The crystallization of as‐grown amorphous Hf 0.5 Zr 0.5 O 2 (HZO) thin films to the metastable ferroelectric phase by pulsed laser annealing (PLA) is investigated. PLA experiments are conducted using a Nd:YAG laser operating in two regimes: Q ‐switched mode with a pulse duration of τ ≈ 16 ns and free‐running mode ( τ ≈ 1 ms). The crystallization of a ferroelectric orthorhombic phase in the annealed films is confirmed by X‐ray diffraction, polarization versus electric field ( P–E ) measurements, and piezoresponse force microscopy (PFM) analyses. Remnant polarization up to 2 P r ≈ 50 μC cm −2 is achieved in the TiN/HZO/W capacitor structures grown on the Si substrate and subjected to millisecond PLA. In contrast, the use of laser annealing in a 10 ns pulse duration range is found ineffective for the crystallization of any HZO phase in capacitor structures. Detailed PFM analysis across a capacitor device area reveals the effect of the local temperature on the sample surface during PLA on the resulting ferroelectric domain structure. The lower thermal impact on the substrate during PLA opens the possibility of creating local areas of the ferroelectric phase in HZO films using reflecting copper masks.

Проведено численное моделирование процессов нагрева, плавления и кристаллизации твердого раствора SiGe на кремниевой подложке, происходящих под действием наносекундного лазерного излучения, и проанализирован механизм формирования ячеистых структур из-за сегрегационного разделения элементов на стадии отвердевания бинарного расплава. Результаты вычислений сопоставлены с известными экспериментальными данными, характеризующими продолжительность лазерно-индуцированных фазовых превращений и средний размер ячеек (образующихся вследствие эффекта концентрационного переохлаждения) в зависимости от плотности энергии в лазерном импульсе.

The photothermoacoustic method has been used for diagnostics of thermobarodynamic processes in the metal In(400 nm)/semiconductor (CdTe) thin-film system under nanosecond laser irradiation (7 ns, λ = 532 nm) in natural conditions (in air) and in a liquid medium (water). From the analysis of the data obtained, the dependence of the pressure induced in the energy-release region on the irradiation energy density has been established and the melting threshold of In film has been determined. Under irradiation of In/CdTe in water, the pressure is higher than in air: 17 times higher at the melting threshold of In film and 30 times higher at twice the temperature. It has been found that the laser pulse treatment of In/CdTe/Au samples in water makes it possible to obtain diode structures with better parameters: smaller leak currents and a steeper current-voltage characteristic under the forward bias of the p - n junction.

Heating, melting, and crystallization processes of SiGe solid solution on a silicon substrate occurring under the influence of nanosecond laser irradiation were numerically simulated. Formation of cellular structures during solidification of the binary melt due to a segregation element separation was analyzed. Calculation results were compared with known experimental data characterizing the duration of laser-induced phase transformations and average sizes of the cells (which are formed due to the effect of concentration supercooling) as a function of the power density in the laser pulse.

Фототермоакустическим методом проведена диагностика термобародинамических процессов, происходящих при наносекундном лазерном облучении (7 ns, λ = 532 nm) в естественных условиях (на воздухе) и в жидкой среде (вода), тонкопленочной системы металл In(400 nm)−полупроводник CdTe. На основе анализа полученных данных установлена зависимость давления, возникающего в области энерговыделения, от плотности энергии облучения системы и определен порог плавления плeнки In. При облучении In/CdTe в воде давление больше, чем на воздухе — в 17 раз на пороге плавления плeнки In и в 30 раз при его двухкратном превышении. Выяснено, что импульсная лазерная обработка образцов In/CdTe/Au в воде позволяет получать диодные структуры с лучшими параметрами — меньшими токами утечки и более крутой вольтамперной характеристикой при прямом смещении p−n-перехода.

The dynamics of the reflectivity at λ = 0.53 μm and the IR radiation of silicon in the wavelength range 0.9–1.2 μm is studied under the action of nanosecond ruby laser radiation pulses. When radiation energy density W is lower than the threshold of laser-induced melting of the surface of a semiconductor crystal, the major contribution to the IR radiation emitted by this crystal is made by edge photoluminescence. As the melting threshold is exceeded, the nanosecond dynamics of the detected IR radiation changes from photoluminescence to the thermal radiation of the forming Si phase melt with a high reflectivity. The results of pyrometric measurements of the peak melt surface temperature as a function of W obtained at an effective wavelength λ e = 1.04 μm of the detected IR radiation agree with the data of analogous measurements performed at λ e = 0.53 and 0.86 μm.

The kinetics of phase transformations of nanocrystals in a crystal matrix is considered upon non-stationary heating by laser pulses. The melting and crystallization kinetics of nanocrystals is described taking into account their size, shape, elemental composition, and elastic deformations appearing due to the mismatch of the lattice constants for nanocrystals and the matrix. The possibility of decreasing the dispersion of nanocrystals over their size in heterostructures with quantum dots is predicted. As an example, melting of Ge nanocrystals in a Si matrix is considered.

