Оцінка атомного заряду в нітридах бору

Boron nitrides (BN) are compounds with bonds of covalent–ionic type. Therefore, binding polarity is an important characteristic affecting their physical properties. Dependencies of measurable parameters on static effective charges of constituent atoms are so complex that, these are virtually undetectable experimentally. As for the theoretically obtained atomic charges in boron nitrides, they are characterized by a significant scatter making them almost unreliable. The general reason for this lies in the impossibility of unambiguous division of the electron density between atoms of elements. It pushes the search for a semiempirical solution of the problem.We have derived the expression for the effective charge number  in a binary compound (effective charges of B and N atoms should be  and , respectively) depending on number of molecules  in primitive parallelogram, its sectional area  transverse to the external electric field direction, Young’s modulus  and permittivity  in same direction. Semiempirically estimated values of  (in - and -directions) are physically reasonable: hexagonal h-BN – 0.35 and 0.09, cubic c-BN – 0.49, and wurtzite-like w-BN boron nitrides – 0.76 and 0.50.Also quite natural are qualitative conclusions: in h-BN intra-layer bonds polarity is much stronger than that between hexagonal layers; bonds are stronger polarized in denser modifications c-BN and w-BN, which are characterized by higher coordination numbers as well; bonds polarities in c-BN and along -axis in w-BN are almost indistinguishable; and bonds polarities in - and -directions in w-BN are different.Obtained static charges can be used in the refinement of the BN electron structure calculations.Для бинарных соединений выведено выражение эффективных зарядов, зависящее от числа молекул в элементарном параллелограме, площади его сечения поперек внешнему полю, модули Юнга и диэлектрической проницаемости. Для нитридов бора были получены следующие полуэмпирические оценки: h-BN – 0.35 и 0.09, c-BN – 0.49, и w-BN – 0.76 и 0.50.Для бінарних сполук виведено вираз ефективних зарядів, залежних від числа молекул в елементарній паралелограмі, площі його перетину поперек зовнішньому полю, модулі Юнга і діелектричній проникності. Для нітридів бору були отримані наступні напівемпіричні оцінки: h-BN – 0.35 і 0.09, c-BN – 0.49, і w-BN – 0.76 і 0.50

Роль бора у формуванні вторинних радіаційних дефектів в кремнії

Influence of boron impurities on electron-transport in crystalline silicon is well known because p-Si – basic semiconducting material of the modern microelectronics – usually is obtained by doping with B. It is too important to understand the mechanism interaction of B dopants with radiation defects in silicon to (i) develop effective radiation treatment technologies for electronic devices and integrated circuits, (ii) improve their radiation resistance, and (iii) design effective solid-state radiation sensors and detectors.Based on authors’ previous works the role of B-impurities in formation of secondary radiation defects in Si crystals is investigated. Dependences of these processes on isochronous annealing temperature (80–600 °C) are studied by using the Hall measurements of temperature-dependencies (100–300 K) of holes’ concentration and mobility in silicon before and after irradiation with 8 MeV electrons at the dose of 5∙1015 cm–2. Two main conclusions are made: boron atoms in silicon crystals (i) serve as extremely active sinks of radiation defects, and (ii) participate in space-charge-screening of the relatively high-conductive inclusions in form of clusters of radiation defects.Основываясь на прежние работы авторов исследована роль примесей бора (B) в формировании вторичных радиационных дефектов в кристаллах кремния (Si). Зависимости этих процессов от температуры изохронного отжига (в интервале 80–600 °C) изучены с использованием холловских измерений температурных зависимостей (в интервале 100–300 К) концентрации и подвижности дырок в кремний до и после облучения электронами с энергией около 8 МэВ при дозе 5∙1015 см–2.Ґрунтуючись на колишні роботи авторів, досліджено роль домішок бору (B) у формуванні вторинних радіаційних дефектів в кристалах кремнію (Si). Залежності цих процесів від температури ізохронного відпалу (в інтервалі 80-600 °C) вивчені з використанням холлівських вимірювань температурних залежностей (в інтервалі 100-300 К) концентрації і рухливості дірок в кремній до і після опромінення електронами з енергією близько 8 МэВ при дозі 5∙1015 см–2

