Annealing Of Divacancies Research Articles

Dark Current Spectroscopy of Irradiated CCD Image Sensors

Dark current spectroscopy is used to directly investigate deep-level traps induced by alpha particle irradiation in charge-coupled devices, at trap concentrations as low as ~2 times 107 cm-3. The irradiated devices have long dark current histogram tails that are quantized at long imager integration times. This quantization is due to the discrete nature of the distribution of the radiation-induced traps within the device pixels. Four distinct traps, with different dark current generation rates, are found and characterized in terms of their activation energies and capture cross-sections. Two of the traps, identified as the divacancy and the E-center (phosphorus-vacancy), have the highest concentrations and generation rates and are the main constituents of the irradiation tails. The origin of these irradiation tails is explained as a superposition of peaks formed by pixels that contain from a single deep-level trap to multiple traps of the same or different types. Divacancy annealing is shown to result in the formation of four additional traps, which are tentatively attributed to vacancy-oxygen, vacancy-hydrogen, and high-order silicon-vacancy complexes.

Special features of annealing of radiation defects in irradiated p-Si crystals

p-Si single crystals grown by the Czochralski method were studied; the hole concentration in these crystals was p = 6 × 1013 cm−3. The samples were irradiated with 8-MeV electrons at 300 K and were then annealed isochronously in the temperature range T ann = 100–500°C. The studies were carried out using the Hall method in the temperature range of 77–300 K. It is shown that annealing of divacancies occurs via their transformation into the B s V 2 complexes. This complex introduces the energy level located at E v + 0.22 eV into the band gap and is annealed out in the temperature range of 360–440°C. It is assumed that defects with the level E v + 0.2 eV that anneal out in the temperature range T ann = 340–450°C are multicomponent complexes and contain the atoms of the doping and background impurities.

Kinetics of divacancy annealing and divacancy-oxygen formation in oxygen-enriched high-purity silicon

In this work the thermal kinetics of the transformation from the divacancy $({\mathrm{V}}_{2})$ to the divacancy-oxygen $({\mathrm{V}}_{2}\mathrm{O})$ complex has been studied in detail, and activation energies, $({E}_{a})$, have been obtained. Diffusion oxygenated float-zone silicon (DOFZ-Si) samples of $n$-type with a doping of $5\ifmmode\times\else\texttimes\fi{}{10}^{12}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$ and oxygen content of $(2--3)\ifmmode\times\else\texttimes\fi{}{10}^{17}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$ have been irradiated with $15\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}$ electrons. Isothermal annealing studies of electrically active defects have been performed by means of deep-level transient spectroscopy. Heat treatments at temperatures in the range $205\phantom{\rule{0.2em}{0ex}}\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}--285\phantom{\rule{0.2em}{0ex}}\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ have all shown a shift in the singly negative and doubly negative divacancy levels, due to the annealing of ${\mathrm{V}}_{2}$ and the formation of ${\mathrm{V}}_{2}\mathrm{O}$. By studying the temperature-dependent rate of this process which exhibits first order kinetics, it has been found that both the annealing ${\mathrm{V}}_{2}$ and the formation of ${\mathrm{V}}_{2}\mathrm{O}$ have activation energies of $\ensuremath{\approx}1.3\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. This value is ascribed to migration of ${\mathrm{V}}_{2}$, and the results favor strongly a model where ${\mathrm{V}}_{2}$ is trapped by interstitial oxygen atoms during migration. In addition, the process takes place with a high efficiency since the loss of ${\mathrm{V}}_{2}$ and the growth of ${\mathrm{V}}_{2}\mathrm{O}$ display a close one-to-one proportionality. Finally, it has been found that the diffusivity pre-exponential factor, ${D}_{{\mathrm{V}}_{2}}^{0}$, for ${\mathrm{V}}_{2}$ is in the range $3\ifmmode\pm\else\textpm\fi{}1.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{2}∕\mathrm{s}$, which agrees well with a simple theoretical model of ${\mathrm{V}}_{2}$ diffusion in Si.

Defects in FZ-silicon after neutron irradiation—A positron annihilation and photoluminescence study

Float-zone (FZ) Si irradiated with 1 MeV neutrons was investigated by means of positron annihilation lifetime spectroscopy and photoluminescence. Three types of defects were observed: di-vacancies, small vacancy clusters and an unknown defect with the defect-related lifetime of (285 ± 5) ps that contribute to positron trapping only at low temperatures. Two annealing stages were observed: one at 350°C and another at 500°C. While the former is due to the annealing of divacancies, the latter is caused by the annealing of vacancy clusters and the unknown defect.

