Unimplanted Samples Research Articles

Evaluation of argon ion impact parameters in aluminium oxide by means of SRIM program and investigation of the effect of argon ion implantation on the thermoluminescence properties aluminium oxide

The thermoluminescence properties of aluminium oxide (alumina) implanted with 80 keV argon ions at fluences in the range of were investigated. The unimplanted and implanted samples were irradiated at a dose of 40 Gy and heated at a rate of 1°C/s. The glow curve of unimplanted and implanted samples shows 5 distinct peaks; the main dosimetric peak and four other peaks of lower intensity. In this study, our analysis has focussed on the main dosimetric peak located at 180°C, 191°C, 177°C, 208°C, 219°C and 207°C for the unimplanted sample and implanted samples respectively. It was observed that the TL intensity decreases with fluence of implantation. This suggests that ion implantation decreases the concentration of electron traps responsible for thermoluminescence. It can also be suggested that competition effects involving radiative pathways and non-radiative competitor traps may lead to a low thermoluminescence signal in the implanted samples in comparison to the unimplanted thermoluminescence signal. These competitive processes will tend to favour first-order kinetics, and consequently lead to a strong stability of the glow curve shapes. The creation of defect clusters as well as extended defects could also be responsible for the reduction in TL signal. The stopping and range of atoms in matter (SRIM) was used to evaluate the ion impact parameters including ion range, vacancy distribution and energy loss in Al2O3. Subsequent to ion implantation, it was found that the number of oxygen vacancies which are related to electron traps are higher than the number of aluminium vacancies. Kinetic analysis was carried out by means of the initial rise, Chen’s peak shape, various heating rate, the whole glow curve, glow curve fitting and isothermal decay methods. The activation energy was found to be around and the frequency factor to be of the order regardless of the implantation fluence. The dosimetric features of samples were also investigated at doses in the range of 40–200 Gy. Samples generally showed a superlinear response at doses less than 140 Gy and sublinear response at doses higher than 160 Gy.

Raman and RBS Analysis of Silicon Ion Implanted Gallium Arsenide

This paper analyzes the effect of 100[Formula: see text]keV silicon negative ion implantation in semi-insulating gallium arsenide sample for the fluences varying between [Formula: see text] and [Formula: see text][Formula: see text]ion[Formula: see text]cm[Formula: see text] using Raman spectroscopy, Rutherford backscattering spectroscopy and Electron spin resonance spectroscopy. The gallium arsenide sample implanted with silicon negative ion for different fluences showed shift in the TO peak position with respect to unimplanted gallium arsenide sample. Increase in the broadening of TO peak was observed in the as-implanted samples, indicating development of stress and phonon confinement due to the incorporation of silicon in gallium arsenide crystal lattice. Annealing of as-implanted samples showed stress relaxation. Increase in RBS backscattering yield was observed in the as-implanted samples. Annealing of as-implanted (with high fluence) sample showed flat RBS yield response. ESR measurement study revealed restructuring of defects in the gallium arsenide sample implanted with fluence of [Formula: see text][Formula: see text]ion[Formula: see text]cm[Formula: see text] after annealing to the temperature of [Formula: see text]C.

Effect of Nitrogen Ion Implantation Energy on the Mechanical and Chemical Properties of AISI M50 Steel

Nitrogen ion implantation has shown its role in enhancing steel surface properties. In this work, AISI M50 steel was implanted with nitrogen ions by using the metal vapor vacuum arc technique with a dose of 2 × 1017 cm−2, and corresponding implanted energies were at 60 keV, 80 keV, and 100 keV, respectively. The distribution of implanted nitrogen ions was calculated, and the samples were tribologically tested and examined. As shown by the results, the microhardness in implanted samples was 1.17 times greater relative to that of the unimplanted sample. The implantation of the nitrogen ion leads to a change in the friction coefficient of the AISI M50 steel. Adhesive wear mechanism occurs in the unimplanted sample, and adhesion resistance tends to increase when nitrogen-implanted energy increases. The formation of oxides α-Fe2O3 and Fe3O4 further enhanced the tribological properties for implanted samples.

