Electron-paramagnetic-resonance spectra in as-grown CdGeAs2

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Abstract
Electron‐paramagnetic‐resonance (EPR) has been used to investigate point defects in a single crystal of as‐grown CdGeAs2. Spectra taken at 17 K with the magnetic field parallel to the c axis show a broad signal (∼165 Gauss wide) centered on gc=2.018 and a sharper signal (∼56 G wide) centered on gc=2.015. Together, these signals represent an unpaired‐spin concentration of approximately 5×1019 cm−3. A single broad signal (∼165 G wide) centered on ga=1.995 is observed at 17 K when the magnetic field is along the a axis. It is suggested that these dominant EPR‐active defects in CdGeAs2 consist of either a cation vacancy or an antisite cation with the unpaired spin shared by the four neighboring As ions. Additional weak EPR lines appear when the temperature is increased (from 17 to 40 K) and the microwave power is decreased (from 7 to 2.3 mW).