Individual charge traps in the gate stack of gate-all-around field-effect-transistors have been identified from their random telegraph noise (RTN) characteristics in the time and frequency domains. The energy level and depth location of the corresponding charge traps were extracted from capture/emission time constant and corner frequency. The charge traps were determined to be the excited states of oxygen vacancies in the dielectric located 3 nm away from the interface. Both the time domain and frequency domain RTN measurements lead to an identical result.