[en] Silicon doping profiles with low-energy boron ions depending on energy, radiation dose, target orientation and implantation temperature were investigated. The measurements were performed using electrophysical methods after activation of the implanted impurity with annealing as well as the secondary ion mass spectrometry method. It is shown that the observed deep boron penetration is related to channeling. A share of channeling ions is preserved high enough up to a dose of 10₁₅ cm^-₂ even at 20 deg C, which testifies to a low level of the lattice disordering produced with low energy boron ions. It is noted that the use of low-energy ion channeling is perspective for the doping of layers of the strictly given thickness, and calculated evaluations of channeling parameters of different mass impurity ions in the energy range of 1-10 keV are given

[en] Short note

[en] 5 keV boron ions and 1.8 keV phosphorus ions are implanted into silicon along <110> at target temperatures of 200-400 deg C. High-alloyed layers of the p- and n-types of 260 and 180 nm, accordingly, have been produced after annealing. Layer thicknesses exceed mean projective disordered ion paths more than by an order. Deep impurity penetration doesn't depend on irradiation temperature in the range investigated and is not related to the diffusion during the annealing. Alloyed layer thickness correspond to the calculated maximum ion paths in channels. The results obtained are attributed to channelling, at that, increased irradiation temperature prevents the defect accumulation and choking up channels as increasing a dose and use of low energy ions increases a critical channelling angle. The annealing with light pulses of millisecond range provides practically complete electric activation of impurity up to 10¹⁶ cm^-2 dose and doesn't lead to its redistribution. The alloying version considered permits to introduce impurity at depths characteristic of common ion implantation however doesn't require complex and expensive apparatuses as well as is characterized with a lower level of material damage and decreased ion side scattering

[en] Implanted donors and lattice defects, accompanying implantation, alter the Schottky barrier height in a similar manner, which introduces uncertainty in revealing the physics of the process. In order to increase the effective height of Schottky barriers in Al-n-Si, we implanted acceptor ions (Ga with E=6-7 keV). The thermal treatment was performed in the process or after the irradiation. The annealing temperature 650 deg and the irradiation temperature 550 deg without the additional thermal treatment were sufficient to increase the barriers height, which indicated the impurity nature of the effect. The parameters of the barriers were studied as a function of the implantation conditions. Variation of the heights within 0.66-0.85 eV was attained with ideality factors β=1.09-1.2 and rectification factors 10⁵-10⁶. Worsening of the structure parameters at irradiation temperatures above 750 deg was attributed to the radiation-enhanced diffusion of gallium

[en] Silicon of p type was exposed to phosphorus ions of 600 eV energy at a substrate temperature up to 800 deg C. Ion current density amounted to approximately 1 mA/cm², exposure time - up to 300 s. 0.3 μm thick doped layers of n type having high values of concentration and mobility of free carriers have been produced. Calculations suggesting phosphorus diffusion acceleration by excess vacancies agree with experimental results. High-temperature irradiation with low-energy ions does not result in disordered areas, prevents defect accumulation and does not reguire additional annealing as compared with common ion implantation. Electron microscopy has not revealed damages characteristic of implanted and thermally annealed layers in the doped layer. As the impurity penetration mechanism into the substrate is diffusive, doping by means of high-temperature irradiation with low-energy ions is suggested to call the ion injection or injection doping unlike the ion implantation

[en] A quantitative analysis of the impurity penetration into silicon under a low energy ion bombardment has been performed in terms of a vacancy-enhanced diffusion model. It is found that the energy dependence of the diffusion enhancement is due not to the interaction of vacancies with the surface, but to a change of the number of displacements in the spike and its size. An increase of the target temperature from 600 to 850 deg suppresses the formation of sinks for mobile vacancies which leads to a considerable growth of the diffusion efficiency. It is shown that decrease of the diffusion enhancement with increasing dose cannot be explained exclusively by the impurity deposition on the bombardment-induced sinks; it is mainly due to a decrease of the lifetime of free vacancies

[en] N-type Si(110) was irradiated by Si⁺ ions with energies 3, 5, 10 and 20 keV at farget temperatures 20-400 deg C. The character of the lattice depth disorder was studied using reflection electron diffraction method combined with layer-by-layer etching and by means of He⁺ ions backscattering. It is shown that at room temperature irradiation for energies of 10 keV and higher amorphization first ensues in the bulk. Starting from the energy of 5 keV with the same total expenditures for elastic losses the surface amorphization is predominant. The result is explained by the fact that with decrease of the ion energy a relative fraction of mobile point defects is increased, and the fraction of immobile defect clusters responsible for the nucleation of the amorphous phase in the bulk is decreased. The temperature of the surface amorphization suppression lies within 200-33 deg, that is noticeably higher the irradiation temperatures when the bulk amorphization is still possible at the same total elastic losses

[en] Hall measurements, SIMS and TEM have been used for investigation of the silicon surface irradiated with 1.7-7 keV gallium ions at the target temperatures 550-950 deg. It is shown that ''hot'' irradiation produces in a controllable manner heavily doped p-type several hundred nanometers thick surface layers. Penetration of impurity atoms far beyond the mean ion ranges is attributed to the radiation enhanced diffusion under the ''hot'' ion bombardment (ion injection). The injected impurity atoms were found to be completely electrically active. TEM of injected layers reveals no structural damage, inherent to conventional ion implantation with high temperature post bombardment annealing

[en] Pseudomorphous Ge films have been deposited on Si(0 0 1) substrate using molecular beam epitaxy at 300 deg. C up to the critical thickness of four monolayers. As a result of the following deposition pyramid-like Ge islands have been grown in Stranski-Krastanov mode. The islands revealing quantum dots (QD) properties are self-organized during the growth in uniform Ge nanostructures with lateral sizes ∼15 nm and height ∼1.5 nm. Ge K XAFS measurements have been performed using total electron yield detection mode. It was established that pseudomorphous 4-monolayer Ge films contain about 50% Si atoms. It has been found that the Ge QD are characterized by interatomic Ge-Ge distances of 2.41 A which is 0.04 A less than in bulk Ge

[en] GeK XAFS measurements have been performed using the total electron yield detection mode for pseudomorphous Ge films deposited on Si(0 0 1) substrate via molecular beam epitaxy at 300 deg. C. The samples have been produced by thrice repeating the growing procedure separated by deposition of blocking Si layers at 500 deg. C. The local microstructure parameters (interatomic distances, Ge coordination numbers) are linked to nanostructure morphology and adequate models are suggested and discussed. It was established that pseudomorphous 4-monolayer Ge films contain 50% of Si atoms on the average. Pyramid-like, pure Ge islands formed in the Stranski-Krastanov growth are characterized by the interatomic Ge-Ge distances of 2.41 A (by 0.04 A less than in bulk Ge) and the Ge-Si distances of 2.37 A. It was revealed that the pure Ge nanoclusters are covered by a 1-2-monolayer film with admixture on the average of a 50% Si atom impurity from blocking Si layers