Оцінка атомного заряду в нітридах бору

Boron nitrides (BN) are compounds with bonds of covalent–ionic type. Therefore, binding polarity is an important characteristic affecting their physical properties. Dependencies of measurable parameters on static effective charges of constituent atoms are so complex that, these are virtually undetectable experimentally. As for the theoretically obtained atomic charges in boron nitrides, they are characterized by a significant scatter making them almost unreliable. The general reason for this lies in the impossibility of unambiguous division of the electron density between atoms of elements. It pushes the search for a semiempirical solution of the problem.We have derived the expression for the effective charge number  in a binary compound (effective charges of B and N atoms should be  and , respectively) depending on number of molecules  in primitive parallelogram, its sectional area  transverse to the external electric field direction, Young’s modulus  and permittivity  in same direction. Semiempirically estimated values of  (in - and -directions) are physically reasonable: hexagonal h-BN – 0.35 and 0.09, cubic c-BN – 0.49, and wurtzite-like w-BN boron nitrides – 0.76 and 0.50.Also quite natural are qualitative conclusions: in h-BN intra-layer bonds polarity is much stronger than that between hexagonal layers; bonds are stronger polarized in denser modifications c-BN and w-BN, which are characterized by higher coordination numbers as well; bonds polarities in c-BN and along -axis in w-BN are almost indistinguishable; and bonds polarities in - and -directions in w-BN are different.Obtained static charges can be used in the refinement of the BN electron structure calculations.Для бинарных соединений выведено выражение эффективных зарядов, зависящее от числа молекул в элементарном параллелограме, площади его сечения поперек внешнему полю, модули Юнга и диэлектрической проницаемости. Для нитридов бора были получены следующие полуэмпирические оценки: h-BN – 0.35 и 0.09, c-BN – 0.49, и w-BN – 0.76 и 0.50.Для бінарних сполук виведено вираз ефективних зарядів, залежних від числа молекул в елементарній паралелограмі, площі його перетину поперек зовнішньому полю, модулі Юнга і діелектричній проникності. Для нітридів бору були отримані наступні напівемпіричні оцінки: h-BN – 0.35 і 0.09, c-BN – 0.49, і w-BN – 0.76 і 0.50

Роль бора у формуванні вторинних радіаційних дефектів в кремнії

Influence of boron impurities on electron-transport in crystalline silicon is well known because p-Si – basic semiconducting material of the modern microelectronics – usually is obtained by doping with B. It is too important to understand the mechanism interaction of B dopants with radiation defects in silicon to (i) develop effective radiation treatment technologies for electronic devices and integrated circuits, (ii) improve their radiation resistance, and (iii) design effective solid-state radiation sensors and detectors.Based on authors’ previous works the role of B-impurities in formation of secondary radiation defects in Si crystals is investigated. Dependences of these processes on isochronous annealing temperature (80–600 °C) are studied by using the Hall measurements of temperature-dependencies (100–300 K) of holes’ concentration and mobility in silicon before and after irradiation with 8 MeV electrons at the dose of 5∙1015 cm–2. Two main conclusions are made: boron atoms in silicon crystals (i) serve as extremely active sinks of radiation defects, and (ii) participate in space-charge-screening of the relatively high-conductive inclusions in form of clusters of radiation defects.Основываясь на прежние работы авторов исследована роль примесей бора (B) в формировании вторичных радиационных дефектов в кристаллах кремния (Si). Зависимости этих процессов от температуры изохронного отжига (в интервале 80–600 °C) изучены с использованием холловских измерений температурных зависимостей (в интервале 100–300 К) концентрации и подвижности дырок в кремний до и после облучения электронами с энергией около 8 МэВ при дозе 5∙1015 см–2.Ґрунтуючись на колишні роботи авторів, досліджено роль домішок бору (B) у формуванні вторинних радіаційних дефектів в кристалах кремнію (Si). Залежності цих процесів від температури ізохронного відпалу (в інтервалі 80-600 °C) вивчені з використанням холлівських вимірювань температурних залежностей (в інтервалі 100-300 К) концентрації і рухливості дірок в кремній до і після опромінення електронами з енергією близько 8 МэВ при дозі 5∙1015 см–2

Effect of concentrated light on morphology and vibrational properties of boron and tantalum mixtures

Heating a mixture of boron (impurities: carbon ∼ B50C2, boric acid – H3BO3) and tantalum (Ta) powders in nitrogen flow in a xenon high-flux optical furnace was performed. As-received powder composed of h-BN, H3BO3, TaB2, B9H11 and a number of other phases including β-rhombohedral boron, apparently, heavily doped with Ta. FT–IR examination of any sample of the material reveals the complicated vibration spectrum containing, in particular, an absorption band near 2260 cm−1. The shapes of these bands are different for samples because powders were synthesized at different temperatures. Known, that in β-rhombohedral boron lattice, there are nano-sized voids of different types, which allow an accommodation of single atoms or small groups of atoms. Theoretical calculations performed by the method of quasi-classical type yields the same value, 2260 cm−1, for the vibrations frequency of Ta atoms in D-type crystallographic voids in β-rhombohedral boron lattice. Since, Ta atoms are known to prefer accommodation just in D-voids the experimentally detected bands can be identified with localized vibrations of Ta atoms