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Keywords:

  • degenerate layer;
  • donor activation energy;
  • Hall effect;
  • MgZnO thin films;
  • phosphorus doping;
  • pseudomorphic growth

Abstract

Phosphorus-doped MgxZn1−xO thin films with various Mg content (0.07 ≤ x ≤ 0.28) and up to 0.7 at% P were grown on ZnO(000-1) single crystals by pulsed laser deposition (PLD). In dependence on the dopant concentrations, tensile or compressively strained, in-plane lattice matched, i.e., pseudomorphic growth of the MgZnO:P films was confirmed by high-resolution X-ray diffraction (HR-XRD). All investigated, high-quality MgZnO:P films are n-type, also after post-growth annealing at 850 °C. From the Hall analysis the activation energy of the dominating donors was derived, yielding values of up to 345 meV for high oxygen partial pressure during growth, and shallow donors with an activation energy of about 30 meV for low oxygen pressure. The Hall-mobility of the MgxZn1−xO:P films at a temperature of 65 K was as high as 740 cm2/Vs, and reached values up to 190 cm2/Vs at room temperature, close to the best values reported for bulk ZnO.