GaAs/AlAs triple-quantum-well samples were grown by molecular beam epitaxy, and the middle GaAs quantum-well layer was delta-doped at the well centre with Be shallow acceptors. Then the far-infrared Teraherz prototype emitter was fabricated using the samples. Electroluminescence (EL) and current-voltage characteristics (I-V) were measured at 4.5 K. In the EL spectrum, a wide peak was observed clear 222 cm-1, which is attributed to the Be acceptor’s radiative transitions from the excited odd-parity states to the ground state. Nevertheless, the emission signal was weakened by non-radiative relaxation processes. In the I-V curve, the negative differential resistance characteristic at the position of 0.72 and 1.86 V was also observed clearly. This is attributed to the resonant tunneling between Be acceptor 1s3/2(Γ6+Γ7) energy level in the middle quantum-well and the HH1 band in the left-side non-doping quantum-well, as well as the resonant tunneling between the HH band in the right-side non-doping quantum-well and Be acceptor 2p5/2(Γ6+Γ7) energy level.