Czochralski growth techniques of germanium crystals grown from a melt covered partially or fully by liquid B2O3

Abstract

We propose two unique Czochralski (CZ) techniques for growing germanium (Ge) crystals with an extremely low dislocation density and high interstitial oxygen concentration ([Oi]) using boron oxide (B 2 O 3 ) and a silica crucible. When a Ge melt is partially covered with liquid B 2 O 3 , but only on the outer region of the melt surface, germanium-oxide (GeO 2 )-related particles forming naturally in the melt are effectively dissolved by the liquid B 2 O 3 . The clean central portion of the melt produces dislocation-free undoped or Ga-doped Ge crystals. In addition, Ge crystals with [Oi] up to 6  10 17 cm -3 can be grown from a melt fully covered by liquid B 2 O 3 with added GeO 2 powder. The reaction and transportation of oxygen atoms during the growth process using B 2 O 3 was investigated, revealing that liquid B 2 O 3 acts like a catalyst without heavy contamination of the growing Ge crystal by B and Si atoms.

Электрофизические параметры и дефекты структуры Ge, полученного низкоградиентным методом Чохральского / Фрицлер К.Б., Труханов Е.М., Касимкин П.В., Шлегель В.Н., Васильев Я.В.

“…Это позволило повысить устойчивость системы управления, применяя типовые алгоритмы регулирования. Показано, что используемый метод весового контроля позволяет успешно управлять процессом роста германия из-под флюса B 2 O 3, что перспективно для получения бездислокационных кристаллов германия [7]. Исследованы электрофизические характеристики и дефектная структура монокристаллов Ge, выращенных методом LTG Cz из-под флюса.…”

Improved Czochralski Growth of Germanium Single Crystals from a Melt Covered by Boron Oxide

“…The dislocation density in a Ge crystal can be considerably reduced by using the technique described. In addition, no etch pits could be detected in [111] or [100]-oriented Ge crystals [14,15] has an ability to dissolve GeO 2 -related particles, but the interstitial oxygen concentration in a Ge crystal grown from B 2 O 3 -partially-covered melt was not very high. Assuming that dissolved oxygen atoms evaporated from Ge melt surface in the central region of the crucible, several Ge crystals were grown from a melt fully covered by B 2 O 3 liquid in order to avoid such evaporation.…”