Deep level transient spectroscopy study of defects at Si/SiO< inf> 2 and Si/Si< inf> 3 N< inf> 4 interfaces (original) (raw)
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Deep level transient spectroscopy study of defects in hydrogen implanted p-type 4H-SiC
Journal of Applied Physics, 2007
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.
Japanese Journal of Applied Physics, 2015
The effects of the oxidation atmosphere and crystal faces on the interface-trap density was examined by using constant-capacitance deep-level transient spectroscopy to clarify the origin of them. By comparing the DLTS spectra of the low-mobility interfaces oxidized in a N 2 O atmosphere with those of the high-mobility interfaces on C-face oxidized in a wet atmosphere, it was found that a high density of traps are commonly observed around the energy of 0.16 eV from the edge of the conduction band (C1 traps) in low-mobility interfaces irrespective of crystal faces. It was also found that the generation and elimination of traps specific to crystal faces: (1) the C1 traps can be eliminated by wet oxidation only on the C-face, and (2) the O2 traps (0.37 eV) can be observed in the SiC/SiO 2 interface only on the Si-face. The generation of O2 traps on the Si-face and the elimination of C1 traps on the C-face by wet oxidation may be caused by the oxidation reaction specific to the crystal faces.
High-Temperature Deep Level Transient Spectroscopy on As-Grown P-Type 4H-SiC Epilayers
Japanese Journal of Applied Physics, 2006
Deep levels in as-grown p-type 4H-SiC have been investigated. Three hole traps, namely HK2, HK3, and HK4, were detected by deep level transient spectroscopy (DLTS) in the temperature range from 350 to 700 K. The concentration of each trap is approximately 1{ 3 Â 10 12 cm À3. Activation energy is estimated to be E V þ 0:84 eV for HK2, E V þ 1:27 eV for HK3, and E V þ 1:44 eV for HK4. These hole traps may be donor-like (þ=0) traps according to the double-correlated DLTS measurements. The concentrations of HK3 and HK4 decrease below the detection limit (1 Â 10 11 cm À3) by annealing at 1350 C. On the other hand, the HK2 center is thermally more stable, the annealing temperature being approximately 1550 C.
Physica B: Condensed Matter, 2012
In this study deep level transient spectroscopy has been performed on boron-nitrogen co-doped 6H-SiC epilayers exhibiting p-type conductivity with free carrier concentration (N A -N D )$ 3 Â 10 17 cm À 3 . We observed a hole H 1 majority carrier and an electron E 1 minority carrier traps in the device having activation energies E v þ0.24 eV, E c À 0.41 eV, respectively. The capture cross-section and trap concentration of H 1 and E 1 levels were found to be (5 Â 10 À 19 cm 2 , 2Â 10 15 cm À 3 ) and (1.6Â 10 À 16 cm 2 , 3Â 10 15 cm À 3 ), respectively. Owing to the background involvement of aluminum in growth reactor and comparison of the obtained data with the literature, the H 1 defect was identified as aluminum acceptor. A reasonable justification has been given to correlate the E 1 defect to a nitrogen donor.
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.
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.
Journal of Applied Physics, 2007
The effect of the Schottky barrier height on the detection of the concentration of midgap defects using deep level transient spectroscopy ͑DLTS͒ is experimentally and theoretically studied for EH 6 and EH 7 defects in 4H-SiC. In this special case, the DLTS signal height for EH 6 and EH 7 increases with increasing barrier height and saturates at values above 1.5 and 1.7 eV, respectively. Below 1.1 eV, the DLTS peak completely disappears for both defects. The experimental data are explained by a theoretical model. The course of the quasi-Fermi level in the space charge region is calculated as a function of the reverse current through it, which is determined by the barrier height, and the reverse bias applied.
MRS Proceedings, 1998
We report on the electrical properties of defects introduced in epitaxially grown n-Si by 1 keV He-, Ne-, and Ar-ion bombardment. Epitaxial layers with different 0 contents were used in this study. We demonstrate using deep level transient spectroscopy that the low energy ions introduced a family of similarly structured defects (DI) with electronic levels at-0.20 eV below the conduction band. The introduction of this set of identical defects was not influenced by the presence of 0. Ion bombardment of O-rich Si introduced another family of prominent traps (D2) with levels close to the middle of the band gap. Both sets of defects were thermally stable up to-400 "C, and their annealing was accompanied by the introduction of a family of secondary defects (D3). The "D3" defects had levels at-0.21 eV below the conduction band and were thermally stable at 650 'C. We have proposed that the "DI", "D2", and "D3" defects are higherorder vacancy clusters (larger than the divacancy) or complexes thereof.
Defect energy levels in hydrogen-implanted and electron-irradiated n-type 4H silicon carbide
Journal of Applied Physics, 2005
Using deep level transient spectroscopy ͑DLTS͒, we have studied the energy position and thermal stability of deep levels in nitrogen doped 4H-SiC epitaxial layers after 1.2 MeV proton implantation and 15 MeV electron irradiation. Isochronal annealing was performed at temperatures from 100 to 1200°C in steps of 50°C. The DLTS measurements, which were carried out in the temperature range from 120 to 630 K after each annealing step, reveal the presence of ten electron traps located in the energy range of 0.45-1.6 eV below the conduction band edge ͑E c ͒. Of these ten levels, three traps at 0.69, 0.73, and 1.03 eV below E c , respectively, are observed only after proton implantation. Dose dependence and depth profiling studies of these levels have been performed. Comparing the experimental data with computer simulations of the implantation and defects profiles, it is suggested that these three new levels, not previously reported in the literature, are hydrogen related. In particular, the E c − 0.73 eV level displays a very narrow depth distribution, confined within the implantation profile, and it originates most likely from a defect involving only one H atom.