Structural, optical and dielectric properties of (Co and Sm) co-implanting O-polar ZnO films on sapphire substrate

In this paper, molecular beam epitaxy (MBE) was used to prepare O-polar ZnO films on the sapphire substrate. Co ions and Sm ions were respectively injected into the O-polar ZnO films by ion implantation, so that Co-implanted O-polar ZnO film, Sm-implanted O-polar ZnO film, and (Co and Sm) co-implanted O-polar ZnO film were prepared. We adopted X-ray diffraction (XRD), Atomic Force Microscope (AFM), Raman spectroscopy, photoluminescence spectra (PL), absorption spectroscopy and Spectroscopic Ellipsometry (SE) to study the structure, optical and dielectric properties of all samples. XRD showed that Co atoms and Sm atoms had entered the crystal lattice and the high-quality ZnO films had been prepared. Compared with the unimplanted sample, the surfaces of the implanted samples were granular and the roughness became larger. The co-implanted sample had the smaller roughness than the single-implanted samples. It was found from Raman spectra that two modes related to the LO vibration mode appeared near 50–230 cm−1 and 520–570 cm−1 after implantation. The PL spectra indicated that the intensity of the Sm-implanted sample was greater than the (Co and Sm) co-implanted sample. After ion implantation, the results measured by SE showed the band gap values of the (Co and Sm) co-implanted sample was reduced, and a transition peak around 3.15 eV appears in the second-order derivative spectra of the imaginary part ε2 of the dielectric function. These paved the way for their application and development in optoelectronic devices.

Effects of Titanium-Implanted Dose on the Tribological Properties of 316L Stainless Steel

The effects of titanium (Ti) ion-implanted doses on the chemical composition, surface roughness, mechanical properties, as well as tribological properties of 316L austenitic stainless steel are investigated in this paper. The Ti ion implantations were carried out at an energy of 40 kV and at 2 mA for different doses of 3.0 × 1016, 1.0 × 1017, 1.0 × 1018, and 1.7 × 1018 ions/cm2. The results showed that a new phase (Cr2Ti) was detected, and the concentrations of Ti and C increased obviously when the dose exceeded 1.0 × 1017 ions/cm2. The surface roughness can be significantly reduced after Ti ion implantation. The nano-hardness increased from 3.44 to 5.21 GPa at a Ti ion-implanted dose increase up to 1.0 × 1018 ions/cm2. The friction coefficient decreased from 0.78 for un-implanted samples to 0.68 for a sample at the dose of 1.7 × 1018 ions/cm2. The wear rate was slightly improved when the sample implanted Ti ion at a dose of 1.0 × 1018 ions/cm2. Adhesive wear and oxidation wear are the main wear mechanisms, and a slightly abrasive wear is observed during sliding. Oxidation wear was improved significantly as the implantation dose increased.

Влияние дополнительной имплантации ионов кислорода на дислокационную люминесценцию кремния, содержащего кислородные преципитаты

Dislocation-related photoluminescence is studied in unimplanted and implanted with oxygen ions silicon wafers after multistage heat treatment, used for the formation of internal getter in microelectronics, and final annealing at 1000°С in a chlorine-containing atmosphere. In unimplanted sample, the dislocation-related luminescence line D1 dominates and its intensity is more than one order of magnitude in comparison with another dislocation-related luminescence line D2. With increasing temperature, an intensity of the D1 line increases and then decreases. In implanted sample, the intensities of the D1 and D2 lines increase. For both the lines, temperature quenching of their intensities is observed only. The energies of quenching and increase of the intensities of dislocation-related photoluminescence lines are determined. Possible reasons of observed effects are discussed.

Structural and mechanical properties of tantalum thin films ected by nitrogen ion implantation

Tantalum bulk were implanted with nitrogen ions at different dose of [Formula: see text] ions/cm2 to [Formula: see text] ions/cm2 and at a energy 30 keV. The implanted samples were characterized using X-ray diffraction (XRD), atomic force microscopy (AFM), microhardness testing, friction coefficient measurements and wear mechanism study. Scanning electron microscopy (SEM) images were used to analyze the friction of samples. The XRD results confirmed that the increasing dose affects the formation of the TaN phase. Based on AFM images, the morphology and surface roughness change proportionally to grain size after implantation. It was found that hardness increases as energy increases. From the friction coefficient measurement, this coefficient decreases as energy increases. For the un-implanted sample, the wear mechanism has abrasion, and with increasing the energy, it shifts to being flake and sticky.

