Electron Beam Annealing Research Articles

Ionic Synthesis of Ga1–xInxAs Solid Solution Films

The Ga1–xIn x As compound obtained by In-ion implantation (100 keV and (0.45–6)·1017 cm–2) followed by thermal (800 °C and 15') or high-energy electron-beam (1 MeV, 0.6 mA·cm–2, 660 °C, and 16 s) annealing is investigated by Rutherford backscattering, optical absorption, and capacitor photoelectromotive force. It is shown that x increases from 0.07 up to 0.21, and the band gap decreases from 1.34 down to 1.21 eV as the implantation dose increases. The surface potential decreases from 0.79 down to 0.58 V. A high efficiency of electron-beam annealing is pointed out.

Current status of plasma emission electronics: II. Hardware

This paper is devoted to the engineering embodiment of the modern methods for producing charged ion and electron beams by extracting them from the plasma of a discharge. Electron beams use to execute electron-beam welding, annealing, and surface heating of materials and to realize plasmochemical reactions stimulated by fast electrons. Ion beams allow realization of technologies of ion implantation or ion-assisted deposition of coatings thereby opening new prospects for the creation of compounds and alloys by the method that makes it possible to obtain desired parameters and functional properties of the surface. A detailed description is given to the performance and design of devices producing beams of this type: the ion and electron sources being developed at the laboratory of plasma sources of the Institute of High-Current Electronics of the Russian Academy of Sciences and the laboratory of plasma electronics of Tomsk State University of Control Systems and Radioelectronics.

Formation of micrometer sized crater shaped pits in silicon by low-energy 22Ne + implantation and electron beam annealing

22Ne + ions were implanted at 20 keV into wafer silicon and annealed at 1100 °C for 15 s (Δ T=5 °C/s) to study the formation of surface structuring. Ion beam analysis measurements revealed that the implanted neon was completely released into the vacuum during the thermal treatment. The surface became structured with the appearance of micrometer sized crater shaped pits with a typical depth of 45 nm. No uptake of carbon, nitrogen and oxygen from air by the specimens during transport and storage was detected making the newly formed structured silicon surfaces interesting for various industrial applications.

Effect of ionization on the behavior of silicon in gallium arsenide subjected to electron-beam annealing

The method of capacitance-voltage characteristics was used to study the behavior of Si implanted into GaAs after a postimplantation electron-beam annealing for 10 s under a beam-power density of 7.6 W cm−2. The electron beam was incident on both the implanted and rear surfaces of the wafers. The reference samples were annealed thermally in a furnace for 30 min at 800°C. It is shown that the diffusion coefficient D is more than three orders of magnitude larger in the case of electron-beam annealing of the implanted surface than in the case of thermal annealing and by almost two orders of magnitude larger than in the case of electron-beam annealing of the rear surface. It is assumed that these distinctions are caused by a long existence time of the high steady-state concentration of nonequilibrium electrons and holes due to their spatial separation.

Effects of Pulsed Electron Beam Annealing on Radiation Damage in N Doped a-SiC:H Films Deposited by PECVD

Effects of Pulsed Electron Beam Annealing on Radiation Damage in N Doped a-SiC:H Films Deposited by PECVD

Height control of silicon nano-whiskers embedded in ultra thin silicon nitride layers by rapid thermal annealing

Two steps are necessary to produce nanometre sized silicon whiskers rising out of ultra thin silicon nitride layers: (i) production of under-stoichiometric silicon nitride surface layers by ion implanting of silicon wafer material, (ii) growth of silicon whiskers by the formation of silicon nitride bonds in the surface region through rapid thermal electron beam annealing. Depending on the implantation and annealing conditions, whiskers of different height and width can be produced. As an example, 25 nm high whiskers were formed by implanting 10 keV 15 N 2 + ions into silicon (fluence 5×10 16 cm −2 ) followed by rapid thermal electron beam annealing at 900°C for 15 s . In atomic force microscope studies, it was observed that the structures became more pronounced with increased temperature. Resonant nuclear reaction analysis revealed the absence of nitrogen in the whiskers and the stoichiometry of the silicon nitride layer formed by implantation.

Effect of the insulator-gallium arsenide boundary on the behavior of silicon in the course of radiation annealing

The depth-concentration profiles n(x) of 28Si implanted into semiinsulating GaAs (E1=50 keV, F1=8.75×1012 cm−2; E2=75 keV, F2=1.88×1012 cm−2) were studied by C-V measurements after the electron-beam annealing (P=7.6 W/cm2, t=10 s). Prior to annealing, the samples were coated with protective insulating films (SiO2:Sm; SiO2 deposited by monosilane oxidation, or Si3N4) or were not coated. It was found that the implant profiles observed upon the electron-beam annealing extend to deeper layers as compared to the calculated curves or the profiles upon thermal annealing (800°C, 30 min). The profile depth depends on the type of insulating coating. The maximum “broadening” was observed in the electron-beam-annealed GaAs without insulating coating, and the minimum, in the sample with a protective SiO2:Sm layer. The n(x) curves can be divided into two parts, adjacent to and distant from the interphase boundary. The diffusion parameters and the degree of electric activation of the implanted Si atoms are greater in the second region than in the first one. The experimental results are interpreted assuming the presence of thermoelastic stresses at the insulator-semiconductor boundary in GaAs.

