Diffusionskonstante und charakteristische Absorption vor der Bandkante von Mn in ZnO-Kristallen
ZnO single crystals were doped with Mn and Co by diffusion. In the temperature range from 1400–1600 K the Mn and Co-diffusion-constants were determined:DMn=3.2 · 10−3 exp (−2.87 eV/kT) cm2 sec−1 andDCo=1·10exp(−3.98 eV/kT) cm2 sec−1.The Mn doped ZnO crystals show a characteristic colour due to an absorption near the intrinsic absorption edge. The corresponding absorption spectra were measured forE⊥c andE∥c. A discussion of different absorption mechanism shows that a charge-transfer transition is responsible for this absorption.