Study of Low Energy (50 keV) Silicon Negative ion Implantation in GaAs

In the present work, semi - insulating GaAs samples implanted with 50 keV silicon negative ions with fluences varying from 1 x 10 14 to 1 x 10 16 ions cm -2 have been investigated using scanning electron microscopy, atomic force microscopy and X-ray diffraction techniques. Scanning electron microscopy showed presence of pores on the surface of implanted samples. Energy dispersive X-ray analysis showed the increase in silicon concentration in GaAs sample from 1.00 atomic % for sample implanted with 1 x 10 15 ion cm -2 to 1.30 atomic % for sample implanted with 1 x 10 16 ion cm -2 . Atomic force microscopy showed Lorentzian distribution of nano - structured hillocks on the surface of sample implanted up to the fluence of 1 x 10 15 ion cm -2 . X-ray diffraction spectra showed increase in intensity of GaAs (400) Bragg’s peak for sample implanted with the fluence of 1 x 10 16 ion cm -2 compared to un-implanted sample

Intersubband Absorption in Gallium Arsenide Implanted with Silicon Negative Ions

Gallium arsenide (GaAs) implanted with silicon forming intersubband of SiGaAs is a promising material for making novel electronic and optoelectronic devices. This paper is focused on finding optimum fluence condition for formation of intersubband of SiGaAs in GaAs sample after implantation with 50[Formula: see text]keV silicon negative ions with fluences varying between [Formula: see text] and [Formula: see text] ions cm[Formula: see text]. The GaAs samples were investigated using X-ray photoelectron spectroscopy (XPS), UV-Vis.-NIR spectroscopy and X-ray diffraction (XRD) techniques. The X-ray photoelectron spectra for unimplanted sample showed peaks at binding energy of 18.74[Formula: see text]eV and 40.74[Formula: see text]eV indicating Ga3d and As3d core level, whereas the corresponding core level peaks for implanted sample were observed at binding energy of 19.25[Formula: see text]eV and 41.32[Formula: see text]eV. The shift in Ga3d and As3d core levels towards higher binding energy side in the implanted sample with respect to unimplanted sample were indicative of change in chemical state environment of Ga–As bond. The relative atomic percentage concentration of elemental composition measured using casa XPS software showed change in As/Ga ratio from 0.89 for unimplanted sample to 1.13 for sample implanted with the fluence of [Formula: see text] ion cm[Formula: see text]. The UV-Vis-NIR spectra showed absorption band between 1.365[Formula: see text]eV and 1.375[Formula: see text]eV due to the formation of intersubband of SiGaAs for fluences greater than [Formula: see text] ion cm[Formula: see text]. The GaAs crystallite size calculated using Brus formula was found to vary between 162[Formula: see text]nm and 540[Formula: see text]nm, respectively. The XRD spectra showed the presence of Bragg’s peak at 53.98∘ indicating (311) silicon reflection. The silicon crystallite size determined from full width at half maxima (FWHM) of (311) XRD peak was found to vary between 110[Formula: see text]nm and 161[Formula: see text]nm, respectively.

Structural and optical characteristics investigations in oxygen ion implanted GaN epitaxial layers

This paper presents the lattice disorder-induced effect by oxygen ion implantation in GaN epitaxial layers. Oxygen ion implantation in GaN epitaxial layers is done with fluencies 5 × 1014 cm−2 and 5 × 1015 cm−2 at 120 keV energy on two different pieces of a GaN sample. Unimplanted and implanted GaN layers are investigated by High-resolution X-ray diffraction (HRXRD), Optical absorption and Raman spectroscopy. The in-plane and out of plane lattice parameters (i.e. a and c) of the distorted and undistorted region in the GaN samples are determined from the respective XRD peak positions. Due to the incorporation of oxygen ions in GaN layers up to implantation depth, lattice parameters are extended, as a result, the samples are under hydrostatic strain. Raman spectroscopic studies on the unimplanted and oxygen ion-implanted GaN samples are done by green and ultra-violet (UV) lasers. Raman spectroscopy results indicate that the broadening of the E2 (High) peak and intensity of A1 (LO) peak increases with increasing fluence. A doublet in A1 (LO) peak is found in UV excited Raman spectra in unimplanted and implanted GaN samples. The occurrence of the A1 (LO) doublet is due to surface defects and phonon-plasmon coupled-mode generated due to nonequilibrium photoexcited carriers. In this article, the origin of doublet has been studied and reported.

