E. Wendler

Ion-beam induced damage and annealing behaviour in SiC

Abstract The paper presents the damage accumulation in silicon carbide (SiC) as a function of the ion mass, the ion energy and the implantation temperature. A defect-interaction and amorphization model is used to analyse the dose dependence of defect production, as obtained by the various methods. The temperature dependence of the amorphization dose can be represented assuming a thermally enhanced annealing within the primary collision cascades. On the basis of such a model, a critical implantation temperature is obtained, which was found to vary with the ion mass and the implantation energy. The concurrent influence of implantation temperature and ion fluence on the resulting damage distribution in SiC is demonstrated. The damage annealing of ion implanted SiC is investigated for low, medium and high damage concentrations. The effect of the implantation temperature and the concentration of implanted atoms, both influencing the kind of defects obtained after implantation, on the annealing behaviour is analysed.

Damage formation and annealing at low temperatures in ion implanted ZnO

N, Ar, and Er ions were implanted into ZnO at 15 K within a large fluence range. The Rutherford backscattering technique in the channeling mode was used to study in situ the damage built-up in the Zn sublattice at 15 K. Several stages in the damage formation were observed. From the linear increase of the damage for low implantation fluences, an upper limit of the Zn displacement energy of 65 eV could be estimated for [0001] oriented ZnO. Annealing measurements below room temperature show a significant recovery of the lattice starting at temperatures between 80 and 130 K for a sample implanted with low Er fluence. Samples with higher damage levels do not reveal any damage recovery up to room temperature, pointing to the formation of stable defect complexes.

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

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.

Defect production during ion implantation of various AIIIBV semiconductors

The present paper gives a survey about the defect generation caused by ion implantation of GaAs, InAs, GaP, and InP. By combining Rutherford backscattering spectrometry, optical spectroscopy, and transmission electron microscopic methods, further information concerning the kinetics of the defect production as well as the type of defects created is obtained. Generally, the defect concentration in the region of implantation parameters investigated can be described by the energy density deposited into nuclear processes. Below critical values of the nuclear deposited energy density in GaAs weakly damaged layers containing point defects and point defect clusters are produced. With increasing nuclear deposited energy density an increasing number of amorphous zones is created due to manifold overlap of the initial defect clusters. The results indicate that in GaAs and InAs already at relatively low implantation temperatures, the amorphization occurs via homogeneous defect nucleation. The results obtained for GaP...

Growth of silicon nanowires by chemical vapour deposition on gold implanted silicon substrates

Silicon nanowires (SiNWs) were synthesized by the vapour–liquid–solid (VLS) growth mechanism using gold implanted silicon substrates. Implantation of high ion fluences leads to an amorphized silicon layer at the wafer surface. During annealing the Au in the implanted region agglomerates and yields Au droplets at the surface upon recrystallization of the amorphous layer. The structural quality of nanowires grown from implanted substrates is comparable to those grown on wafers with evaporated gold films. This opens up new possibilities for local growth of SiNWs by implanting through masks or using a focused ion beam technique.

Two-beam irradiation chamber for in situ ion-implantation and RBS at temperatures from 15 K to 300 K

In order to investigate the primary eAects of ion‐solid interaction, low-temperature implantation and measurement of the irradiated samples without warming up are necessary. A corresponding experimental setup is described, which allows one to perform ion-implantation at constant temperatures between 15 K and 300 K and the defect analysis by Rutherford backscattering spectrometry (RBS) without changing the target temperature. 200 keV Ar a implants into GaAs are done at 15 K and RBS spectra are collected with the detector placed under a backscattering angle of 110∞. Under these conditions a very good agreement of the measured defect profiles with those calculated with the TRIM code is obtained. The defect profiles were calculated from the RBS spectra with due consideration for the lattice vibrations. The Debye temperatures of GaAs at diAerent temperatures are thus determined. ” 2001 Elsevier Science B.V. All rights reserved.

Ion mass and temperature dependence of damage production in ion implanted InP

Ion beam induced damaging and amorphization of crystalline InP is investigated. 100 keV B+, 300 keV Si+, 200 keV Ar+ and 600 keV Se+ ions are implanted into 〈100〉 InP at temperatures ranging from 80 K to 420 K. The implanted layers are analyzed using Rutherford backscattering spectrometry in channeling configuration, cross section transmission electron microscopy and optical spectroscopy in the sub-gap frequency region. The temperature dependence of damage production can be represented assuming a thermally stimulated defect diffusion within the primary collision cascades, resulting in a shrinkage of the remaining defect clusters. At a critical temperature T∞ these clusters dissolve completely and only point defect complexes nucleate. Then, amorphization occurs only at very large ion fluences (≈1016cm−2) and the process seems to be influenced by the high amount of implanted ions. A defect band forms around the projected range of the implanted ions, which may act as a diffusion barrier for point defects. Th...

Defect production during ion implantation of various A/sub III/B/sub V/ semiconductors

The present paper gives a survey about the defect generation caused by ion implantation of GaAs, InAs, GaP, and InP. By combining Rutherford backscattering spectrometry, optical spectroscopy, and transmission electron microscopic methods, further information concerning the kinetics of the defect production as well as the type of defects created is obtained. Generally, the defect concentration in the region of implantation parameters investigated can be described by the energy density deposited into nuclear processes. Below critical values of the nuclear deposited energy density in GaAs weakly damaged layers containing point defects and point defect clusters are produced. With increasing nuclear deposited energy density an increasing number of amorphous zones is created due to manifold overlap of the initial defect clusters. The results indicate that in GaAs and InAs already at relatively low implantation temperatures, the amorphization occurs via homogeneous defect nucleation. The results obtained for GaP...

Comparative study of damage production in ion implanted III–V-compounds at temperatures from 20 to 420 K

Abstract The damage evolution in ion implanted InP, GaAs, GaP and InAs is studied as a function of the ion fluence in the temperature range 20–420 K using various ion masses. It is shown that the macroscopic behaviour can be described in terms of critical temperatures T c which depend on the ion mass and on the dose rate for a given material. At temperatures T I T c amorphization is obtained by direct impact amorphization and the growing of the amorphous zones. However, athermal in-cascade annealing is observed even at 20 K, which is the more pronounced the lighter the ion is. This indicates the influence of the density of the primary cascades on defect recombination. Around T c intrinsic defects are mobile leading to an equilibrium between defect production and annealing over a broad dose region. Amorphization at very large ion fluences is the consequence of complex processes which are influenced by the high ion concentration and the formation of dislocation bands near the end of range. Using an empirical formula which describes the ion mass and dose rate dependence of the critical temperature, the damage evolution for certain implantation conditions becomes predictable.

High temperature ion implantation of silicon carbide

Abstract The damage production in 6H-SiC has been investigated for Ga and Sb implantation in the temperature region between 80 K and 1473 K. For this purpose a high temperature sample holder has been developed. For implantation temperatures above 573 K amorphization is avoided even at high ion fluences. The decrease of the defect density with the temperature is accompanied by a shift of the distribution towards the depth indicating a change of the nature of the defects. To obtain minimum damage implantation temperatures higher than ≈ 1200 K are necessary. The reduction of the damage concentration at higher temperatures is accompanied by a substitutional incorporation of part of the implanted ions, at 700 K 70% of the implanted Sb atoms are incorporated.