Divacancies in proton irradiated silicon: variation of ESR signal with annealing time

Annealing of divacancies in 8MeV proton-irradiated silicon was investigated using electron paramagnetic resonance (EPR). This paper presents the results for annealing at 160°C for up to 600min and for one sample annealed at 250°C. The EPR signal shows a clear evolution with annealing time for annealing at 160°C. Annealing for 40min at 250°C, yields almost the same EPR signal as for a 600min anneal at 160°C, but with a lowered intensity. In the light of previous results, the EPR behaviour substantiate the presence of two distinct annealing stages for defects in proton-irradiated silicon.

Formation of a double acceptor center during divacancy annealing in low-doped high-purity oxygenated Si

Deep-level transient spectroscopy studies of electronic defect levels in 7-MeV proton-irradiated n-type float-zone Si with a doping of $(3--5)\ifmmode\times\else\texttimes\fi{}{10}^{12}{\mathrm{cm}}^{\ensuremath{-}3}$ and oxygen content of $\ensuremath{\sim}{10}^{16}--{10}^{17}{\mathrm{cm}}^{\ensuremath{-}3}$ have been performed. The thermal stability of the irradiation-induced defects has been investigated for temperatures up to 400 \ifmmode^\circ\else\textdegree\fi{}C. It has been found that annealing of the divacancy-related levels, the singly negative, ${V}_{2}(0/\ensuremath{-}),$ and the doubly negative, ${V}_{2}(\ensuremath{-}/=),$ charge states at 220--300 \ifmmode^\circ\else\textdegree\fi{}C results in the formation of a new center with singly negative, $X(0/\ensuremath{-}),$ and doubly negative, $X(\ensuremath{-}/=),$ charge states. The new center anneals out at 325--350 \ifmmode^\circ\else\textdegree\fi{}C during isochronal treatment for 15 min. The capture kinetics studies reveal that the electron capture cross section of $X(0/\ensuremath{-})$ is larger than that of ${V}_{2}(0/\ensuremath{-})$ while the capture cross section of $X(\ensuremath{-}/=)$ is close to that of ${V}_{2}(\ensuremath{-}/=).$ The transformation of ${V}_{2}(0/\ensuremath{-})$ and ${V}_{2}(\ensuremath{-}/=)$ into $X(0/\ensuremath{-})$ and $X(\ensuremath{-}/=)$ is very efficient with only a small loss in the peak amplitudes, and the position of the energy levels are close to those of ${V}_{2}.$ Hence, it is tempting to suggest that the atomic configuration of the X center is closely related to that of ${V}_{2},$ and a possible identification of X may be the divacancy-oxygen center ${(V}_{2}\mathrm{O}).$

Divacancies in proton irradiated silicon: characterization and annealing mechanisms

Annealing of divacancies produced by ion bombardment of crystalline silicon has been characterized using differential scanning calorimetry (DSC) and Fourier transform infrared absorption (FTIR). DSC at a rate of 40°C/min shows two clear peaks in the heat release, one at 140°C and the other at 240°C. The activation energies of these peaks were calculated assuming first order kinetics and found to be approximately 1.2 and 1.5 eV. The remaining fraction of divacancies with respect to annealing temperature was measured by FTIR and compared to the remaining fraction of defects calculated from the heat released in DSC. Annealing measurements are in agreement with previous work on electron and neutron irradiation of Si despite much higher defect concentrations.

An annealing study of defects induced by electron irradiation of Czochralski-grown Si using a positron lifetime technique

Annealing processes of defects induced by 3 MeV electron irradiation in Czochralski-grown Si were studied by means of positron lifetime measurements. Several annealing processes were identified from a comparison with previous EPR results. The activation energies were also determined from an analysis of isothermal annealing. The results are summarized as follows. Divacancies (V 2s) disappear around 250°C to form divacancy + oxygen (V 2O) complexes. The activation energy for the annealing of divacancies is determined to be 1.30 eV. The V 2O complexes disappear at around 400°C to form trivacancy + oxygen (V 3O) and divacancy + dioxygen (V 2O 2) complexes. The activation energy for the annealing of V 2O complexes is determined to be 2.14 eV. The V 3O and V 2O 2 complexes disappear at around 440°C to form trivacancy-dioxygen (V 3O 2) complexes. The activation energy for the annealings of these defects is determined to be 2.23 eV. The V 3O 2 complexes disappear at around 475°C. The activation energy is determined to be 2.56 eV. The annealing processes of divacancies, vacancy + oxygen (VO) and vacancy + dioxygen (VO 2) complexes were also examined from measurement of their infrared absorption. Temperature dependent changes of the absorption coefficient due to divacancies are in good agreement with temperature dependent changes of the positron trapping rate due to divacancies. Positron trapping at VO and VO 2 complexes was not detected, in contrast to the measurement of optical absorption.

