Terahertz Response of Zero-Dimensional States in Resonant-Tunneling Diodes

The photoresponse of zero-dimensional states in double barrier resonant tunneling diodes has been observed using high intensity THz radiation (photon frequencies ranging from 4 to 10 THz) from a free-electron laser. The double barrier resonant tunneling diodes have silicon donors in the quantum well which act as individual localized tunneling channels. The high frequency response of these diodes shows additional features due to the presence of these extra channels. The temperature dependence allows us to identify the contribution of the zero-dimensional states. The absence of wavelength dependence in the observed photoresponse indicates that photoassisted tunneling does not occur under these measurement conditions. (C) 1995 American Institute of Physics.