering chamber. A nonmonotonic dependence of the probe time-of-flight signal amplitude on the argon pressure is established for high-energy particles of the plume.

The Langmuir-probe technique has been used to study the time-of-flight characteristics of a laser torch during MnSi-target ablation in vacuum and argon atmosphere by pulsed 532-nm laser radiation at 15-ns pulse duration. It is established that the amplitude of the signal of fast particles in the laser torch nonmonotonically depends on the buffer-gas pressure. Mechanisms determining this dependence of laser-torch characteristics on the pressure are considered. The influence of buffer-gas pressure on the ion-velocity distribution function is determined.

Abstract —The effect of laser pulse energy E on the possibility of forming of a homogeneous “high-temperature” ferromagnetic phase in Mn_ x Si_1 – _ x ( x ≈ 0.5) alloy films grown by pulsed laser deposition onto an Al_2O_3 (0001) substrate has been studied. The high-temperature phase with manganese concentration x ≈ 0.53 and the Curie temperature T _C ~ 200–300 K is shown to form near the substrate at the initial stage of the film growth. In this case, high values E ≥ 6.8 J/cm^2 favor the stabilization of this phase over all film thickness, while low values E = 2.6–5.7 J/cm^2 lead to a decrease in the manganese concentration in the upper film layer and the formation of additional “low–temperature” phase with T _C ≈ 30–50 K provided by silicides MnSi and Mn_4Si_7 crystallites.

AbstractThin Cd_ x Zn_1 – x O films with a Cd content in the range from zero to 35 at % are synthesized by pulsed laser deposition. A record-breaking solubility limit of 30 at % of Cd in wurtzite-structured Cd_ x Zn_1 – x O thin films is attained. Apart from the exciton peak, additional peaks associated with an inhomogeneous distribution of Cd in the samples are observed in the low-temperature (10 K) photoluminescence spectra of Cd_0.15Zn_0.85O and Cd_0.3Zn_0.7O films. An unsteady ( S -like) temperature dependence of the spectral position of the exciton photoluminescence peak in Cd_ x Zn_1 – x O films is observed. Such a dependence is associated with the effect of the localization of charge carriers.

Abstract—The effect of laser pulse energy E on the possibility of forming of a homogeneous “high-temperature” ferromagnetic phase in MnxSi1 – x (x ≈ 0.5) alloy films grown by pulsed laser deposition onto an Al2O3 (0001) substrate has been studied. The high-temperature phase with manganese concentration x ≈ 0.53 and the Curie temperature TC ~ 200–300 K is shown to form near the substrate at the initial stage of the film growth. In this case, high values E ≥ 6.8 J/cm2 favor the stabilization of this phase over all film thickness, while low values E = 2.6–5.7 J/cm2 lead to a decrease in the manganese concentration in the upper film layer and the formation of additional “low–temperature” phase with TC ≈ 30–50 K provided by silicides MnSi and Mn4Si7 crystallites.

AbstractThe Langmuir-probe technique has been used to study the time-of-flight characteristics of a laser torch during MnSi-target ablation in vacuum and argon atmosphere by pulsed 532-nm laser radiation at 15-ns pulse duration. It is established that the amplitude of the signal of fast particles in the laser torch nonmonotonically depends on the buffer-gas pressure. Mechanisms determining this dependence of laser-torch characteristics on the pressure are considered. The influence of buffer-gas pressure on the ion-velocity distribution function is determined.

Thin cadmium sulfide films grown by pulsed laser deposition on crystalline and amorphous substrates have been shown to consist of a mixture of a cubic (sphalerite structure) and a hexagonal (wurtzite structure) phase. We have demonstrated the possibility of controlling the percentages of the hexagonal and cubic phases in cadmium sulfide films by varying pulsed laser deposition parameters. Varying the deposition parameters allows one to control the optical and structural parameters and surface morphology of thin cadmium sulfide films.