Single crystal of compound semiconductor of groups III-V with low dislocation density.

摘要

More than two impurities are doped in a host crystal of compound semiconductors. One of the impurities is an anisoelectronic impurity. One or more than one impurities are isoelectronic impurities. Anisoelectronic impurity determines the electronic property and the carrier density of the semiconductor. lsoelectronic impurity does not change the electronic property. But isoelectronic impurity has an effect of impurity hardening.

The impurity atom forms a covelent bond with a host atom. The bond length between an impurity and a host atom differs from the standard bond between host atoms. Although the real bond lengths between an impurity atom and a host atom cannot measured, the Inventor think the difference of bond lengths generate dislocation or other lattice defects of crystal. The real bond length "A" between an impurity and a host atom in an impurity-doped crystal may be surmised from the corresponding bond length "a" or "b" in a two-component crystal consisting of the impurity element and the host element.

Definite and measurable bond length "a" or "b" replaces the real unknown bond length "A". The impurity whose replaced bond length "a" or "b" is larger than the standard bond length "a<Sub>o</Sub>" between host atoms is called an over-impurity. The impurity whose replaced bond length "a" or "b" is smaller than "a<Sub>o</Sub>" is called an under-impurity. At least one under-impurity and at least one over-impurity must be doped. And the arithmetic average "a" of the bond lengths between the impurity atoms and the host atoms should not differ from "a<Sub>o</Sub>" by more than 1 %. Size effects of under- and over- impurities compensate each other in the double-impurity-doped crystal. Dislocations or other lattice defects are reduced.