A STUDY OF P-TYPE DOPING FOR ALGAINP GROWN BY LOW-PRESSURE MOCVD

Doping characteristics for Mg (and Zn) in (AlxGa1-x)0.5In0.5P have been studied with a view towards applying Mg (or Zn) doped AlInP to DH lasers. The solubility limits for the dopants decreased with increasing Al composition. The maximum hole concentration of Zn doped AlInP was at most 2×1017 cm-3, which is too low for practical use in DH lasers. The solubility limits for Mg were several times higher than those for Zn. The maximum hole concentration of Mg doped AlInP was 1×1018 cm-3. The Mg incorporation was considered to be limited by Mg revaporization from the growth surface. The Mg incorporation at a constant doping-source introduction in AlGaInP increased with increasing Al composition. The proportion of electrically active Mg to total incorporated Mg (electrical activity) does not change markedly with Al composition. The Mg electrical activity was quite low even at low doping levels.