Divacancy Annealing in Silicon Monitored by Differential Calorimetry and Infrared Absorption Spectroscopy

ABSTRACTAnnealing of divacancies in crystalline Si has been characterized by differential scanning and isothermal calorimetry and infrared absorption spectroscopy. Si discs of 0.1 mm thickness have been implanted with 3.4 MeV protons. Scanning calorimetry shows a relatively sharp peak centered around 425 K and a broader feature ranging from 450 to 620 K. The isothermal heat release at 620 K exhibits a single exponential rather than a bimolecular decay. As the annealing progresses, a decrease in infrared absorption at 1.8 µm is observed which is directly related to the annealing of divacancies.

Recharging and Negative Annealing of Divacancies in Neutron-Irradiated Silicon

physica status solidi (a)Volume 111, Issue 2 p. K141-K144 Short Note Recharging and Negative Annealing of Divacancies in Neutron-Irradiated Silicon V. V. Petrov, V. V. Petrov Department of Physics, Belorussian State University, Minsk Search for more papers by this authorV. V. Chornyi, V. V. Chornyi Department of Physics, Belorussian State University, Minsk Search for more papers by this author V. V. Petrov, V. V. Petrov Department of Physics, Belorussian State University, Minsk Search for more papers by this authorV. V. Chornyi, V. V. Chornyi Department of Physics, Belorussian State University, Minsk Search for more papers by this author First published: 16 February 1989 https://doi.org/10.1002/pssa.2211110238 Prospekt Lenina 4, SU-220080 Minsk, USSR. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Volume111, Issue216 February 1989Pages K141-K144 RelatedInformation

Peculiarities of divacancy annealing in radiation defect clusters

Abstract The annealing mechanism of divacancies involved in radiation defect clusters is suggested in accordance with which the interaction of interstitial carbon atoms and intrinsic diinterstitials, mobile at T≳ 100°C, with divacancies results in their smooth annealing in a wide temperature range.

Divacancy Annealing in Crystalline Silicon Using E-Beam and Pulsed Ruby Laser Excitation

ABSTRACTAnnealing of divacancies which were produced by 11B ion implantation was investigated under furnace, pulsed e-beam and pulsed ruby laser exposures. Despite orders of magnitude shorter exposure times for annealing and the concomitant expected high levels of electronic excitation and layer stress, we find that the thermal annealing mechanism observed for furnace annealing is an adequate description for divacancy annealing under e-beam exposure. The observed need for melting to remove divacancies by Q-switched laser annealing is also consistent with predictions based upon extrapolations from furnace annealing.

Amorphization of silicon by ion implantation: Homogeneous or heterogeneous nucleation?

Abstract The importance of homogeneous and heterogeneous nucleation in the amorphization of silicon by ion implantation is considered. Previously a homogeneous model involving dose rate had been used to identify neutral vacancy and divacancy annealing as important mechanisms in the amorphization process. In an attempt to verify this dose rate model, experiments which detect the electron spin resonance signal from the amorphous regions have been performed. Both a light ion (N+) and a heavy ion (Kr+) at low (20 keV) and high (180 keV) energy were implanted into silicon at low (80°K) and higher (∼350°K) temperatures. No dose rate dependence was found, and the temperature dependence is not as predicted by the model. In addition, the production rate is not proportional to the dose to the one-half power-a power dependence which has previously been attributed to homogeneous nucleation. Furthermore, since the data agrees with the predictions of a heterogeneous model, it is concluded that homogeneous nucleation is not an important process in the amorphization of silicon by ion implantation.

DIRECT EVIDENCE OF DIVACANCY FORMATION IN SILICON BY ION IMPLANTATION

The production of divacancies in Si by 400-keV oxygen ion implantation (ΦI = 1.75 × 1014 cm−2, two sides) was detected by the characteristic divacancy optical absorption band at 1.8 μ. This band has been previously correlated with the presence of divacancies in electron- and neutron-irradiated silicon. Ion-produced divacancy annealing near 200°C was observed to correlate with neutron-produced divacancy annealing. Detailed comparisons of the annealing of electron-, neutron-, and ion-produced divacancies suggest that the ion-produced divacancies anneal primarily in regions with sink concentrations ≥ 1019 cm−3.

