Ion mixing of markers in SiO2 and Si

The amount of atomic mixing in amorphous SiO2 and Si is studied by measuring the redistribution of thin metal markers due to irradiation with 300-keV Xe+ ions. In SiO2, the mixing efficiency appears to be independent of the chemical nature of marker atoms and can be explained in terms of a linear cascade model. In Si, the mixing is found to correlate with thermally activated diffusivities of the marker species

Microstructure and Thermal Stability of Transition Metal Nitrides and Borides on GaN

Microstructure and thermal stability of ZrN/ZrB2 bilayer deposited on GaN have been studied using transmission electron microscopy methods (TEM) and secondary ion mass spectrometry (SIMS). It has been demonstrated that annealing of the contact structure at 1100 C in N2 atmosphere does not lead to any observable metal/ semiconductor interaction. In contrast, a failure of the integrity of ZrN/ZrB2 metallization at 800 C, when the heat treatment is performed in O2 ambient has been observed

Origin of Magnetic Circular Dichroism in GaMnAs: Giant Zeeman Splitting versus Spin Dependent Density of States

We present a unified interpretation of experimentally observed magnetic circular dichroism (MCD) in the ferromagnetic semiconductor (Ga,Mn)As, based on theoretical arguments, which demonstrates that MCD in this material arises primarily from a difference in the density of spin-up and spin-down states in the valence band brought about by the presence of the Mn impurity band, rather than being primarily due to the Zeeman splitting of electronic states.Comment: 4+ pages, 4 figure

MICROSTRUCTURE AND THERMAL STABILITY OF TRANSITION METAL NITRIDES AND BORIDES ON GaN

ABSTRACT Microstructure and thermal stability of ZrN/ZrB 2 bilayer deposited on GaN have been studied using transmission electron microscopy methods (TEM) and secondary ion mass spectrometry (SIMS). It has been demonstrated that annealing of the contact structure at 1100 0 C in N 2 atmosphere does not lead to any observable metal/ semiconductor interaction. In contrast, a failure of the integrity of ZrN/ZrB 2 metallization at 800 0 C, when the heat treatment is performed in O 2 ambient has been observed

Observation of surface states on heavily indium doped SnTe(111), a superconducting topological crystalline insulator

The topological crystalline insulator tin telluride is known to host superconductivity when doped with indium (Sn$_{1-x}$In$_{x}$Te), and for low indium contents ($x=0.04$) it is known that the topological surface states are preserved. Here we present the growth, characterization and angle resolved photoemission spectroscopy analysis of samples with much heavier In doping (up to $x\approx0.4$), a regime where the superconducting temperature is increased nearly fourfold. We demonstrate that despite strong p-type doping, Dirac-like surface states persist

Defects in high temperature and high pressure processed Si:N revealed by deuterium plasma treatment

