TERAHERTZ RESPONSE OF RESONANT-TUNNELING DIODES

We have measured the broad-band terahertz response of state of the art InGaAs/AlAs and InAs/AlSb resonant tunneling diodes from 180 GHz to 3 .6 THz using the free-electron lasers at UCSB. A tungsten whisker ante nna in a conventional probe station is used to couple the far-infrared radiation into the device. Normalizing the resonant tunneling respons e with the off-resonant response allows us to circumvent the much slow er RC time constant of the device and consequently enables a measureme nt of the relaxation time due to the quantum inductance.