CS196016B1 - Process for preparing high-pure germanium - Google Patents

Description

SUMMARY OF THE INVENTION The present invention provides a process for preparing single crystals of very pure germanium having an impurity concentration of 7¾-N _and / or less than 5.10 ¹⁰ at / cm ³ , in which germanium of initial purity is exposed to the nuclear particle field, thereby causing nuclear reactions and nuclear compensation, in particular conversion of boron to lithium.

Existing methods of obtaining very pure germanium consist in repeatedly purifying germanium either by band melting, or by repeated drawing of single crystals according to Czchralski, or a combination of both.

The greatest difficulty in zone cleaning or single crystal drawing is the need to minimize pollution of germanium, not only by the impurities that are released from the vessel containing molten germanium, whether it is a quartz or graphite crucible, a quartz or graphite boat or a combination thereof, but also around the container, for example from the walls of the drawing device, the graphite heating element, the temperature ecranes, etc.

Thus, on the one hand, it is necessary to heat-treat germanium on the one hand, for example by zoning or single-crystal drawing, or a combination of both, to increase its purity, but on the other hand, germanium must still be protected by new operations. Thus, the efficiency of the preparation of single crystals of very pure germanium is substantially reduced.

196 016

198,018 '?

The disadvantages of the prior art processes are eliminated by the process according to the invention, in which the germanium of the initial degree of purity is exposed to the field of nuclear particles which cause nuclear reactions and nuclear compensation in the starting material. Nuclear reactions thus cause a change in contamination, such as boron to lithium, which cannot be achieved by conventional technology at all or very difficult. The process according to the invention, on the other hand, achieves a high degree of homogenization at a considerably less laborious and time-consuming process, which allows the preparation of homogeneous crystals of very pure germanium. In this way, a substantially higher technical effect is achieved in a shorter time by means of nuclear reactions and nuclear compensation, possibly in combination with the technologies used hitherto.

Example:

The boron concentration in the polycrystalline starting germanium is 5.10 [mu] t / cm < 3 &gt;. After twenty purification operations by zinc melting or drawing according to Czochralski, the boron concentration is reduced to 5 &lt; 10 &gt; In order to further reduce the concentration to less than atΙΟ θ at / cm 2, a further twenty cleaning operations are required. The same effect is achieved by using the reaction B ¹ ® / n, «</ Li? and germanium purity with less than 10 ^ ° we get already at prg &

campaign. In a similar way, other elements that are polluting the starting germanium can be removed.

Claims (1)

OBJECT OF THE INVENTION Process for preparing single crystals of very pure germanium with the possibility of obtaining a degree of purity, expressed as polluting atomic concentrations below ΙΟ θ at / cn, characterized by subjecting germanium of the initial degree of purity to a nuclear particle field, e.g. Thus, nuclear reactions (n, v) and / or / n, Z (a) and / or (p) are induced in the starting material, and nuclear impregnations are converted, for example, impurities are converted, for example, to lithium.