Carbon-Related Defects in Si:C/Silicon Heterostructures Assessed by Deep-Level Transient Spectroscopy (original) (raw)
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Nanoscience and …, 2010
p-type 4H-SiC epitaxial layers grown by chemical vapor deposition have been implanted with 200 and 100 keV protons at five different implantation temperatures. An isochronal annealing series was performed from 100 to 1800°C, and Al-doped epitaxial layers have been characterized by means of deep level transient spectroscopy ͑DLTS͒ after each annealing step. DLTS measurements were carried out in the 150-670 K temperature range and revealed the presence of eight hole traps located in the 0.18-1.8 eV range above the valence band ͑E V ͒. Heat treatments for temperatures above 700°C showed the progressive reactivation of the Al doping in the implanted region, which is completed after a 1500°C annealing treatment. Two traps located at E V + 0.44 eV and E V + 1.8 eV are persistent even after annealing at 1800°C, while the other traps anneal out after heat treatments at ഛ1700°C. An activation energy for dissociation of 6.2 eV is estimated for the hole trap at E V + 0.79 eV, and the nature of this defect is discussed on the basis of previous experimental results and theoretical calculations. Furthermore, the study of the annealing behavior as a function of the implantation temperature shows that the detected traps display an increase of concentration for increasing implantation temperatures.
Study of electrically active defects in epitaxial layers on silicon
2016 China Semiconductor Technology International Conference (CSTIC), 2016
Electrically active defects in silicon-based epitaxial layers on silicon substrates have been studied by Deep-Level Transient Spectroscopy (DLTS). Several aspects have been investigated, like, the impact of the pre-epi cleaning conditions and the effect of a post-deposition anneal on the deep-level properties. It is shown that the pre-cleaning thermal budget has a strong influence on the defects at the substrate/epi layer interface. At the same time, a post-deposition Forming Gas Anneal can passivate to a large extent the active defect states. Finally, it is shown that application of a post-deposition anneal increases the out-diffusion of carbon from a Si:C stressor layer into the p-type CZ substrate.
Physical Review B, 2000
We have considered five different models of charge transfer among coupled defect states in semiconductors where the free-carrier density is limited by the density of unoccupied trap levels, as in the case of defectdominated materials. To determine the time dependence of the trap occupancy features, we formulate a set of coupled differential equations that govern charge capture and emission processes for two defect states. A numerical solution assuming model parameters for traps provides features of the trap occupancy as a function of time. A critical comparison is made in occupancy features for different models, primarily categorized as serial ͑hierarchical͒ and parallel mechanisms of charge transfer. The model predictions are successfully applied to a study of trapping kinetics of defects observed in heavily damaged n-type silicon. We show that, in addition to the occurrence of charge redistribution among multiple traps, the major trap in the damaged silicon exists in two metastable configurations, perhaps with negative U ͑Hubbard correlation energy͒, and the stable configuration refers to a midgap compensating center related to a small cluster of self-interstitials. The applicability of our model simulations can be extended to more complex defect systems using a combination of these simple models.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2002
The annealing of interstitial carbon C i after 7-10 MeV and 23 GeV proton irradiations at room temperature in high resistivity n-type silicon is investigated. Deep level transient spectroscopy is used to determine the defect parameters. The annealing characteristics of the impurity defects C i , C i C s , C i O i and V O i suggest that the mobile C i atoms are also captured at divacancy V V sites at the cluster peripheries and not only at C s and O i sites in the silicon bulk. The deviation of the electrical filling characteristic of C i from the characteristic of a homogeneously distributed defect can be explained by an aggregation of C i atoms in the environment of the clusters. The capture rate of electrons into defects located in the cluster environment is reduced due to a positive space charge region surrounding the negatively charged cluster core. The optical filling characteristic of C i suggests that the change of the triangle shaped electric field distribution in a reverse biased p + n junction due to charged clusters is negligible.
Electrically active defects in as-implanted, deep buried layers in p-type silicon
Journal of Applied Physics, 1997
We have studied electrically active defects in buried layers, produced by heavy ion implantation in silicon, using both conventional deep level transient spectroscopy ͑DLTS͒ and an isothermal spectroscopic technique called time analyzed transient spectroscopy operated in constant capacitance mode ͑CC-TATS͒. We show that CC-TATS is a more reliable method than DLTS for characterization of the heavily damaged buried layers. The major trap produced in the buried layers in p-type Si by MeV Ar ϩ implantation is found to have an energy level at E v ϩ0.52 eV. This trap, believed to be responsible for compensation in the damaged layer, shows exponential capture dynamics. We observed an unusually high thermal activation energy for capture, which is attributed to a macroscopic energy barrier for carriers to reach the buried layer. We observe two other majority carrier traps, and also a minority carrier trap possibly due to inversion within the depletion layer.
Investigation of C[sub x]Si defects in C implanted silicon by transmission electron microscopy
Applied Physics Letters, 1997
Buried C x Si layers were produced by high-energy implantation of carbon into CZ silicon. The depth distribution of carbon, the morphology of the buried layers, as well as the precipitation of C were investigated as functions of rapid thermal annealing between 700 and 1300°C, using transmission electron microscopy, secondary ion mass spectroscopy, and positron annihilation measurements. Different kinds of microdefects occur: below Ϸ800°C there are vacancy agglomerates as well as metastable C-Si agglomerates ͑⌽Ϸ2 nm͒, whereas at higher temperatures -SiC precipitates are observed. Results are discussed in terms of the interaction between C atoms and radiation-induced defects.
Effect of temperature on thermally induced defects in silicon
Journal of Materials Science: Materials in Electronics, 2008
Deep level transient spectroscopy has been used to study thermally activated defects in silicon. It has been observed that different annealing temperatures activate different defects in silicon, which were lying on inactive sites before annealing. Two deep mid-gap levels at energy positions E c -0.48 eV and E c -0.55 eV were found to be introduced by different heat treatments. It is also noted that heat treatment at 1,250°C suppresses the concentration of deep level at E c -0.23 eV and enhances the concentration of deep level at E c -0.25 eV, while heat treatment at 950°C has an opposite effect. Annealing response of the level at E c -0.48 eV is found different to the annealing response of the level at E c -0.55 eV which suggests them two different levels.
MRS Proceedings, 1998
We have carried out electrical characterization of defects in heavily damaged silicon, where damage is created by MeV heavy ions at doses near but below amorphization threshold. Trapping kinetics over several orders of magnitude in time have been monitored using isothermal spectroscopy called Time Analyzed Transient Spectroscopy (TATS). Two distinct effects regarding the nature of changes in density of states in the gap have been demonstrated. Firstly, we show that charge redistribution among multiple traps occur such that only the occupancy of the deeper states increase at the cost of shallower ones for long time filling. Secondly, a novel defect relaxation mechanism is observed for samples with relatively lower damage. A trap is seen to exhibit progressive deepening in energy with increase in filling time, finally stabilizing for large filling times. From the athermal nature of associated TATS peaks, it is argued that the relaxation involves large entropic contribution to free ene...