Rare earth interstitial-complexes in Ge : hybrid density functional studies

Please read abstract in the article.The National Research Foundation (NRF) of South Africa [98961]http://www.elsevier.com/locate/nimb2018-10-15hj2017Physic

Rare earth substitutional impurities in germanium : a hybrid density functional theory study

Please read abstract in the article.The National Research Foundation (NRF) of South Africa [(UID) 98961]http://www.elsevier.com/locate/nimb2018-10-15hj2017Physic

Induced defect levels of P and Al vacancy-complexes in 4H-SiC : a hybrid functional study

Please read abstract in the article.The National Research foundation (NRF) of South Africa (Grant specific unique reference number (UID) 98961).http://www.elsevier.com/locate/mssp2020-01-01hj2018Physic

Determination of capture barrier energy of the e-center in palladium Schottky barrier diodes of antimony-doped germanium by varying the pulse width

Please read abstract in the article.The National Research Foundation (NRF) of South Africahttp://iopscience.iop.org/journal/2053-1591am2020Physic

Electrical characterization of 5.4 MeV alpha-particle irradiated 4H-SiC with low doping density

Nickel Schottky diodes were fabricated on 4H-SiC. The diodes had excellent current rectification with about ten orders of magnitude between 50 V and +2 V. The ideality factor was obtained as 1.05 which signifies the dominance of the thermionic emission process in charge transport across the barrier. Deep level transient spectroscopy revealed the presence of four deep level defects in the 30–350 K temperature range. The diodes were then irradiated with 5.4 MeV alpha particles up to fluence of 2.6 1010 cm 2. Current–voltage and capacitance–voltage measurements revealed degraded diode characteristics after irradiation. DLTS revealed the presence of three more energy levels with activation enthalpies of 0.42 eV, 0.62 eV and 0.76 eV below the conduction band. These levels were however only realized after annealing the irradiated sample at 200 C and they annealed out at 400 C. The defect depth concentration was determined for some of the observed defects.National Research Foundation (NRF) of South Africa.http://www.elsevier.com/locate/nimb2016-09-30hb201

Electrical characterization of deep levels created by bombarding nitrogen-doped 4HSiC with alpha-particle irradiation

Deep-level transient spectroscopy (DLTS) and Laplace-DLTS were used to investigate the effect of alpha-particle irradiation on the electrical properties of nitrogen-doped 4H-SiC. The samples were bombarded with alpha-particles at room temperature (300 K) using an americium-241 (241Am) radionuclide source. DLTS revealed the presence of four deep levels in the as-grown samples, E0.09, E0.11, E0.16 and E0.65. After irradiation with a fluence of 4.1 × 1010 alpha-particles-cm–2, DLTS measurements indicated the presence of two new deep levels, E0.39 and E0.62 with energy level, EC – 0.39 eV and EC –0.62 eV, with an apparent capture cross sections of 2×10–16 and 2×10–14 cm2, respectively. Furthermore, irradiation with fluence of 8.9×1010 alpha-particles-cm–2 resulted in disappearance of shallow defects due to a lowering of the Fermi level. These defects - minutes. Defects, E0.39 and E0.42 with close emission rates were attributed to silicon or carbon vacancy and could only be separated by using high resolution Laplace-DLTS. The DLTS peaks at EC – (0.55-0.70) eV (known as Z1/Z2) were attributed to an isolated carbon vacancy (VC).This work is based on the research supported in part by the National Research Foundation (NRF) of South African (Grant specific unique reference number (UID) 78838).http://www.elsevier.com/locate/nimb2017-03-31hb2016Physic

Electrical characterization of defects introduced in n-type N-doped 4H-SiC during electron beam exposure

Deep level transient spectroscopy (DLTS) was used to characterize the defects introduced in n-type, N-doped, 4H-SiC while being exposed to electron beam evaporation conditions. This was done by heating a tungsten source using an electron beam current of 100 mA, which was not sufficient to evaporate tungsten. Two new defects were introduced during the exposure of 4H-SiC samples to electron beam deposition conditions (without metal deposition) after resistively evaporated nickel Schottky contacts. We established the identity of these defects by comparing their signatures to those of high energy particle irradiation induced defects of the same materials. The defect E0.42 had acceptor-like behaviour and could be attributed to be a silicon or carbon vacancy. The E0.71 had intrinsic nature and was linked to a carbon vacancy and/or carbon interstials.The National Research Foundation (NRF) of South African (Grant specific unique reference number (UID) 78838).https://www.scientific.net/SSPhb2017Physic

DLTS characterization of defects in GaN induced by electron beam exposure

The deep level transient spectroscopy (DLTS) technique was used to investigate the effects of electron beam exposure (EBE) on n-GaN. A defect with activation energy of 0.12 eV and capture cross section of 8.0 × 10-16 cm2 was induced by the exposure. The defect was similar to defects induced by other irradiation techniques such as proton, electron, and gamma irradiation. In comparison to GaN, the EBE induced defects in other materials such as Si and SiC are similar to those induced by other irradiation methods.The South African National Research Foundation (NRF)http://www.elsevier.com/locate/mssp2018-06-30hb2017Physic

Response of Ni/4H-SiC Schottky barrier diodes to alpha-particle irradiation at different fluences

Irradiation experiments have been carried out on 1.9 × 1016 cm–3 nitrogen-doped 4H-SiC at room temperature using 5.4 MeV alpha-particle irradiation over a fluence ranges from 2.6 × 1010 to 9.2 × 1011 cm–2. Current-voltage (I-V), capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) measurements have been carried out to study the change in characteristics of the devices and free carrier removal rate due to alpha-particle irradiation, respectively. As radiation fluence increases, the ideality factors increased from 1.20 to 1.85 but the Schottky barrier height (SBHI-V) decreased from 1.47 to 1.34 eV. Free carrier concentration, Nd decreased with increasing fluence from 1.7 × 1016 to 1.1 × 1016 cm–2 at approximately 0.70 μm depth. The reduction in Nd shows that defects were induced during the irradiation and have effect on compensating the free carrier. The free carrier removal rate was estimated to be 6480±70 cm–1. Alpha-particle irradiation introduced two electron traps (E0.39 and E0.62), with activation energies of 0.39±0.03 eV and 0.62±0.08 eV, respectively. The E0.39 as attribute related to silicon or carbon vacancy, while the E0.62 has the attribute of Z1/Z2.National Research Foundation (NRF) of South African (Grant specific unique reference number (UID) 78838).http://www.elsevier.com/locate/physb2017-01-31hb201

Electrical characterization of electron irradiated and annealed lowly-doped 4H-SiC

Please read abstract in the article.The University of Pretoria; Postdoctoral Fellowship Program of the University of Pretoria and the National Research Foundation (NRF) of South Africa.http://www.elsevier.com/locate/nimb2018-10-15hj2017Physic