Abstract Pulsed terahertz emission from the optically excited δ-doped GaAs and GaAs/AlGaAs structures is analyzed by ensemble Monte Carlo simulations. It is found that the amplitude of the transient photocurrent in the δ-doped GaAs structure is slightly lower than the amplitude of the transient photocurrent in the δ-doped GaAs/AlGaAs heterostructure. The evolution of the photoexcited electron–hole plasma on a long time scale after optical pulse is investigated. The results of the simulations show that the recovery rate of the δ-doped GaAs structure after optical pulse significantly exceeds the recovery rate of the δ-doped GaAs/AlGaAs heterostructure. The increased power of the terahertz emission from the δ-doped GaAs structure is expected due to the enhanced recovery rate.