P. Lévêque

Separation of vacancy and interstitial depth profiles in ion-implanted silicon: Experimental observation

Financial support was kindly provided by the Swedish Research Council for Engineering Sciences (TFR), the Swedish Foundation for International Cooperation in Research and Higher Education (STINT), and the EU Commission, Contract No. ERBFMRXCT980208 (ENDEASD—TMR network).

Vacancy and interstitial depth profiles in ion-implanted silicon

The authors gratefully acknowledge support from the European Commission TMR Program, network Contract No. ERBFMRXCT 980228. Partial financial support was also received from the Swedish Research Council for Engineering Science (TFR) and the Swedish Foundation for International Cooperation in Research and Higher Education (STINT).

An investigation on the modeling of transient enhanced diffusion of ultralow energy implanted boron in silicon

We have investigated and modeled the B diffusion in Si following ultralow energy implantation. Secondary ion mass spectrometry measurements revealed that B diffusion is transient enhanced. For the simulation we have used a kick-out model which requires only two uncorrelated parameters able to describe the microscopical processes involved. By optimizing the parameters, an excellent agreement between the simulated and the experimental profile broadening is achieved. Moreover, an extension of the previous model that accounts for interstitial cluster formation and dissolution was implemented in order to achieve a better description of B diffusion. The extracted parameters are discussed and compared with published values.

Bistable defect in mega-electron-volt proton implanted 4H silicon carbide

Epitaxial 4H-SiC n-type layers implanted at room temperature with a low fluence of mega-electron-volt protons have been measured by deep level transient spectroscopy (DLTS). The proton fluence of 1 ...

Hydrogen-related defect centers in float-zone and epitaxial n-type proton implanted silicon

Abstract Hydrogen-related defects in float zone (Fz) and epitaxial (Epi) n-type silicon crystals have been studied by means of deep level transient spectroscopy. These defects, as well as the characteristic vacancy-oxygen (VO) and divacancy (V 2 ) centers were introduced by proton implantation (1.3 MeV) using a dose of 1×10 10 /cm 2 . A hydrogen-related defect level located at 0.45 eV below the conduction band edge ( E c ) appears in both kind of samples. Another hydrogen-related defect appears predominantly in the Fz samples with a level at E c −0.32 eV. Depth profiling as well as annealing studies strongly suggest that the level at E c −0.45 eV is due to a complex involving hydrogen and V 2 . The level at E c −0.32 eV is strongly suppressed in the high purity Epi samples and the same holds for VO center. These results together with annealing data provide substantial evidence that the E c −0.32 eV level originates from a VO-center partly saturated with hydrogen (a VOH complex). Finally, in the Epi samples a new level at ∼ E c −0.31 eV is resolved, which exhibits a concentration versus depth profile strongly confined to the damage peak region. The origin of this level is not known but the extremely narrow depth profile may indicate a higher-order defect of either vacancy or interstitial type.

Dose-rate influence on the defect production in MeV proton-implanted float-zone and epitaxial n-type silicon

Abstract The production of stable vacancy-related point defects in proton-implanted float-zone and epitaxial silicon has been studied in the low dose range (⩽10 10 /cm 2 ) as a function of dose-rate. The well-known “inverse dose-rate” effect has been observed in both types of materials with a decrease in the concentration of vacancy-related defects as the dose-rate increases. The effect is less pronounced in oxygen lean epitaxial silicon. Moreover, a continuous decrease of the vacancy-related defect concentration as a function of the flux was measured while a threshold was expected according to previous studies. Both of these results can be explained by a simple calculation, taking into account the influence of the oxygen concentration as well as the influence of the diffusion coefficient of point defects on the “inverse dose-rate” effect.

Defect Evolution in Proton-Irradiated 4H SiC Investigated by Deep Level Transient Spectroscopy

In this contribution we report on the defect formation and annealing of 4H SiC ntype epilayers implanted at room temperature with low fluence of MeV protons. The high energy protons will penetrate the entire epi layer and create an almost constant concentration of point defects. The fluence used is 1×10 12 cm, which will create a concentration of primary silicon or carbon interstitials in the order of 1×10 14 cm. Most of the primary defects will recombine, but a substantial fraction will survive or form more stabl e defect complexes. These secondary defects are probed by deep level transient spectr o copy (DLTS) in the temperature interval of 77 to 340 K.

Influence of boron on radiation enhanced diffusion of antimony in delta-doped silicon

The silicon samples used in this work contain a sequence of alternating boron and antimony spikes grown by molecular beam epitaxy. These samples were irradiated with 2.5 MeV protons at elevated temperatures ranging from 580 °C to 830 °C and characterized by secondary-ion mass spectrometry. The energy of the proton beam was chosen such that the generation rate of point defects can be considered as uniform throughout the delta-doped layers. For each sample the boron and the antimony diffusion coefficient are increased under irradiation as compared to their diffusivity in unirradiated areas. A measurable diffusion of antimony is observed in samples containing both boron and antimony spikes even at temperatures as low as 580 °C while a reference sample containing only an antimony spike do not exhibit any radiation enhanced diffusion, even at 830 °C. The boron diffusion coefficient increases as the irradiation temperature increases but the antimony diffusion coefficient decreases for the highest irradiation te...

Irradiation enhanced diffusion of boron in delta-doped silicon

Two kinds of silicon samples have been used in this work: one containing a sequence of boron spikes and one with a sequence of alternating boron and antimony spikes, both grown by molecular beam epitaxy. These samples were irradiated with 2.5 MeV protons at an elevated temperature ranging from 500 to 830 °C and characterized by secondary-ion-mass spectrometry. The energy of the proton beam was chosen such that the generation rate of point defects can be considered as uniform throughout the delta-doped Si samples. The influence of the sample surface and of the boron concentration (ranging from 5×1015 to 3.2×1018 B/cm3 in the different samples) on the diffusion of boron have been studied in detail. The effect of antimony on boron diffusion has also been analyzed. For each sample, the B diffusion coefficient is increased under irradiation as compared to the B diffusion coefficient in unirradiated areas. This enhancement is dependent on the irradiation temperature, on the position of the boron spike and on th...

Separation of vacancy and interstitial depth profiles in proton- and boron-implanted silicon

Anew experimental method of studying shifts between concentration-versus-depth profiles of vacancy-type and interstitial-type defects in ion-implanted silicon is demonstrated. The concept is based on deep level transient spectroscopy (DLTS) measurements utilizing the filling pulse variation technique. The vacancy profile, represented by the vacancy-oxygen center and the interstitial profile, represented by the substitutional carbon-interstitial carbon pair, are obtained at the same sample temperature by varying the duration of the filling pulse. Thus the two profiles can be recorded with a high relative depth resolution. Point defects have been introduced in low doped float zone n-type silicon by implantation with 6 MeV boron ions and 1.3 MeV protons at room temperature, using low doses. For each implantation condition the peak of the interstitial profile is shown to be displaced by � 0:5 lm towards larger depths compared to that of the vacancy profile. This shift is primarily attributed to the preferential forward momentum of recoiling Si atoms, in accordance with theoretical predictions. 2002 Elsevier Science B.V. All rights reserved.