Defect Centers In Silicon Research Articles

Effect of localization on photoluminescence and zero-field splitting of silicon color centers

The study of defect centers in silicon has been recently reinvigorated by their potential applications in optical quantum information processing. A number of silicon defect centers emit single photons in the telecommunication $O$-band, making them promising building blocks for quantum networks between computing nodes. The two-carbon G-center, self-interstitial W-center, and spin-$1/2$ T-center are the most intensively studied silicon defect centers, yet despite this, there is no consensus on the precise configurations of defect atoms in these centers, and their electronic structures remain ambiguous. Here we employ ab initio density functional theory to characterize these defect centers, providing insight into the relaxed structures, band structures, and photoluminescence spectra, which are compared to experimental results. Motivation is provided for how these properties are intimately related to the localization of electronic states in the defect centers. In particular, we present the calculation of the zero-field splitting for the excited triplet state of the G-center defect as the structure is linearly interpolated from the A-configuration to the B-configuration, showing a sudden increase in the magnitude of the ${D}_{zz}$ component of the zero-field-splitting tensor. By performing projections onto the local orbital states of the defect, we analyze this transition in terms of the symmetry and bonding character of the G-center defect, which sheds light on its potential application as a spin-photon interface.

Determining the defect parameters of the deep aluminum-related defect center in silicon

Through a combined application of two characterization methods, deep-level transient spectroscopy and lifetime spectroscopy, the lifetime-limiting defect level in intentionally aluminum-contaminated Czochralski silicon has been analyzed and a complete set of defect parameters could be obtained. This aluminum-related defect center is found to be located at an energy level of Et−EV=0.44±0.02eV and exhibits an asymmetric capture cross section, with σp=3.6×10−13cm2 and σn=3.1×10−10cm2 being the hole and electron capture cross sections, respectively. The investigated defect center is attributed to the aluminum-oxygen complex (Al–O).

Interactions of hydrogen molecules with bond-centered interstitial oxygen and another defect center in silicon

Infrared spectra obtained from Czochralski (CZ) silicon heated in the range $1100l~Tl~1300\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ in ${\mathrm{H}}_{2},$ ${\mathrm{D}}_{2},$ or mixtures of the two gases, show vibrational absorption at $1075{\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ due to perturbed bond-centered interstitial oxygen atoms ${\mathrm{O}}_{i}.$ Deconvolutions of these absorption profiles imply that the observed perturbations to the ${\mathrm{O}}_{i}$ atom are due to adjacent defects incorporating two H atoms. This interpretation is confirmed by detection of modes ${\ensuremath{\nu}}_{1}$ $({\mathrm{\ensuremath{\nu}}}_{1\mathrm{H}\mathrm{H}}{,\mathrm{\ensuremath{\nu}}}_{1\mathrm{H}\mathrm{D}}{,\mathrm{\ensuremath{\nu}}}_{1\mathrm{D}\mathrm{D}})$ with ${\ensuremath{\nu}}_{1\mathrm{H}\mathrm{H}}{=3789\mathrm{}\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ and ${\ensuremath{\nu}}_{2}$ $({\mathrm{\ensuremath{\nu}}}_{2\mathrm{H}\mathrm{H}}{,\mathrm{\ensuremath{\nu}}}_{2\mathrm{H}\mathrm{D}}{,\mathrm{\ensuremath{\nu}}}_{2\mathrm{D}\mathrm{D}})$ with ${\ensuremath{\nu}}_{2\mathrm{H}\mathrm{H}}{=3731\mathrm{}\mathrm{cm}}^{\mathrm{\ensuremath{-}}1},$ that both correlate in strength with that of the $1075{\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ absorption. A third set of modes ${\ensuremath{\nu}}_{3}$ $({\mathrm{\ensuremath{\nu}}}_{3\mathrm{H}\mathrm{H}}{,\mathrm{\ensuremath{\nu}}}_{3\mathrm{H}\mathrm{D}}{,\mathrm{\ensuremath{\nu}}}_{3\mathrm{D}\mathrm{D}}),$ with ${\ensuremath{\nu}}_{3\mathrm{H}\mathrm{H}}{=3618\mathrm{}\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ detected in heat-treated CZ and float zone silicon and not related to the absorption at $1075{\mathrm{cm}}^{\mathrm{\ensuremath{-}}1},$ must be due to H-H pair defects trapped at an unknown impurity or lattice defect. The frequencies of the ${\ensuremath{\nu}}_{1\mathrm{H}\mathrm{D}},$ ${\ensuremath{\nu}}_{2\mathrm{H}\mathrm{D}},$ and ${\ensuremath{\nu}}_{3\mathrm{H}\mathrm{D}}$ modes imply that the three defects are ${\mathrm{H}}_{2}$ molecules with weakened bonds and small dipole moments resulting from interactions with either adjacent oxygen atoms $({\ensuremath{\nu}}_{1},{\ensuremath{\nu}}_{2})$ or a second type of trap $({\ensuremath{\nu}}_{3}).$ Annealing treatments imply that isolated ${\mathrm{O}}_{i}\ensuremath{-}{\mathrm{H}}_{2}$ complexes can dissociate for $Tg~70\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ allowing interstitial ${\mathrm{H}}_{2}$ molecules to diffuse away but they can be retrapped during a subsequent anneal at $Tl~50\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}.$

Hydrogenation of lithium- and calcium-related defect centers in silicon

Hydrogenation of lithium- and calcium-related defect centers in silicon

Electrical and Optical Characterization of Magnesium- and Calcium-Related Defect Centers in Silicon

