Ferromagnetic Ga1-xMnxAs films containing up to 5.1 at%Mn were grown by low-temperature MBE. The structural, electrical, and magnetic properties of the layers are reported. At x > 0.01, the materials show a ferromagnetic behavior. The Curie temperature reaches 80 K at 5.1at% Mn. We propose the use of a n+-GaAs/p+-GaMnAs Esaki-diode (ferromagnetic Esaki-diode, FED) to provide injection of spin-polarized electrons via interband tunneling. Under reverse bias, spin-polarized electrons at the Fermi level in the valence band of GaMnAs tunnel to the conduction band of GaAs in contrast to the injection of spin-polarized holes used before.