Optical cross sections of deep levels in 4H-SiC

Abstract

Deep levels by proton and electron irradiation in 4H-SiC J. Appl. Phys. 98, 053706 (2005);We have characterized deep levels in 4H-SiC epilayers grown by cold wall chemical vapor deposition by the deep level transient spectroscopy ͑DLTS͒ and the optical-capacitance-transient spectroscopy ͑O-CTS͒. Four kinds of DLTS peaks were detected in the epilayers. Three of them are identified as the Z 1/2 , EH 6/7 , and RD 1/2 centers, while the other one has never been reported previously, and was named the NB center. On the basis of these DLTS data we have estimated the thermal ionization energies. The classical optical ionization energies of these centers, which are given by the sums of thermal ionization energies and Franck-Condon shifts, were estimated via fittings of the measured optical cross sections from O-CTS data by means of a sufficiently general theoretical model. Temperature dependences of nonradiative multiphonon carrier capture cross sections for the Z 1/2 and NB centers were roughly estimated in terms of parametrical dependences on thermal ionization energies and Franck-Condon shifts.

Observation of deep levels and their hole capture behavior in p-type 4H-SiC epilayers with and without electron irradiation

“…Such a dependence on injection pulse width is typically observed at injection pulse widths of less than 1 µs. 30) However, our samples have low hole concentrations and thus the capture processes slowly proceeded, resulting in the pulse-width dependences for widths on the order of ms. Figure 7 shows the relation between the injection pulse width and 1 À n t =N T , where n t is the concentration of the traps occupied by a carrier during the injection pulse, for the deep levels in the samples without annealing.…”

Carrier Lifetime Controlling Defects Z1/2 and RB1 in Standard and Chlorinated Chemistry Grown 4H-SiC

“…Kotamraju et al detected a deep level at a similar position to RB1 using chlorinated carbon precursors in a cell contaminated with Fe and V at a low growth temperature of 1300 °C. A level identified as RD1/2 was found in another study in 4H-SiC samples grown at 1500 °C in a cold-wall MOCVD reactor …”

“…A level identified as RD1/2 was found in another study in 4H-SiC samples grown at 1500 °C in a cold-wall MOCVD reactor. 25 Several more levels were detected after implantation or irradiation with different species and have parameters very close to RB1 but were found to anneal out at temperatures below 1500 °C, 26,27,28 except in the study by Reshanov, et al 29 . Table 5 lists the DLTS deep level parameters and annealing or growth temperatures for all of these levels.…”

Patterned tungsten disulfide/graphene heterostructures for efficient multifunctional optoelectronic devices

“…Nevertheless, their optical activation occurs on the time scale of tens of seconds and their carrier trap cross section is quite low compared with other SiC trap states. 30 This prevents EH 6/7 states from affecting AC measurements. For the detectivity, calculated…”