Рассмотрена кинетика фазовых превращений нанокристаллов в кристаллической матрице в нестационарных условиях нагрева при импульсном лазерном воздействии. Описана кинетика плавления и кристаллизации нанокристаллов с учетом их размеров, формы, элементного состава, а также упругих деформаций, возникающих вследствие различия постоянных решеток нанокристаллов и матрицы. Предсказана возможность уменьшения дисперсии нанокристаллов по размерам в гетероструктурах с квантовыми точками. В качестве примера рассмотрено плавление нанокристаллов Ge в Si-матрице

The method for the formation of silicon nanoparticles by picosecond laser pulses is studied upon the surface irradiation of the single-crystal silicon in various liquids. The ablation products are investigated using the atomic-force microscopy and Raman spectroscopy. The experimental results indicate the crystal-line structure of nanoparticles and the dependence of their size on the ablation medium.

The results of an investigation of the temperature dynamics of certain metals, measured by a photoemission method with a time resolution of 1 μsec, when they are heated in air and in an argon medium by millisecond laser radiation (λ = 1.06 μm) with energy densities of 75–140 J/cm2 are presented.

In this work buried nanocrystalline CrSi2 layers were synthesized by ion implantation, pulsed annealing and MBE. The structural, optical and thermoelectrical properties of CrSi2 layers were studied by methods of SEM, TEM, RBS, PL and Seebeck coefficient measurements. The characteristic features of pulsed nanosecond annealing of Cr-implanted Si and epitaxial growth of triple Si/nc–CrSi2/Si heterostructures were established. It is shown that grown Si/nc–CrSi2/Si heterostructures, which preliminary implanted with the high-dose (ϕ=6×1016cm−2) of Cr+ ions, have the noticeable low temperature (T=10–100K) photoluminescence signal at 1450–1600 nm and the large Seebeck coefficient (−(60–300) μV/K) in the temperature range of T=340–415K.

Представлены результаты исследования динамики температуры некоторых металлов, измеренной фотоэмиссионным методом с временным разрешением 1 мкс, при их нагреве в воздухе и среде аргона миллисекундным лазерным излучением (λ=1,06 мкм) с плотностями энергии 75-140 Дж/см2.The results of temperature dynamics study for certain metals measured by photoemission method with temporal resolution 1 mks at heating in air and argon medium by millisecond laser radiation (λ = 1,06 mkm) with energy densities 75 - 140 J/cm2 are presented.

The dynamics of phase transitions induced by nanopulsed ruby laser radiation (80 nsec, 2 J/cm2) both in silicon layers doped with erbium ions and in those containing doped erbium and oxygen have been studied by an optical probing method. It is shown that the reflectivity behavior of structures under pulsed irradiation is governed by phase transitions (melting and crystallization) of implanted silicon and also by interference effects at the interfaces of the resulting phases. It is established that the profiles of erbium distribution change under nanosecond laser irradiation and that the dopant is forced out to the surface due to a segregation effect at small implantation doses. As the implanatation dose increases, diffusion deep into the sample tends to prevail over segregation. A considerable increase in the photoluminescence peak intensity at 0.81 eV is found after both the pulsed laser processing and thermal post-annealing of doped samples as opposed to spectra of samples subjected either to thermal annealing or to pulsed laser irradiation.

SiGe/Ge layers were deposited by CVD on either Si or Si/SiO2 substrates and were subjected with pulsed laser annealing (LA). In situ measurements of time-resolved reflectivity revealed strong dependence of melting time on both energy density and type of the substrate. Depending on laser energy density and on type of substrate, initially microcrystalline and amorphous as-deposited layers were transformed to polycrystalline with different morphology and size of the grains. The results are discussed within the model of liquid-phase recrystallization.

This paper discusses the dynamics of photoluminescence excited in CdTe when a pulsed(τ=80ns) ruby laser acts on it, modifying a submicron surface layer. The dependences of the maximum photoluminescence intensity on the irradiation-energy density E are obtained for single, double, and triple laser pulses. The dependences thus established are explained by the influence of competing factors: the increase of the photoexcitation level with increasing E, and the temperature quenching of the photoluminescence. A photoluminescence-increase effect for energy densities above the surface-melting threshold of the semiconductor is detected.

The laser annealing of Ge/Si heterostructures with Ge quantum dots (QD's) embedded on the depth of 0.15 and 0.3 mu m has been studied. The samples were irradiated by 80-nanosecond ruby laser pulses. Irradiation energy density was close to the melting threshold of Si surface. The nanocluster structure was analyzed by Raman spectroscopy. Changes in composition of QD's were observed for both types of samples. The decrease in dispersion of nanocluster sizes after laser irradiation was obtained for samples with QD's embedded on 0.3 pin depth. The numerical simulations on the basis of Stefan problem showed that the maximum temperatures on the depth of QD's bedding differ by similar to 100 K. This difference is likely to lead to different effects of laser annealing of heterostructures with QD's.

Laser-induced phase transitions in a-Ge/Si heterostructures (amorphous Ge films on crystalline Si substrate) have been studied by optical diagnostics and numerical simulation methods. The samples were irradiated by (i) a ruby laser with pulse duration 80 ns (FWHM) and wavelength 694 nm and (ii) an ArF excimer laser (10 ns and 193 nm). Time resolved reflectivity measurements showed the discrepancy in dynamics of reflectivity of probing beam for different regimes of laser irradiation. This discrepancy can be explained by differing kinetics of solid-liquid phase transitions in Ge films: (i) intermediate crystallization or (ii) simultaneous solidification of molten Ge layer from the surface and from the substrate.