Realization of GaN-based gain-guided blue laser diodes by helium ion implantation

The fabrication process and characteristics of gallium nitride (GaN) based gain-guided blue laser diodes (LDs) are studied, in which an ion implantation process is adopted to confine carrier injection into the active region. The implantation of helium ions with an energy of 85 keV, an angle of 0°, and a dosage of 4.7 × 1014 cm−2 is conducted in the experiment. The specific contact resistivity of p-type ohmic contact of implanted sample is determined to be 2.2 × 10–4 Ω cm2, which is comparable with the un-implanted sample. Then, both ion-implanted gain-guided and ridge waveguide LDs are fabricated at the same time. Similar threshold current density and slope efficiency are obtained, while the operation voltage of ion-implanted gain-guided LDs is 0.2 V lower than the ridge waveguide LDs at 0.56 kA cm−2. The ridge waveguide LDs show multi-mode operation after lasing. However, for ion-implanted gain-guided LDs, the far-field pattern indicates a single lateral mode operation up to twice of the threshold current, and the peak optical output power of blue single mode LDs at 450 nm exceeds 200 mW under pulsed condition.

Impurity-enhanced solid-state amorphization: the Ni–Si thin film reaction altered by nitrogen

Solid-state amorphization, the growth of an amorphous phase during annealing, has been studied in a wide variety of thin film structures. Whereas research on the remarkable growth of such a metastable phase has mostly focused on strictly binary systems, far less is known about the influence of impurities on such reactions. In this paper, the influence of nitrogen, introduced via ion implantation, is studied on the solid-state amorphization reaction of thin (35 nm) Ni films with Si, using in situ x-ray diffraction (XRD), ex situ Rutherford backscattering spectrometry, XTEM, and synchrotron XRD. It is shown that due to small amounts of nitrogen (<2 at.%), an amorphous Ni–Si phase grows almost an order of magnitude thicker during annealing than for unimplanted samples. Nitrogen hinders the nucleation of the first crystalline phases, leading to a new reaction path: the formation of the metal-rich crystalline silicides is suppressed in favour of an amorphous Ni–Si alloy; during a brief temperature window between 330 and 350 °C, the entire film is converted to an amorphous phase. The first crystalline structure to grow is the orthorhombic NiSi phase. We demonstrate that this impurity-enchanced solid-state amorphization reaction occurs only under specific implantation conditions. In particular, the initial distribution of nitrogen upon implantation is crucial: sufficient nitrogen impurities must be present at the interface throughout the reaction. Introducing implantation damage without nitrogen impurities (e.g. by implanting a noble gas) does not cause the enhanced solid-state amorphization reaction. Moreover, we show that the stabilizing effect of nitrogen on amorphous Ni–Si films (with a composition ranging from 40% to 50% Si) is not restricted to thin film reactions, but is a general feature of the Ni–Si system.

AFM, RBS and tribological properties of WC/WS2 nanostructures after 1.5 MeV Nb+ implantation

The purpose of this study was to evaluate the impact of Nb+ ion implantation in WC/WS2 nanostructures and their tribological properties. The films were deposited on silicon and stainless-steel substrates by DC and RF magnetron sputtering at 400 °C. Different concentrations for sputtering of the WC targets were used while the concentration for WS2 was maintained constant for all the deposition processes. Nb ion implantation with an energy of 1.5 MeV and a dose of 6 × 1014 ions/cm2 at room temperature was done at the 3 MV Tandetron™ accelerator from “Horia Hulubei” National Institute for Physics and Nuclear Engineering – IFIN-HH. The topography of the samples was analyzed by atomic force microscopy (AFM). Rutherford backscattering spectrometry (RBS) investigations gave information regarding stoichiometry and thicknesses of the coatings while tribological properties were studied using a pin–on–ball tribometer before and after Nb ion implantation. We have found that after the Nb implantation the values measured for the coefficient of friction were lower as compared to the unimplanted samples thought to be due to the discrete amorphization sites which could be produced at this lower fluence by energy deposition through elastic and inelastic collisions.

Eu–Mg defects and donor–acceptor pairs in GaN: photodissociation and the excitation transfer problem

We have investigated the temperature-dependent photoluminescence (TDPL) profiles of Eu3+ ions implanted in an HVPE-grown bulk GaN sample doped with Mg and of donor–acceptor pairs (DAP) involving the shallow Mg acceptor in GaN(Mg) (unimplanted) and GaN(Mg):Eu samples. Below 125 K, the TDPL of Eu3+ in GaN(Mg):Eu correlates with that of the DAP. Below 75 K, the intensity of Eu3+ emission saturates, indicating a limitation to the numbers of Eu–Mg defects available to receive excitation transferred from the host, while the DAP continues to increase, albeit more slowly in the implanted than the unimplanted sample. Prolonged exposure to UV light at low temperature results in the photodissociation of Eu–Mg defects in their Eu1(Mg) configuration, with a corresponding increase in shallow DAP emission and the emergence of emission from unassociated EuGa (Eu2) defects.

