Ion-beam-induced porosity of GaN (original) (raw)

Swelling or erosion on the surface of patterned GaN damaged by heavy ion implantation

Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2010

Wurtzite undoped GaN epilayers (0 0 0 1) was implanted with 500 keV Au + ions at room temperature under different doses, respectively. Ion implantation was performed through photoresist masks on GaN to produce alternating strips. The experimental results showed that the step height of swelling and decomposition in implanted GaN depended on ion dose and annealing temperature, i.e., damage level and its evolution. This damage evolution is contributed to implantation-induced defect production, and defect migration/accumulation occurred at different levels of displacement per atom. The results suggest that the swelling is due to the formation of porous structures in the amorphous region of implanted GaN. The decomposition of implanted area can be attributed to the disorder saturation and the diffusion of surface amorphous layer.

GaN evaporation and enhanced diffusion of Ar during high-temperature ion implantation

Journal of Applied Physics, 2003

GaN films were implanted with 150 keV Ar ϩ at temperatures up to 1100°C to a dose of 3 ϫ10 15 cm Ϫ2 . Concentration profiles of Ar were measured by secondary ion mass spectroscopy and depth distributions of ion-induced damage were estimated from Rutherford backscattering/ channeling spectra. No redistribution of Ar atoms was detected up to 700°C. At 1000°C a deep penetrating diffusion tail and a shift of the Ar peak to the surface were observed. At temperatures higher than 800°C shift of the damage peak to the surface was also observed. We attributed the shift of the Ar peak and the damage peaks to evaporation of thin layer of GaN during high-temperature implantation and estimated its temperature dependence.

Three-step amorphisation process in ion-implanted GaN at 15 K

Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions With Materials and Atoms, 2003

GaN layers were implanted at 15 K with 150 keV O, 300 keV Ar or 800 keV Xe ions. The subsequent damage analysis was performed by Rutherford backscattering of He ions in channelling configuration at the same temperature. At this low temperature thermal effects can be widely excluded. However, the dependence of the damage concentration on the ion fluence suggests that the damage evolution in GaN is dominated by a pronounced recombination of the primarily produced defects within the collision cascades. Furthermore, a strong influence of the ions themselves has to be assumed in order to understand the experimental results. Such effects occur already at rather low ion fluences. Our results indicate an amorphisation of GaN proceeding in three steps.

Ion implantation effects on the microhardness and microstructure of GaN

Journal of Crystal Growth, 2001

We study the effect of N + and O + implantation on the microhardness and the microstructure of epitaxially grown GaN. The microhardness is measured using a Knoop diamond indenter while information on the effect of implantation on the surface morphology, microstructure and electronic structure is provided by atomic force microscopy, crosssection transmission electron microscopy and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. It is demonstrated that implantation increases the surface microhardness. A possible mechanism for the surface hardening effect is based on the formation of N interstitials that pin the dislocations and prohibit the plastic deformation. In addition to the hardening effect, the implantation induced N interstitials introduce a characteristic resonance in the NEXAFS spectra, at 1.4 eV below the absorption edge. #

Ion beam deposition and in-situ ion beam analysis

Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 1992

The direct deposition in thin films and the production of very shallow junctions by ultralow energy ion implantation involves the interaction of ions with only the outermost surface layers of a solid. Quantitative structural and composition analysis of the grown or implanted layers requires the use of techniques with extremely high depth resolution. The growth of Si epitaxially on Si (100) substrates prepared by a variety of ion beam and thermal treatments has illustrated the complex radiation effects that occur in the bombardment energy range from 20 to 500 eV. These effects have been studied using medium energy ion scattering in the double alignment mode. With a 50 keV H+ beam, a high resolution electrostatic analyser and incidence and emergence directions aligned with the [111¯] and [3¯3¯1] directions, a depth resolution of 3 Å can be obtained. The effects of ion energy on the structure of grown films and on the damage in the substrate during pretreatment with Cl+ and Ar+ ions will be described.

Effect of ion species on implantation-produced disorder in GaN at liquid nitrogen temperature

Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2002

The effect of ion species on the damage buildup behavior in wurtzite GaN under bombardment at liquid nitrogen temperature (LN2) is studied by a combination of Rutherford backscattering/channeling spectrometry and transmission electron microscopy. Results show that both the density of collision cascades and chemical effects of implanted species affect the damage buildup behavior during bombardment at LN2. In particular, an

A study of the structural properties of GaN implanted by various rare-earth ions

Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions With Materials and Atoms, 2013

GaN layers with <0001> crystallographic orientation, grown by low-pressure metal-organic vapour-phase epitaxy (MOVPE) on c-plane sapphire substrates, were implanted with 200 and 400 keV Sm + , Tm + , Eu + , Tb + and Ho + ions at fluencies of 1×10 15 -1×10 16 cm −2 . The composition of the ion-implanted layers and concentration profiles of the implanted atoms were studied by Rutherford Back-Scattering spectrometry (RBS). The profiles were compared to SRIM 2012 simulations. The structural properties of the ion-implanted layers were characterised by RBS-channelling and Raman spectroscopy. Changes in the surface morphology caused by the ion implantation were examined by Atomic Force Microscopy (AFM). A structural analysis showed a high disorder of the atoms close to the amorphised structure at the surface layer above an implantation fluence of 5x10 15 cm -2 while lower disorder density was observed in the bulk according to the projected range of 400 keV ions.

Donage and in Situ Annealing During Ion Implantation

MRS Proceedings, 1982

ABSTRACTFormation of amorphous (α) layers in Si during ion implantation in the energy range 100 KeV–11MeV and temperature range liquid nitrogen (LN)-100°C has been investigated.Cross-sectional transmission electron microscopy (XTEM) shows that buried amorphous layers can be created for both room temperature (RT) and LN temperature implants, with a wider 100 percent amorphous region for the LN cooled case. The relative narrowing of the α layer during RT implantation is attributed to in situ annealing. Implantation to the same fluence at temperatures above 100°C does not produce αlayers. To further investigate in situ annealing effects, specimens already containing buried α layers were further irradiated with ion beams in the temperature range RT-400°C. It was found that isolated small α zones (< 50 Å diameter)embedded in the crystalline matrix near the two α/c interfaces dissolved into the crystal but the thickness of the 100 percent α layer was not appreciably affected by further...