Electrical and Optical Characterization of Magnesium- and Calcium-Related Defect Centers in Silicon

Processing Effects on the Electrical and Optical Properties of Sulfur-Related Defect Centers in Silicon and Similarities to the Oxygen Donor

ABSTRACTThe properties of sulfur-related defects in silicon are shown to differ dramatically from those that would have been expected on the basis of effective mass theory for a simple substitutional double donor. The ratio of the densities of the sulfur states as measured by capacitance-voltage techniques has been observed to vary in specimens fabricated from the same starting resistivity. Optical absorption studies have shown that the deepest sulfur level has a manifold of ground states which anneal at unequal rates at 550°C. Deep-level measurements show that the thermal emission rate at a given temperature and the variety of effects produced depends on annealing history and total sulfur density. The variability of properties of samples of sulfur-doped silicon is similar to those found for the oxygen donors in silicon, thus suggesting a chemical trend for the column VI impurities in silicon.

Defect centers in silicon produced by room temperature electron irradiation. III. Hall coefficient studies

The results of Hall coefficient and resistivity studies versus temperature on n-type high resistivity, electron-irradiated silicon are presented. When these results are considered in conjunction with parallel studies of photoconductivity and thermally stimulated current measurements made on the same group of samples, it is possible to propose a consistent model for the defect concentration and energy level distribution. Computed electron concentrations, and their variation with temperature are in good agreement with the experimental results. Levels computed from electrical studies are assigned to the neutral state of the divacancy, and to a center tentatively identified as the K-center. Nous donnons les resultats des etudes sur le coefficient de Hall et sur la resistivite en fonction de la temperature sur du silicium du type N de forte resistivite et irradie par les electrons. Quand on considere ces resultats avec ceux obtenus sur l'absorption optique, sur la photoconductivite et sur le courant dǔ a la stimulation thermique (TSC) sur la meme serie d'enchantillon, il est possible d'obtenir une modele pour la concentration des defaults et la distribution des niveaux d'energie. Les concentrations d'electrons calcules, et leur variation avec temperature sont en bon accord avec les resultats experimentaux. Les niveaux calcules a partir des etudes electriques sont associes avec l'etat neutre du “divacancy”, et un centre provisoirment identifie comme le “K-centre”.

Defect centers in silicon produced by room temperature electron irradiation. II. Thermally stimulated conductivity studies

The results of thermally stimulated conductivity (TSC) studies on high resistivity, oxygen free, electron irradiated silicon are presented. Two isolated TSC peaks are observed centerd around 150 and 250 °K. The peaks were studied by controlled variation of the sample heating rate. The results indicate the presence of hole trapping centers having energy levels of (Ev + 0.25) and (Ev + 0.42) eV. These levels are related to the defect centers observed in the same set of samples by study of the extrinsic photoconductivity. Nous donnons des resultats de conductivite stimule par des processus thermiques (TSC) obtenus sur du silicium qui est sans oxygen et qui est irradie avec des electrons. Deux maxima isoles du TSC sont visibles a environ 150 et 250 °K. Les maxima etaient etudies en faisant varies le tout de chauffage de l'enchantillon d'un facon controlle. Les resultats indiquent la presence de centres de pieges des trous avec niveaux d'energie de (Ev + 0,25) et (Ev + 0,42) eV. Ces niveaux sont lies aux centres des defaults observes dans la meme serie d'enchantillons en utilisant la method de la photoconductivite. Ces deux etudes ensemble tendent a confirme l'hypothese d'un distortion du reseau dependant de l'etat des charges au voisinage des defaults.

Defect centers in silicon produced by room temperature electron irradiation. I. Optical and photoconductivity studies

The results of photoconductivity measurements on high resistivity, oxygen free, electron irradiated silicon are presented. Narrow peaks, seen in photoconductivity, are shown to arise from local excitations of the defects produced. It is shown that the dominant defects produced are the divacancy and a second type of defect, possibly the K-center. The results support the view of a charge state dependent lattice distortion near the defects. The defect lattice interaction energy is estimated to be ≈60 meV. Nous donnons ici des resultats experimentaux de la photoconductivite et de l'absorption obtenus sur le silicium a haute resistivite, sans oxygen et irradie avec des electrons. Nous demonstrons que les maxima etroit dans le spectre de photoconductivite proviement des excitations locals des defaǔlts. Nous demontrons que les defaǔlts principaux produits sont le “divacancy” et un deuxieme type de defaǔlt peut etre le “K-centre”, deja observe dans EPR. Les resultats tendent a confirmes l'hypotheGse d'un distortion du reseau dependant de l'etat des charges au voisinage des defaǔlts. L'energie d'interaction du au defaǔlt du reseau est estime a environ 60 meV.

Properties of 1.0-MeV-Electron-Irradiated Defect Centers in Silicon

The presence of electrically active defects in 1.0-MeV-electron-irradiated silicon was observed using thermally stimulated capacitance measurements. Thermal-emission rates and activation energies of trapped majority carriers, impurity dependences, and annealing behavior of these defects were determined. The introduction of defects by annealing was observed. A total of 14 thermal-activation energies were measured. The oxygen-vacancy pair and the phosphorous-vacancy pair were correlated with thermal-activation energies of 174 and 471 meV through impurity dependences and annealing behavior. Comparison with other published data was made. The charge states were measured and it was found that the defects above midgap are acceptors; those below midgap are donors.