FE INCORPORATION AND PRECIPITATION IN SEMIINSULATING FE-DOPED INP GROWN BY METALORGANIC CHEMICAL-VAPOR-DEPOSITION

We report a systematic study of Fe incorporation in a doping range from 1 x 10(17) cm-3 to 3 X 10(18) cm-3 in InP grown by metalorganic chemical vapor deposition. FeP precipitates are readily observed at a Fe concentration of 1 X 10(17) cm-3 confirming that the Fe solubility limit in InP is below 1 X 10(17) cm-3. For Fe concentrations above 2 X 10(17) cm-3, a nonuniform segregation of dopants results in an oscillating doping profile independent of the growth pressure and growth system used. Cross-sectional transmission electron microscopy studies show FeP precipitate distribution in agreement with the peak Fe concentration profile. For Fe-doped layers incorporated with thin InGaAs or Ga markers, the FeP precipitates are preferentially formed at the heterointerfaces. Although Fe-doped InP films are semi-insulating, conducting channels with a surface density of 10(3) to 10(4) CM-2 are always present. Both the preferential precipitation and the conducting channels may have important implications in device structure design incorporating Fe-doped InP layers.