Production of shallow ion-implanted layers using rapid electron-beam annealing under the condition of transient-enhanced outdiffusion

The effect of the transient-enhanced outdiffusion of P, As, and Sb from ion-doped silicon layers on the diffusion of the impurity into the specimen bulk during rapid electron-beam annealing has been studied. For specimens doped with P+ and As+ ions, it has been established that the average coefficient of diffusion of the impurity into the bulk under the condition of transient-enhanced outdiffusion is a fraction of that in a case where no evaporation of the impurity takes place. For specimens doped with Sb+ ions, no diffusion of antimony into the bulk of silicon under the condition of evaporation of the impurity has been revealed, but, on the contrary, a decrease in the depth of position of the impurity has been detected. The data obtained indicate that the evaporation of the impurity, in particular, its transient-enhanced outdiffusion occurring early in the process of rapid thermal annealing, slows down the diffusion of the impurity into the bulk of silicon. The possibility of harnessing this effect for the production of supershallow-doped layers is discussed.

Effect of wire length on Coulomb blockade in ultrathin wires of recrystallized hydrogenated amorphous silicon

Electron transport in nanowires of hydrogenated amorphous silicon recrystallized by electron beam annealing has been studied. Wire length dependent electrical characteristics have been measured at low temperatures. Evidence for single electron effects with I–V characteristics has been presented. Transmission electron microscopy and photoluminescence data are used to support the electrical results. The Coulomb blockade effect is modeled as a combination of hopping conduction between a limited number of trapping sites in amorphous regions or at grain boundaries with additional Coulomb blockade effects as well as a confinement due to potential fluctuations arising from dopant distribution.

Study of luminescent centers annealing in wide bandgap semiconductors: Color cathodoluminescence-scanning electron microscopy

A color cathodoluminescence-scanning electron microscopy (CCL-SEM) technique was used to study the annealing of luminescent centers in wide bandgap semiconductors (mainly silicon carbide), due to native defects, induced during the growth process or to radiation by high-energy particles. The significant role of dislocations in the crystals was revealed. These dislocations are created by the mechanical failure of crystals and play the role of getters for unstable defects and assist in quenching the luminescence at fairly low annealing temperatures. During the electron beam annealing of the samples, the resolved CL fine structure of luminescence images was measured around failure regions which look like a rosette of strength* at temperatures of 1300–1350°C.

Nonlinear electron transport characteristics in ultrathin wires of recrystallized hydrogenated amorphous silicon

Electron transport in nanowires of hydrogenated amorphous silicon recrystallized by electron beam annealing has been studied. Evidence for single electron effects with I–V characteristics at low temperature has been presented. The region of the nonlinear I–V characteristics is modeled as a hopping conduction between limited number of trapping sites in amorphous regions or at grain boundaries with Coulomb blockade effect. Transmission electron microscopy is used to support this hypothesis.

Effect of radiation annealing on activation of silicon implanted in gallium arsenide

We have investigated the profile of28Si implanted in GaAs obtained by radiation annealing using an electron beam (P=7.6 W/cm2, E=10 keV, t=10 sec, T≅750°C) and thermal annealing in a furnace (T=800°C, t=30 min). It was found that the radiation annealing provides diffusion redistribution of the impurities and a high degree of electrical activation.

TEM investigation of nitrogen-implanted Mo foil

The synthesis and analysis of molybdenum nitrides formed during nitrogen ion implantation were investigated. Molybdenum foil samples were annealed in vacuum at 1750 °C in order to grow large grains with low index preferential orientations. For comparison purposes, thin specimens were also cut from a (110) molybdenum single crystal. These samples were implanted with nitrogen at room temperature as well as at an elevated temperature of 370 °C. Doses of 1×10 17 N + cm −2 and 5×10 17 N + cm −2 were used at accelerating voltages of 50 kV and 100 kV. One nitride phase (MoN) and an unidentified phase were observed under the prevailing conditions. The morphology and orientation relationships of nitride precipitates in the Mo lattice were examined by transmission electron microscopy and electron diffraction. Depending on the surface orientation, both the Bain and the Nishiyama–Wassermann orientations occurred. Implantation at 100 kV resulted in small misorientated MoN precipitates that showed recrystallization and reorientation after annealing at 900 °C. Pulsed electron beam annealing (PEBA) at 0.6 J cm −2 did not affect the nitride precipitates but restored implantation damage in the molybdenum lattice.

The surface chemistry of Hg-containing superconductors by HREM

The surface chemistry of Hg-containing superconductors has been investigated using high resolution electron Microscopy. It was found that the crystal surface of these materials usually decomposed in air by losing Hg, forming a thin amorphous layer containing Ba and Cu. This amorphous layer can be recrystallised into some crystallites of barium cuprate under the electron beam annealing. Such recrystallisation did not take place on the surface of Re-doped Hg-1201. Crystals decomposed heavily when they were ground in solvents. A surface dependence of the low temperature low field magnetic susceptibility of Hg-1201 was also observed.

