Reversible variation of donor concentrations in high-purity InP by thermal treatment

The donor concentration in high-purity InP bulk crystals was found to be reversibly changed by thermal treatment. At a level of 0.5-2.0x10(15) cm(-3), the concentration decreased below 340 degrees C and increased above 380 degrees C. Far-infrared photoconductivity measurements revealed that shallow donors with a binding energy of similar to 7.5 meV were made to disappear and appear by low and high temperature treatment, respectively. Two possible mechanisms responsible for these phenomena are discussed in connection with the extrinsic and intrinsic donor origin. One probable mechanism is that shallow extrinsic donors, assigned to Si, are electrically passivated by some kind of defect, such as atomic hydrogen, and reactivated by low and high temperature treatment, respectively. (C) 2000 American Institute of Physics. [S0021-8979(00)01606-6].