Features of the Carrier Concentration Determination during Irradiation of Wide-Gap Semiconductors: The Case Study of Silicon Carbide.

In this paper, the features of radiation compensation of wide-gap semiconductors are discussed, considering the case study of silicon carbide. Two classical methods of concentration determination are compared and analyzed: capacitance-voltage (-) and current-voltage () characteristics. The dependence of the base resistance in high-voltage 4H-SiC Schottky diodes on the dose of irradiation by electrons and protons is experimentally traced in the range of eight orders of magnitude.

Radiation Hardness of Silicon Carbide upon High-Temperature Electron and Proton Irradiation.

The radiation hardness of silicon carbide with respect to electron and proton irradiation and its dependence on the irradiation temperature are analyzed. It is shown that the main mechanism of SiC compensation is the formation of deep acceptor levels. With increasing the irradiation temperature, the probability of the formation of these centers decreases, and they are partly annealed out.

Microstructure of bismuth centers in silicon before and after irradiation with 15 MeV protons.

A decrease of two-gamma annihilation rate of a positron in a strong spin-orbit field of the annihilation site of bismuth impurity centerBi (= 9/2) in silicon with natural isotope composition was revealed (is the nuclear spin). This decrease was observed along with increasing occupancy of Bi donor states (binding energy{Bi} ≈ 69 meV). Atoms ofSi (= 1/2) isotope are involved in spin interactions of positron with Bi impurity centers.

Anti-thrombotic effects of nebivolol and carvedilol: Involvement of β2 receptors and COX-2/PGI2 pathways.

Background: Third generation β-adrenolytics, such as selective β1 adrenoceptor antagonist nebivolol and non-selective β1/β2 and α1 adrenoceptor antagonist carvedilol, display beneficial nitric oxide (NO)-dependent vasodilator activities that contribute to their therapeutic efficacy. In the present work, we analyzed whether nebivolol and carvedilol, as well as other β-adrenolytics with similar pharmacological profiles (selective β1 adrenoceptor antagonist - atenolol and non-selective α/β adrenoceptor antagonist - labetalol), possess the ability to induce PGI2-dependent anti-thrombotic activity in vivo in normotensive rats.

Methods: Anti-thrombotic effects of nebivolol and carvedilol were studied in vivo in anaesthetized rats with extracorporeal circulation superfusing collagen strips.

Positron annihilation on defects in silicon irradiated with 15 MeV protons.

Microstructure and thermal stability of the radiation defects in n-FZ-Si ([P] ≈ 7 × 10(15) cm(-3)) single crystals have been investigated. The radiation defects have been induced by irradiation with 15 MeV protons and studied by means of both the positron lifetime spectroscopy and low-temperature measurements of the Hall effect. At each step of the isochronal annealing over the temperature range ∼60-700 °C the positron lifetime has been measured for the temperature interval ∼30-300 K, and for samples-satellites the temperature dependences of the charge carriers and mobility have been determined over the range ∼4.