Deep Levels in 4H Silicon Carbide Epilayers Induced by Neutron-Irradiation up to 10 16 n/cm 2
- PDF / 1,586,049 Bytes
- 10 Pages / 612 x 792 pts (letter) Page_size
- 17 Downloads / 184 Views
0911-B06-01
Deep Levels in 4H Silicon Carbide Epilayers Induced by Neutron-Irradiation up to 1016 n/cm2 Anna Cavallini1, Antonio Castaldini1, Filippo Nava2, Paolo Errani2, and Vladimir Cindro3 1 Physics, University of Bologna, Viale Berti Pichat 6/2, Bologna, 40127, Italy 2 Physics, University of Modena, Via Campi 183, Modena, 41100, Italy 3 Neutron Irradiation Facility, Josef Stefan Institute, Josef Stefan Institute Yadranska 39, Ljublljana, 1000, Slovenia
ABSTRACT We investigated the electronic levels of defects introduced in 4H-SiC α-particle detectors by irradiation with 1 MeV neutrons up to fluence equal to 8x1015 cm-2. As well, we investigated their effect on the detector radiation hardness. This study was carried out by deep level transient spectroscopy (DLTS) and photo-induced current transient spectroscopy (PICTS). As the irradiation level approaches fluences in the order of 1015 cm-2, the material behaves as highly resistive due to a very great compensation effect but the diodes are still able to detect with a acceptably good charge collection efficiency (CCE) equal to 80%. By further increasing fluence, CCE decreases reaching the value of ≈ 20% at fluence of 8x1015 cm-2. The dominant peaks in the PICTS spectra occur in the temperature range from 400 to 700 K. Enthalpy, capture cross-section and order of magnitude of the density of such deep levels were calculated. In the above said temperature range the deep levels associated to the radiation induced defects play the key role in the degradation of the CCE. Two deep levels at Et = 1.18 eV and Et = 1.50 eV are likely to be responsible of such dramatic decrease of the charge collection efficiency. These levels were reasonably associated to an elementary defect involving a carbon vacancy and to a defect complex involving a carbon and a silicon vacancy, respectively.
INTRODUCTION Silicon carbide (SiC), namely its polytype 4H, is being proposed for high energy particle experiments. Due to the expected total fluence of fast hadrons above 1016 cm-2 in a possible upgrade of the Large Hadron Collider (LHC) at CERN to a ten time increased luminosity of 1035 cm-2s-1, the detectors that are planned in view of this upgrade must be ultra radiation hard providing a fast and efficient charge collection [1]. Silicon carbide is one of the most promising wide band gap materials due to its high breakdown electric field, high electron saturation velocity, high operating temperature and high radiation hardness properties [2, 3]. For these reasons over the last few years considerable effort has been concentrated on better understanding the detection performance of silicon carbide detectors after heavy irradiation. The most recent results concern the use of semiconductors epitaxial 4H-SiC [4- 10] as well as semi-insulating 4H-SiC materials [11- 13]. It is well known that the degradation of the detectors with irradiation is caused by lattice defects like creation of vacancies (point-like defects) or of damaged regions (clusters). Thus, the
understanding of the irradiated dete
Data Loading...