Pulsed Electron Beam Annealing of GaAs after High Dose Implantation of Hydrogen

Pulsed Electron Beam Annealing of GaAs after High Dose Implantation of Hydrogen

Surface and near surface structure and composition of high-dose implanted and electron beam annealed single crystal copper

Cu(111),(100) single crystals implanted with Ti up to 8 × 10 17 cm −2 followed by high-current electron beam annealing (HCEB) have been investigated by means of transmission electron microscopy (TEM), Rutherford back-scattering (RBS), nuclear reaction elastic resonance (NRER) and scanning electron microscopy (SEM). Ti, O, C concentration profile behaviour in Cu single crystals has been studied. Cu layer structure after Ti implantation became multi-component. It was found that this layer included a surface amorphous carbon film, a layer consisting of TiC, a layer consisting of (110)CuTi/(111)TiC and a subsequent Cu single crystal possessing subgrains of 170–180 nm. A small-angle disorientation up to 5 ° between the subgrains was observed. As a result of HCEB irradiation, a portion of carbon film evaporated, and Ti carbide dispersed to 2–4 nm. The Cu structure essentially changed. The Cu layer contacting the carbide became a nano-dimensional substructure with an average crystallite size of 50–70 nm. At a depth of 0.1 μm the Cu structure is represented as a disoriented striped substructure: the discrete disorientation between the stripes was about 6–7 °. Net dislocation substructure was observed inside the stripes, the dislocation scalar density of which was < γ> = 5.2 × 10 10 cm −2.

Understanding The Role Of Defects In Limiting The Minority Carrier Lifetime In Sic

AbstractDeep level Transient Spectroscopy (DLTS), Electron Beam Induced Current (EBIC), EBIC Diffusion Length Mapping (EBIC-DLM) and contactless Photoconductive Decay (PCD) were used to characterize both bulk substrates and epitaxially grown Silicon Carbide films. Traps as deep as 0.93 eV were observed via DLTS. These traps may play a role in the persistent photoconductivity effect. EBIC reveals the electrical activity of the well known triangular defects. However, only some of these defects display electrical activity consistent with that of 3C-SiC inclusions, others do not. Additionally, not all defects identified in the EBIC images are observable in the topographic SEM image, possibly indicating a new, yet unidentified defect. EBIC revealed the electrical activity of defects including micro-pipes, dislocations (or possibly growth step edge decoration), surface polish damage, and bulk defects. Diffusion length maps of SiC indicate wide variations in diffusion length on both microscopic and macroscopic scales. EBIC-DLMindicatedepitaxial 4H SiC resulted in diffusion lengths from 0.1 to 3 μm, while bulk values were less than 0.07 μm. PCD measurements indicate tens of nanosecond to microsecond variations in lifetime. Lifetime verses injection level variations are observed and explained on the basis of trap energy. The injection level dependence of lifetime was observed at various nitrogen doping concentrations. Finally, electron beam annealing is found to dramatically improve the minority carrier lifetime in epitaxial SiC.

Scanning electron beam annealing of sputter-deposited titanium on silicon

Ti thin films sputter-deposited on single crystal Si wafers were annealed by using a scanning electron beam source. The resulting titanium silicides have been characterized by RBS and X-ray diffraction techniques. The experimental results show that the initial Ti layer thickness, in the studied range of 50 to 500 nm, does not affect the amount of formed silicide. RBS measurements are not enough to deduce the silicide composition due to the lack of well defined interfaces. X-ray measurements indicate the presence of only a single silicide phase, Ti 5Si 4. These results indicate that the interfaces in the structure Ti-silicide-Si, resulting from the e-beam treatment, are corrugated.

Granular superconductor contacts to two-dimensional electron gases

Superconducting contacts are made to a buried two-dimensional electron gas using metal multilayers (Sn:Cr:Au) patterned by electron-beam lithography, and sintered using rapid electron-beam annealing. The contact structure has been analyzed using transmission electron microscopy and high-resolution scanning electron microscopy, and many alloys are found to be present, but the structure is predominantly a honeycomb mixture of AuSn4 and CrAs. The resultant contacts are granular superconductors with relatively high critical temperatures of 5–7.5 K.

Fundamental studies of p-type doping of CdTe

This paper reviews recent developments of p-type doping in CdTe, in which hole concentrations of 5 × 10 19cm −3 have been obtained with phosphorus ion implantation and pulsed electron beam annealing. The implant and damage profiles, and the atom redistribution after the annealing were calculated to explain the experimental results. Defect models were proposed to further illustrate the doping mechanisms. The creation and the annihilation of the phosphorus interstitials were explained by analyzing the electronic structure of the phosphorus interstitial following a molecular orbital approach and density functional theory. All these results confirmed the importance of the melting effect of pulsed electron beam (PEB) annealing in obtaining the highest doping efficiencies in II–VI compounds.