Redistribution of Nickel Ions Embedded within Indium Phosphide Via Low Energy Dual Ion Implantations

Transition-metal doped Indium Phosphide (InP) has been studied over several decades for utilization in optoelectronics applications. Recently, interesting magnetic properties have been reported for metal clusters formed at different depths surrounded by a high quality InP lattice. In this work, we have reported accumulation of Ni atoms at various depths in InP via implantation of Ni- followed by H– and subsequently thermal annealing. Prior to the ion implantations, the ion implant depth profile was simulated using an ion-solid interaction code SDTrimSP, incorporating dynamic changes in the target matrix during ion implantation. Initially, 50 keV Ni- ions are implanted with a fluence of 2 × 1015 atoms cm-2, with a simulated peak deposition profile approximately 42 nm from the surface. 50 keV H- ions are then implanted with a fluence of 1.5 × 1016 atoms cm-2. The simulation result indicates that the H- creates damages with a peak defect center ~400 nm below the sample surface. The sample has been annealed at 50°C in an Ar rich environment for approximately 1hr. During the annealing, H vacates the lattice, and the formed nano-cavities act as trapping sites and a gettering effect for Ni diffusion into the substrate. The distribution of Ni atoms in InP samples are estimated by utilizing Rutherford Backscattering Spectrometry and X-ray Photoelectron Spectroscopy based depth profiling while sputtering the sample with Ar-ion beams. In the sample annealed after H implantation, the Ni was found to migrate to deeper depths of 125 nm than the initial end of range of 70 nm

Simultaneous measurement of the average ion-induced electron emission yield and the mean charge for isotachic ions in carbon foils

Article discussing the simultaneous measurement of the average ion-induced electron emission yield and the mean charge for isotachic ions in carbon foils

Mechanism for etching of exfoliated graphene on substrates by low-energy electron irradiation from helium plasma electron sources

Article investigating the mechanism for etching of exfoliated graphene multilayers on SiO₂ by low-energy (50 eV) electron irradiation using He plasma systems for electron sources

Experimental evidence for a discrete transition to channeling for 1.0-MeV protons in Si〈100〉

This article discusses experimental evidence for a discrete transition to channeling for 1.0-MeV protons in Si〈100〉

University Scholars Day

This paper discusses research on modeling and optimization of deflection slits for fast-pulsing of a low energy ion beam. The authors also investigate simulated slit configurations that reduce the length of the fields along the beam axis, thus optimizing the pulsing mechanism

University Scholars Day

Presentation for the 2006 University Scholars Day at the University of North Texas discussing research on modeling and optimization of deflection slits for fast-pulsing of a low energy ion beam

Phase space of positron trajectories exiting a charged particle source through a magnetic field point cusp

This article presents a configuration of magnetic fields using properties of cylindrically symmetric permanent magnets as a candidate to produce a high purity charged particle source or trap. Cylindrically symmetric hollow permanent magnets produce magnetic field point cusps on the axis of symmetry. A magnetic field point cusp reflects all particles that lie outside a narrow region of phase space, a region dependent on particle kinetic energies and on the magnetic field intensity

The angular distribution of atoms sputtered from a Ga-In eutectic alloy target

Angular distributions of sputtered atoms have been obtained for 3, 25, and 50 keV Ar+ bombardment of a liquid Ga-In eutectic alloy target. Sputtered material was collected on graphite foils which were subsequently analyzed by Rutherford backscattering spectroscopy, and the resulting distributions were fit by a functional form, N (θ) α. cos^nθ. For each energy, the angular distribution of sputtered In atoms was overcosine, with n_(In) ≈ 1.8 ±0.1. The distributions of the sputtered Ga atoms were sharper, varying from n_(Ga) ≈ 3.2 ± 0.2 at 25 and 50 keV, to n_(Ga) = 4.9 ± 0.3 at 3 keV. A comparison of the sputtered flux composition with the alloy surface composition profile gives F_1, the fraction of sputtered atoms originating from the first atomic layer. The fraction was found to be f_1 = 0.87 ± 0.01 for 25 and 50 keV bombardment, and increased to 0.94 ± 0.01 at 3 keV. The variations of n_(ga), and F_1 with projectile energy may be the result of a decrease in the average recoil-atom energy for the 3 keV bombardment. The large values found for F_1 support a prediction that the sputtered-atom escape depth is determined by the elastic-collision mean free path of recoil atoms

Sputtering from a liquid Ga-In eutectic alloy

Angular distributions of Ga and In atoms sputtered from a liquid Ga-In eutectic alloy target have been measured for 3, 25, and 50 keV Ar^+ bombardment. Although the bulk composition of the alloy is 16.5 at.% In, thermodynamic surface segregation results in a surface monolayer of > 94 at.% In. A comparison of the measured sputtered-flux composition with the alloy surface composition profile indicates that the fraction of sputtered atoms originating in the first atomic layer, F_1, is ≈ 0.87 at 25 and 50 keV, and increases to 0.94 at 3 keV. Measurements of the secondary-ion flux for 25–250 keV Ar^+ bombardment indicate that F_1 is independent of projectile energy up to 250 keV, in agreement with the predictions of the collision-cascade model. The increase observed at 3 keV may be the result of a decrease in the average energy of recoil atoms participating in the collision cascades

Sticking probabilities for sputtered Ag and Au atoms incident on oxidized aluminum surfaces

We have measured the sticking probabilities for sputtered Ag and Au atoms incident on oxidized aluminum surfaces as a function of the areal density of deposited atoms. For Ag sputtered by 200 keV Ar ions, we found a sticking probability at zero coverage of k(0) = 0.46 ± 0.20. For very high coverages, we found k(n > 10^(17)at./cm^2) = 0.80 ± 0.20. For Au sputtered by 200 keV Ar ions, w found k(0) = 0.92 ± 0.08 and k(n > 10^(17)at./cm^2) = 0.80 ± 0.03. For Au sputtered by 200 keV Xe ions, values of k(0) = 0.98 ± and k(n > 10^(17)at./cm^2) = 0.89 ± 0.03 were obtained. In all cases, the sticking probability varied noticeably for densities between o and twenty monolayers. For Au, a maximum value near 1 was observed in this region while for Ag, the sticking probability exhibited a minimum of approximately 35%. Some possible explanations for these results are offered and the implications for collection-type sputtering experiments are discussed