Resonant tunneling diodes for room-temperature terahertz oscillators

Our recent results of THz oscillators using GaInAs/AlAs resonant tunneling diodes (RTDs) are reported. For high frequency oscillation, the dwell time in the resonant tunneling structure was reduced by a narrow well, and a fundamental oscillation up to 1.31 THz with the output power of 10 μW was achieved at room temperature. Higher frequency is expected with the structures reducing both of the dwell time and collector transit time. For high output power, coherent power combining was demonstrated in a two-element array, and 610 μW at 620 GHz was obtained. Spectral linewidth of a few megahertz and a frequency change with bias voltage were also obtained. Direct intensity modulation with bias voltage and wireless data transmission were investigated, and a transmission rate of 3 Gbps with the bit error rate of 3×10^-5 was obtained in a preliminary experiment at 540 GHz.