Effect of oxygen on some reactions of ZnSe crystal surface interaction with H₂O vapors, CO₂, and CO

Effect of oxygen on some interaction reactions of ZnSe crystal surface with water vapors, CO₂, and CO which result in release of hydrogen, and also carbon from a surface of crystals is discussed. Temperature dependences of equilibrium constants are calculated. It is found that participation of oxygen into the viewed processes of interacting results in sharp increase of probability and intensity of their actual behavior. It was shown that the essential contribution to these processes can be made by presence of antropogenic admixtures in air (water, hydrocarbons, CO₂, CO, engine exhaust fumes, etc.) which plays a critical part in pollution of ZnSe crystals surface by carbon

Microhardness and brittle strength of ZnSe₍₁₋ₓ₎Teₓ crystals grown from melt

Mechanical properties of ZnSe₍₁₋ₓ₎Teₓ solid solutions (0 < CTe < 1.3 mass % ) have been studied using indentation method in two modes (indenting and scratching). The breaking limits for doped and undoped crystals have been measured by uniaxial compression. For the crystals where the dopant concentration CTe≈0.3 %, the microhardness anisotropy coefficient is equal to unity. This can be explained by disappearance of stacking defects in the crystals at the mentioned tellurium concentration due to favorable conditions for the sphalerite structure in the solid solution. As the Te concentration in the solid solution varies within the 0.2 to 1.3 % range, the crystal microhardness has been shown to increase linearly by 23 %. The fact has been confirmed by measuring the brittle fracture limit for Te doped and undoped ZnSe crystals. The fact can be explained by local distortions of ZnSe lattice due to Te atoms present and by the dislocation mobility decrease associated thereto, the combination of both factors results in the material strengthening. Effect of heat treatment and the block boundaries on the strength limit and cracking resistance of ZnSe₍₁₋ₓ₎Teₓ crystals has been established that is of importance when the material is subjected to machining

Preparation of high-purity charge for growth of Cd₁₋ₓ ZnₓTe crystals

Possibilities have been studied to prepare high-purity charge for growth of Cd₁₋ₓ ZnₓTe crystals of high perfection and spectrometric quality. Studies have been carried out of deep purification of Cd, Zn and Te using the installation developed by us, which comprised a rotating container of optical quartz, by distillation and recrystallization. This installation is polyfunctional, allowing distillation, zone purification, recrystallization in horizontal (at a small angle) or vertical direction. It has been shown that horizontal zone purification is efficient for most admixtures, with exception of carbon. For carbon removal from Cd, Zn and Te, a vertical variant of zone purification was additionally used, which allowed reduction in carbon content from 10⁻³ to -10⁻⁶ %.Работа посвящена исследованию возможности получения высокочистой шихты для выращивания кристаллов Cd₁₋ₓ ZnₓTe высокого структурного совершенства и спектрометрического качества. Приведены результаты изучения процессов глубокой очистки Cd, Zn и Te при использовании разработанной нами установки с вращающимся контейнером из оптического кварца путем их дистилляции и перекристаллизации. Эта установка является многофункциональной и позволяет проводить дистилляцию, зонную очистку, перекристаллизацию как в горизонтальном (под небольшим углом), так и в вертикальном направлениях. Показано, что горизонтальная зонная очистка является эффективной для большинства примесей, за исключением углерода. Для очистки Cd, Zn и Te от примеси углерода дополнительно использован вертикальный вариант зонной очистки, который позволил снизить содержание углерода с с 10⁻³ до -10⁻⁶ %Робота присвячена досліджєнню можливості одержання шихти високої чистоти для вирощування структурно досконалих кристалів Cd₁₋ₓ ZnₓTe спектрометричної якості. Приведено результати вивчення процесів глибокого очищення Cd, Zn та Te при використанні розробленої нами установки з обертовим контейнером із оптичного кварцу шляхом їх дистиляції і перекристалізації. Ця установка є багатофункціональною і дозволяє проводити дистиляцію, зонну очистку, перекристалізацію як у горизонтальному (під невеликим кутом), так і у вертикальному напрямках. Показано, що горизонтальна зонна очистка є ефективною для більшості домішок, за винятком вуглецю. Для очищення Cd, Zn та Te від домішки вуглецю додатково використаний вертикальний варіант зонної очистки, що дозволив знизити вміст вуглецю з 10⁻³ до -10⁻⁶ %

