Resonant tunneling of holes in double-barrier structures in the presence of an in-plane magnetic field

Using the asymptotic transfer-matrix method, we investigate me resonant tunneling of holes in double-barrier semiconductor structures in the presence of an in-plane magnetic field. The transmission coefficients including ll (light to light hole), hl (light to heavy hole), hh (heavy to heavy hole), and lh (heavy to light hote) are calculated as a function of energy. As in the case of nonzero parallel wave vectors, the mixing of note tunneling can also occur due to the in-plane magnetic field. Moreover, as has been observed by resonant magnetotunneling spectroscopy, we also find that the different resonances have quite different magnetic-field dependences. © 1996 American Institute of Physics.published_or_final_versio

A deep level transient spectroscopy study of electron irradiation induced deep levels in p-type 6H–SiC

1.7 MeV electron irradiation-induced deep levels in p-type 6H–SiC have been studied using deep level transient spectroscopy. Two deep hole traps are observed, which are located at EV+0.55 eV and EV+0.78 eV. They have been identified as two different defects because they have different thermal behaviors. These defects at EV+0.55 eV and EV+0.78 eV are annealed out at 500–200 °C, respectively, and are different from the main defects E1/E2, Z1/Z2 observed in electron irradiated n-type 6H–SiC. This indicates that new defects have been formed in p-type 6H–SiC during electron irradiation. ©1999 American Institute of Physics.published_or_final_versio

Electron-irradiation-induced deep levels in n-type 6H–SiC

The fluence-dependent properties and the annealing behavior of electron-irradiation-induced deep levels in n-type 6H–SiC have been studied using deep-level transient spectroscopy (DLTS). Sample annealing reveals that the dominant DLTS signal at EC – 0.36 eV (labeled as E1 by others) consists of two overlapping deep levels (labeled as ED3L and ED3H). The breakup temperature of the defect ED3L is about 700 °C. The ED3H center together with another deep level located at EC – 0.44 eV (so-called E2) can withstand high-temperature annealing up to 1600 °C. It is argued that the involvement of the defect ED3L is the reason that various concentration ratios of E1/E2 were observed in the previous work. The revised value of the capture cross section of the deep-level ED3H has been measured after removing ED3L by annealing. A deep level found at EC – 0.50 eV is identified as a vacancy–impurity complex since it was found to have a lower saturated concentration and weak thermal stability. Two other deep levels, EC – 0.27 eV and EC – 0.32 eV, which were not observed by others because of the carrier freeze-out effect, are also reported. ©1999 American Institute of Physics.published_or_final_versio

Deep level transient spectroscopy study of particle irradiation induced defects in n-6H-SiC (Abstract)

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Deep level transient spectroscopic study of neutron-irradiated n-type 6H-SiC

A study of neutron-irradiated n-type 6H-SiC using deep level transient spectroscopy was presented. 100- 1600°C isochronal annealing was performed on the as-irradiated samples with each of the annealing steps to investigate the thermal annealing behavior. Thermal generation of deep levels NE1- NE4 at annealing temperatures above 1400°C was observed.published_or_final_versio

Gallium implantation induced deep levels in n-type 6H-SIC

Two Ga-acceptor levels, located at EV+0.31eV and EV+0.37eV, respectively, have been observed in the gallium implantation manufactured p+n diodes using deep level transient spectroscopy. The behavior of the implanted gallium is very similar to that of implanted aluminum, except that the positions of the introduced levels are different. This result strongly supports the recent model, which was used to explain the discrepant results between boron and aluminum implantation induced deep levels. Besides the two acceptor levels, a thermally stable electron trap is also observed and has been tentatively attributed to a Ga-related complex. © 1999 American Institute of Physics.published_or_final_versio

Aluminum-implantation-induced deep levels in n-type 6H–SiC

Deep-level defect centers on the n-side of p+n junction diodes formed by low and elevated temperature aluminum-ion implantation into n-type 6H–SiC have been studied using deep-level transient spectroscopy. Two shallow Al-acceptor levels have been observed in the n region just beyond the implantation depth through their minority-carrier emission signatures. The dominant level is situated at 0.26 eV above the valence band and is accompanied by a shallower level of small intensity. Comparison with photoluminescence results suggests the dominant level (labeled Ak) and the shallower level (labeled Ah), are associated with the cubic and hexagonal lattice sites, respectively. Unlike previously reported results, which show many different implantation-induced donors within the implantation region, only one deep donor level at EC – 0.44 eV is found to occur in the postimplantation region, indicating that the various crystal damage sites occur with different spatial distributions. ©1998 American Institute of Physics.published_or_final_versio

A deep level transient spectroscopy study of beryllium implanted n-type 6H-SiC

Beryllium implantation induced defects in 6H-SiC pn junctions have been investigated by deep level transient spectroscopy. Five defect centers labeled BE1, BE2, BE3, BE4, and BE5 have been detected in the temperature range 100-450 K. A comparative study has also been performed in low beryllium doped n-type 6H-SiC, which proved that the BE1, BE2, and BE3 centers are electron traps located at 0.34, 0.44, and 0.53 eV, respectively, below the conduction band edge. On the other hand, the BE4 and BE5 centers have been found to be hole traps which are situated at 0.64 and 0.73 eV, respectively, above the valence band edge. Possible defect configurations associated with these deep levels are discussed. © 2000 American Institute of Physics.published_or_final_versio

Deep level traps in the extended tail region of boron-implanted n-type 6H-SiC

Deep traps in the boron extended tail region of ion implanted 6H-SiC pn junctions formed during annealing have been studied using deep level transient spectroscopy. Dramatically high concentrations of ∼1016 cm-3 of the D center have been observed through the unusual appearance of minority peaks in the majority carrier spectra. No evidence is found for any shallow boron acceptor in this region, but an induced hole trap Ih at EV+0.46 eV is found under cold implantation conditions. These results support the picture of the extended tail, rich in boron-vacancy complexes such as the D center, which forms as a result of vacancy enhanced indiffusion. The dominance of the electrically active D center in the depletion layer of the technologically important SiC pn junction diode suggests the need for further research in this area. © 1998 American Institute of Physics.published_or_final_versio

Anomalous behaviors of E1 E2 deep level defects in 6H silicon carbide

Deep level defects E1 E2 were observed in He-implanted, 0.3 and 1.7 MeV electron-irradiated n -type 6H-SiC. Similar to others' results, the behaviors of E1 and E2 (like the peak intensity ratio, the annealing behaviors or the introduction rates) often varied from sample to sample. This anomalous result is not expected of E1 E2 being usually considered arising from the same defect located at the cubic and hexagonal sites respectively. The present study shows that this anomaly is due to another DLTS peak overlapping with the E1 E2. The activation energy and the capture cross section of this defect are EC -0.31 eV and σ∼8× 10-14 cm2, respectively. © 2005 American Institute of Physics.published_or_final_versio