Characteristics of Neutron Damage in Silicon

The production and annealing behavior of the divacancy and the $A$ center in fission-neutron-irradiated silicon was studied by infrared absorption, using the 1.8-, 3.9-, and 12-\ensuremath{\mu} bands. The production rate of the divacancy was found to be high, about 5.7 ${\mathrm{cm}}^{\ensuremath{-}1}$, and to be enhanced by the presence of boron (\ensuremath{\sim}2\ifmmode\times\else\texttimes\fi{}${10}^{17}$ atoms per ${\mathrm{cm}}^{3}$), but not by the presence of oxygen (\ensuremath{\sim}1\ifmmode\times\else\texttimes\fi{}${10}^{18}$ atoms per ${\mathrm{cm}}^{3}$). The annealing of divacancies in neutron-irradiated Si required an activation energy of 1.25 eV, as in electron-irradiated Si, indicating that most of the divacancies were removed by diffusion to sinks. The annealing results also indicate that the local defect concentrations in the damaged regions can be as high as \ensuremath{\sim}${10}^{20}$ defects ${\mathrm{cm}}^{\ensuremath{-}3}$, in which the divacancies still retain their individual properties as far as their infrared absorption and annealing properties are concerned. The production rate of the $A$ center was found to be extremely low. The near-edge absorption band was also studied. About 95% of the near-edge band disappeared upon annealing in the same broad temperature range as did the divacancies. From these results, it was concluded that the majority of the total volume in localized damage regions produced by the fission-neutron irradiation of silicon is rich in divacancies and is still crystalline.

Electrical Studies of Electron-Irradiatedn-Type Si: Impurity and Irradiation-Temperature Dependence

Electrical-conductivity and Hall-coefficient measurements have been used to investigate the crystal growth and irradiation-temperature dependence of the introduction and annealing of defects in electron-irradiated $n$-type silicon. Irradiations of 10-\ensuremath{\Omega} cm, phosphorus-doped silicon with 1.7-MeV electrons were performed at controlled temperatures between 75 and 300\ifmmode^\circ\else\textdegree\fi{}K, and isochronal annealing was investigated between 80 and 700\ifmmode^\circ\else\textdegree\fi{}K. Both intrinsic defects and impurity-associated defects are observed. The impurity independence of annealing between 100 and 200\ifmmode^\circ\else\textdegree\fi{}K suggests the annealing of intrinsic defects. The introduction rate for these intrinsic defects is independent of the irradiation temperature between 75 and 100\ifmmode^\circ\else\textdegree\fi{}K. The introduction rates for the impurity-associated defects, however, exhibit an exponential dependence on the reciprocal irradiation temperature between 75 and 100\ifmmode^\circ\else\textdegree\fi{}K consistent with a model based on metastable vancacy-interstitial pairs that predicts a temperature-dependent probability for vacancy-interstitial dissociation during irradiation and subsequent trapping by crystal impurities. For irradiations above 100\ifmmode^\circ\else\textdegree\fi{}K, the introduction rates of impurity-associated defects are relatively independent of the irradiation temperature. Excluding the carrier-removal annealing which is associated with the intrinsic-defect stage, 90% of the annealing in crucible-grown silicon and \ensuremath{\sim}70% of the annealing in float-zone, Dash, and Lopex silicon correlate with the annealing of the divacancy and impurity-associated defects observed in EPR and optical-absorption studies on $n$-type silicon. In crucible-grown silicon, the annealing temperatures of the dominant electrically active, impurity-associated defects correlate with those for the $A$ center and other oxygen-associated defects. Measurements of carrier concentration versus temperature provide additional evidence for the dominance of the $A$ center which has an energy level near ${E}_{c}\ensuremath{-}0.185$ eV, where ${E}_{c}$ is the energy of the conduction-band minimum. A level near ${E}_{c}\ensuremath{-}0.13$ eV also is observed in crucible-grown silicon for the oxygen-associated defects responsible for reverse annealing between 200 and 250\ifmmode^\circ\else\textdegree\fi{}K. In float-zone silicon, the annealing temperatures of the dominant electrically active defects correlate with the $E$-center and divacancy annealing. Lopex silicon is very similar to Dash silicon, and in these materials all the annealing stages of crucible and float-zone silicon are observed.