Max-Planck-Inst. Festkoerperforsch., Stuttgart , Fed. Rep. Ger.

The anomalously deep and nondegenerate ground state of Ge donors in GaP is better described as a deep state attached to higher X-min. of the conduction band than as a shallow one attached to the abs. min. This is because of a very strong intervalley interaction between the higher min. at X for point-charge impurities located at the cation site.
 

Proc. Int. Conf. Phys. Semicond., 15th.