Electron Transfer Infrared Modulator (ETIM)

We present an Electron Transfer Infrared Modulator, (ETIM), where one period of the active region is a doped asymmetric double quantum well, consisting of a wide well and a narrow well, whose intersubband transitions are at different wavelengths. Under electric field, tunneling is used to transfer the electrons within the two coupled wells and therefore change the absorption wavelength. The absorption spectra of the ETIM at different biases show clearly the absorption switch from 10.2 µm to 11.4 µm. Photoluminescence and Photoluminescence Excitation Spectroscopy allows to analyse the charge transfer within the wells with the electric field. Several ETIMs based on the same principle are presented: Monochromatic modulators or switchable photocurrent detectors. The influence of the position of the Si donors in the structure on the transition linewidth is also discussed.