The energy distribution and concentration of electrically active background impurities in GaP have been investigated by observing the current when space charge trapped at these impurities is thermally released within the depletion region of a Schottky barrier formed on the semiconductor. Large‐area Schottky barriers are used for these measurements in order that small concentrations of impurities may be detected. The measurements have been carried out for both liquid‐encapsulated‐Czochralski (LEC)‐ and liquid‐phase‐epitaxial (LPE)‐grown material usingn‐type wafers. In LEC GaP, at least seven electrically active background levels are detectable and these exist at concentrations between 1 × 1015−3 × 1016cm−3, while in LPE GaP only three or four are detectable and these exist in much smaller concentrations of about 1014cm−3.