Luminescent properties of ZnSxSe₍₁₋x₎ mixed crystals obtained by solid-phase synthesis and melt-growing

The luminescence characteristics of ZnSxSe₍₁₋x₎ mixed crystals (MC) obtained by solid-phase synthesis and melt-growing were studied. In X-ray luminescence spectra of ZnSxSe₍₁₋x₎ powdered MC synthesized from ZnS and ZnSe powders, where x = 0.90 to 0.99, a non-elementary band with λmax ~ 520 nm (I₁) was observed, but for ZnSxSe₍₁₋x₎ with low concentrations of ZnS (x = 0.05) the luminescence band with λmax = 600-630 nm (I₂) was a dominate. In X-ray luminescence spectra of ZnSxSe₍₁₋x₎ MC (x = 0.05 to 0.3) obtained by the melt growth only I₂ luminescence band with shifted maximum from 610 nm to 590 nm at sulfur concentration increasing was observed. It is shown that for the composition of ZnS₀.₁₅Se₀.₈₅ MC annealed in zinc vapor the light yield of X-ray luminescence is 1.6 times higher than in the commercial ZnSe(Te) crystals. In consideration of this fact it might be supposed, that this MC can find application in scintillation detectors of X-ray and low-energy gamma radiation

Crystals Cd₁₋x ZnxTe – a promising material for non-cryogenic semiconductor detectors: preparations, structure defectness and electrophysical properties

Relationship between preparation conditions of the raw charge, crucible material, growth regimes and structure defectness and electrophysical properties of crystals Cd₁₋x ZnxTe has been studied. The crystals were grown both from the raw material which had been pre-synthesized in quartz ampoules and from the raw material synthesized from the elements directly in the growth furnace. It is shown that the best values of electric resistivity ρ (up to 10¹¹ Ohm⋅cm) and sensitivity to X-ray and gamma-radiation are obtained for crystals grown in crucibles of highly pure coal-graphite material from the pre-synthesized raw charge. Correlation has been established between values of ρ and crystal defectness: decrease of dislocation density by 10⁴ times led to 10⁷ times higher values of resistivity. Concentration of dislocation etching pits regularly decreased with higher purity of the raw material and optimization of crystal preparation technology

Doping methods and properties of the solid solutions on AIᴵᴵBⱽᴵ crystals base

It has been shown that the composition and concentration of complex and radiative recombination centers in solid solution crystals in AIᴵᴵBⱽᴵ systems depends along what section of the concentration triangle is the solid solution obtained. Effects have been studied of the isovalent dopant and thermal treatment in different media upon optico-luminescent, structural and physico-chemical characteristics of solid solution of crystals in the nSe-nTe system.Встановлено, що склад і концентрація комплексних центрів випромінювальної комбінації кристалів твердих розчинів (ТР) у системах AIᴵᴵBⱽᴵ залежать від того, вздовж якого розрізу концентраційного трикутника відбувається утворення ТР. Досліджено вплив ізовалентної домішки і також термообробки у різних середовищах на оптико-люмінесцентні, структурні й фізико-хімічні характеристики кристалів ТР у системі nSe-nTe.Установлено, что состав и концентрация комплексных центров излучательной рекомбинации кристаллов твердых растворов (ТР) в системах AIᴵᴵBⱽᴵ зависят от того, по какому разрезу концентрационного треугольника происходит образование ТР. Исследовано влияние изовалентной примеси и термообработки в различных средах на оптико-люминесцентные, структурные и физико-химические характеристики кристаллов ТР в системе nSe-nTe