Globular chitosan treatment of bovine jugular veins: evidence of anticalcification efficacy in the subcutaneous rat model.

Vascular xenografts are widely used in cardiovascular surgery as an alternative to autologous vessels and vascular allografts. Calcification is one of the main drawbacks of vascular grafts, especially among young patients and children. Among different anticalcification approaches, chitosan emerges as a highly promising candidate due to its versatility, natural origin, and biocompatibility. We investigated the anticalcification efficacy of globular chitosan ("Chitozol") as it demonstrated the improved rate of water solubility as compared with conventional linear macromolecules of chitosan. In addition, we supposed that compact globular form of "Chitozol" molecules could provide effective penetration of extracellular matrix of bovine jugular veins (BJVs). Our results revealed that "Chitozol" treatment mitigated calcification in the experimental groups as compared to the control groups (without any treatment, conventional treatment with glutaraldehyde, and commercially available Contegra conduit). Different concentrations of "Chitozol" (0.3% and 3%), as well as different incubation times (15 and 30min), were equally effective in the prevention of calcification. In addition, "Chitozol" treatment with decellularization of BJVs demonstrated slightly improved stress-strain properties of unimplanted samples. Thus, the filling of fresh BJV with globular chitosan is proposed as a promising emerging treatment for the mitigation of calcific degeneration in BJVs xenografts.

Persistent photoconductivity in hydrogen ion-implanted KNbO3 bulk single crystal

Persistent Photoconductivity (PPC) in hydorogen-ion implanted (001) oriented KNbO3 bulk single crystals (perovskite structure at room temperature; ferroelectric with a band gap of 3.16 eV) is studied in air at room temperature to prevent the crystallinity degradation caused by the phase transition. Hydrogen is implanted into KNbO3 bulk single crystals using the energy (the peak ion fluence) of 500 keV (5.0 × 1015 cm-2). The resistivity varies from ∼108 Ω/□ for an un-implanted KNbO3 sample to 2.3 × 105 Ω/□ for as-implanted one. suggesting the presence of donors consisting of hydrogen interstitial and oxygen vacancy. The PPC is clearly observed with ultraviolet and blue LEDs illumination rather than green and infrared, suggesting the release of electrons from the metastable conductive state below the conduction band relating to the charge states of the oxygen vacancy as observed in electron irradiated ZnO.

Abstract 624: Accumulation of Advanced Glycation End Products is Associated With Structural Degeneration of Bioprosthetic Heart Valves

Introduction: Bioprosthetic heart valves (BHV) are widely used but frequently limited by structural valve degeneration (SVD), necessitating re-operation. Calcification is by far the best-studied SVD mechanism, but recent studies suggest that oxidative stress contributes to SVD. Advanced glycation end products (AGEs), formed by the ligation of sugar derivatives to proteins under oxidative conditions, mediate tissue degeneration in cardiovascular diseases. AGEs effect tissue damage through cross-linking and degradation of extracellular matrix proteins including collagen, a major structural component of BHV, as well as through exacerbation of inflammatory cell stimulation. Hypothesis: We hypothesize that AGEs accumulate in BHVs and are associated with oxidative stress-based SVD Methods: We performed immunohistochemistry for AGEs and specifically carboxymethyl lysine (CML) on sections of fixed, paraffin-embedded samples of degenerated bioprosthetic heart valves from 7 patients in the Penn Cardiac Bioregistry (4 male, 3 female, ages 40-83) and 4 short-term experimental Melody valve leaflets deployed in branch pulmonary arteries of 3 sheep. We correlated these results with levels of the circulating AGE receptor sRAGE via ELISA for patient BHV explants and with oxidized amino acid levels quantitated by mass spectrometry of di-tyrosine for experimental sheep BHV explants. Results: There was diffuse accumulation of AGEs in both clinical SVD and sheep explants of BHV. Immunohistochemistry reveals clear AGE and CML staining in all tested valves versus minimal to absent staining in unimplanted control samples. Staining intensity qualitatively correlated with overall di-tyrosine accumulation as well as sRAGE levels that were elevated in BHV patients. Notably, local staining for AGE in BHV is intensified in areas of calcification, thickening, and apparent inflammatory infiltration as well as in areas with structural damage. Conclusions: Extensive AGE accumulation was observed in both BHV explanted for SVD and sheep explants compared to controls, supporting the view that AGEs are associated with SVD pathophysiology. The association of AGE accumulation with di-tyrosine in BHV suggests that oxidative stress is a major mechanism of BHV SVD.