Deuterium is accumulated by defects in nitrogen-implanted silicon (Si:N). This effect is investigated for Si:N processed at HT ≤ 1400 K, also under enhanced hydrostatic pressure, HP ≤ 1.1 GPa. Si:N was prepared from Czochralski grown silicon by N₂⁺ implantation at E = 140 keV with nitrogen doses, DN = 1–1.8•10¹⁸ cm⁻². Si:N was subsequently processed in RF deuterium plasma to prepare Si:N,D. Si:N and Si:N,D were investigated by Transmission Electron Microscopy (TEM), X-ray and Secondary Ion Mass Spec- trometry (SIMS) methods, also after additional annealing at 723 K. In heavily implanted Si:N (DN = 1.8•1010¹⁸ cm⁻²), plasma treatment leads to deuterium pile up to сD1 = 2•10²¹ cm⁻³ at a depth, d = 50 nm, while, at d = 80–250 nm, deuterium concentration is practically constant with сD2 = 1•10²¹ cm⁻³. This suggests dominating accumulation of deuterium within the bubble-containing areas. Determination of deuterium depth profiles in Si:N,D can reveal implantation- and processing-induced defects.В работе рассмотрены эффекты влияния обработки температурным отжигом (до 1400 K) и гидростатическим давлением (до 1.1 GPa) на дефектный состав SOI-структур (silicon-on-insulator) на основе образцов Si:N – материала, широко используемого в полупроводниковых технологиях. Были получены новые данные, свидетельствующие об образовании скрытых дефектосодержащих слоев в образцах кремния, имплантированного азотом, и подвергнутых обработке высокими температурами и давлениями. Такие структуры становятся центрами абсорбции дейтерия из плазмы – его накопление и распределение внутри образца зависят от микроструктуры материала. Таким образом, показано, что обработка в дейтериевой плазме с дальнейшим определением концентрационных профилей по глубине образца может быть полезной для оценки микроструктурыУ роботі розглянуто ефекти впливу обробки температурним відпалом (до 1400 K) і гідростатичним тиском (до 1.1 GPa) на дефектний склад SOI-структур (silicon-oninsulator) на основі зразків Si:N – матеріалу, широко використовуваного в напівпровідникових технологіях. Було отримано нові дані, що свідчать про утворення прихованих дефектовміщуючих шарів в зразках кремнію, імплантованого азотом, підданих обробці високими температурами та тиском. Такі структури стають центрами абсорбції дейтерію з плазми – його накопичення і розподіл усередині зразка залежать від мікроструктури матеріалу. Таким чином, показано, що обробка в дейтерієвій плазмі з подальшим визначенням концентраційних профілів по глибині зразка може бути корисною для оцінки мікроструктури Si:N-зразка, особливо зважаючи на потенційну застосовність в SOI-технологіях

Pressure-induced structural transformations in Si:V and Si:V, Mn

Semiconductors doped with magnetically active atoms are expected to find application in spintronics. Si samples implanted with Mn⁺ (Si:Mn) or with V⁺ (Si:V) can order magnetically after processing at high temperature (HT) and also under enhanced hydrostatic pressure (HP). This work presents new results on structure-related properties of single crystalline Si implanted at 200 keV with V⁺ as well as that co-implanted additionally with Mn⁺ ions (Si:V, Mn), with dosages DV⁺ ≤ 5·10¹⁵ cm⁻² and DMn⁺ = 1·10¹⁵ cm⁻². The samples were processed for 1–5 h at HT ≤ 1270 K under HP ≤ 1.1 GPa. Secondary Ion Mass Spectrometry, Transmission Electron Microscopy, X-ray and related methods were applied for sample characterization. The HT- (HP) treatment affects, among others, solid phase epitaxial re-growth (SPER) of amorphous silicon created at implantation and distribution of implanted species

Analysis of Crystal Lattice Deformation by Ion Channeling

A model of dislocations has been developed for the use in Monte Carlo simulations of ion channeling spectra obtained for defected crystals. High resolution transmission electron microscopy micrographs show that the dominant type of defects in the majority of ion irradiated crystals are dislocations. The RBS/channeling spectrum is then composed of two components: one is due to direct scattering on randomly displaced atoms and the second one is related to beam defocussing on dislocations, which produce predominantly crystal lattice distortions, i.e. bent channels. In order to provide a correct analysis of backscattering spectra for the crystals containing dislocations we have modied the existing Monte Carlo simulation code McChasy. A new version of the code has been developed by implementing dislocations on the basis of the PeierlsNabarro model. Parameters of the model have been determined from the high resolution transmission electron microscopy data. The newly developed method has been used to study the Ar-ion bombarded SrTiO3 samples. The best t to the Rutherford backscattering/channeling spectra has been obtained by optimizing the linear combination of two kinds of defects: displaced atoms and bent channels. The great virtue of the Monte Carlo simulation is that unlike a traditional dechanneling analysis it allows quantitative analysis of crystals containing a mixture of dierent types of defects