It has been found that bulk ZnTe crystal can be relatively easily doped
to the hole concentration level of 10¹⁹ cm-3. However, introducing Mn into the ZnTe:P strongly reduces the hole concentration to level of 10¹⁶ cm^-3 due to high degree of compensation. In this communication we report the high pressure and high temperature annealing technique, which enabled one to suppress the compensation and to achieve the hole concentration level as high as 5x10¹⁸ cm^-3.
The (Zn,Mn)Te crystals (0<x<0.09) doped with P to level of 5x10¹⁹ cm^-3 were grown by high pressure Bridgman technique. Despite of heavy doping, as-grown crystals exhibited hole concentration of only 4x10¹⁶ cm^-3 and degree of compensation (K) reached 0.9. In order to suppress the compensation, the as-grown crystals were subjected to annealing in nitrogen atmosphere under a pressure of 4 MPa at T=800⁰ C for a period of one week. After the annealing, K reduced to 0.1 and the hole concentration increased to 5x10¹⁸ cm-3. We suggest that the high K in the as-grown (Zn,Mn)Te:P is connected with interstitial Mn²⁺ ions, which act as double compensating donors. The high pressure annealing transfers the Mn interstitials into random precipitates reducing the concentration of compensating donors. This rearrangement of Mn atom sites is responsible for the reduction in K and an accompanying increase in the hole concentration.