Effect of temperature on surface characteristics of nitrogen ion implanted biocompatible titanium.

It has been established that nitrogen implantation can modify metals surface properties such as corrosion, wear, friction, etc. Recent studies have shown that nitrogen implantation into titanium and its alloys leads to the formation of titanium nitride, which has interesting biological, chemical, and mechanical properties. In the present investigation, commercially pure biocompatible titanium implanted by nitrogen. Implantation of ions performed at 80 keV and a dose of 2.1 × 1018 ions/cm2 at four different temperatures of 300, 473, 673 and 873 k. Phase and chemical compositions of modified surfaces after implantation obtained using grazing incidence X-ray diffraction technique (GIXRD) and Fourier transform infrared spectrum (FTIR), respectively. The roughness variations before and after ion implantation were observed by atomic force microscopy (AFM). Electrochemical behavior of the samples was investigated in Ringer solution by using electrochemical impedance spectroscopy and polarization tests. Scanning electron microscopy micrographs was used to evaluate the surface morphology of the samples. Variation of the Young's modulus and hardness of samples were examined using nano-indentation technique before and after ion implantation. Compared to nano-hardness of unimplanted sample, the maximum nano-hardness value of implanted samples is as high as 14.2 GPa, which is at least eight times larger than hardness of the unimplanted sample. The elastic modulus of unimplanted sample was obtained 106 GPa and the maximum elastic modulus value of implanted samples is as high as 178 GPa. Corrosion test results showed that implantation could increase the corrosion resistance of samples, but by increasing the implantation temperature, the corrosion resistance will decrease.

Lattice displacement and electrical property of Li-ion implanted GaN single crystal

Ga and N lattice displacements in Li-ion implanted GaN are evaluated by Rutherford backscattering using proton beam. Li-ion implantation into GaN single crystal wafer with 450 μm in thickness is performed with energies of 50 keV (ion fluence; 2 x 1014 cm-2), 80 keV (3 x 1014 cm-2) and 120 keV (5 x 1014 cm-2) at room temperature. The aligned spectra are obtained from scattering along the <0001> channeling direction. The number of displaced Ga and N atoms estimated from χmin (the ratio between aligned and random) were 3.5 × 1020 cm-3 and 8.7 × 1020 cm-3, respectively. The displacement concentration of N atoms is larger than that of Ga atoms. This suggests that N interstitial (Ni) relating to the displacement of N atoms is introduced in Li-ion implanted GaN. This result is similar to that of the neutron irradiated GaN. The sheet resistance is 2.6 x 102 Ω/sq. for un-implanted samples and 1.3 x 103 Ω/sq. for Li-ion implanted ones. The origin of the high resistivity after the Li-ion implantation is mainly attributed to the carrier compensation effect due to the deep level of Ni. The resistance decreases to 1.1 x 102 Ω/sq. by annealing at 973 K for 20 min in N2 flow, suggesting the recovery of the implantation induced defects.

Impact of rapid thermal annealing on Mg-implanted GaN with a SiO x /AlN cap-layer

Local p-type doping in GaN is a key issue for device development but it remains a challenge to be achieved. In this work, we studied the activation of Mg implanted in the GaN. Multi-energy implantations were performed to achieve a “box-like” profile. SIMS measurements showed unexpected deep Mg profile due to defect-assisted channeling in the GaN. In addition, a high-density defect region induced by the implantation was evidenced by TEM characterization. To protect the GaN surface prior to high temperature annealing, an AlN cap-layer was deposited by reactive sputtering followed by SiOx deposition leading to a double cap-layer. Afterwards, the capped samples were RTA-annealed at high temperatures for several minutes under nitrogen. Two types of annealing processes were applied: a monocycle and a multicycle annealing. After annealing, the double cap-layer was etched using chemical solutions. AFM characterizations, after annealing and cap-layer etching, demonstrated that a GaN surface with similar roughness to as-grown samples and pit-free can be achieved after both monocycle and multicycle annealing steps. However, an AlGaN layer at the AlN/GaN interface is observed by ToF-SIMS and remained after the etching of the AlN layer. Finally, Schottky diodes were processed on the unimplanted and annealed samples, evidencing a double barrier, while P/N junction diodes are still being processed on the implanted and annealed samples.