Characterization of MBE grown DyP/GaAs and DyAs/GaAs is reported. DC characterization, including I-V and C-V measurements, was performed at different temperatures from 25 to 200/spl deg/C. High frequency characterization of DyP/GaAs Schottky diodes was also performed by measuring the scattering parameters (S parameters) as a function of frequency. A cut-off frequency of close to 2.5 THz was determined from the equivalent circuit parameters for the Schottky diodes having an area of 10 /spl mu/m/sup 2/. DyP is lattice matched to GaAs, with a room temperature mismatch of less than 0.01% and is stable in air with no sign of oxidation, even after months of ambient exposure. High quality DyP and DyAs epilayers were consistently obtained for growth temperatures ranging from 500 to 600/spl deg/C with growth rates between 0.5 and 0.7 /spl mu/m/hr. DyP epilayers are n-type with electron concentrations of 3/spl times/10/sup 20/ to 4/spl times/10/sup 20/ cm/sup -3/ room temperature mobilities of 250 to 300 cm2/V/spl middot/s, and a barrier height of 0.81 eV to GaAs. DyAs epilayers are also n-type with carrier concentrations of 1/spl times/10/sup 21/ to 2/spl times/10/sup 21/ cm/sup -3/, and mobilities between 25 and 40 cm/sup 2//V/spl middot/s.