Reduction of grown-in dislocation density in Ge Czochralski-grown from the B2O3-partially-covered melt

Czochralski-growth of germanium crystals containing high concentrations of oxygen impurities

“…<111> oriented Ge crystals, 1 inch in diameter, were grown by the CZ method at a pulling rate of 10 mm/h under an Ar gas flow of 1 liter/min at 1 atm. Detailed growth conditions were described previously [3]. For comparison, a Ge crystal was grown from a Ge melt under the same growth conditions but without any B 2 O 3 liquid.…”

“…The dislocation density in wafers cut from the top portion of the crystal was evaluated by observing etch pits at five different positions (center, r/2: r is radius of wafers) using optical microscopy after preferential etching using Billig etchant [10] at 85˚C for 3 min. Detailed conditions were described previously [3].…”

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

“…In the case of Ge, a similar phenomenon produced by oxygen doping was recently reported [15], and application in solar cells and other electric devices using such Ge crystals with high mechanical strength is expected in the near future. [19]. No particles to hinder dislocation-free crystal growth were observed in the melt.…”

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

“…Detailed growth conditions were as described previously [14]. After melting the B 2 O 3 and Ge, only the outside region of the Ge melt was partially covered with the liquid B 2 O 3 , and a clean and particle-free Ge melt surface was produced in the central region of the crucible.…”

“…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.…”