Aligned Carbon Nanotube-Based Terahertz Flexible Diodes for Frequency Conversion and Phase Shift at Millimeter Wave Band

Although there have been remarkable breakthroughs in flexible electronics, the working speed of flexible devices is still relatively slow compared to that of rigid substrates. Furthermore, the frequency gap between the sensed physiological signal and the wireless communication carrier wave has been enlarged with the advancement of wireless communication technology. Here, based on advantages of the aligned carbon nanotube (ACNT), we developed devices on polyimide (PI) substrates with an intrinsic cutoff frequency (<i>f</i>_c) of more than 300 GHz and into the THz region. Furthermore, frequency mixers and phase shifters built by ACNT-based diodes are demonstrated with conversion gain ranging from -11.5 to -18 dB and output maximum relative phase shifting of 55° having average insertion loss of about 3.9 dB. All performances were achieved from flexible devices working at a mmWave band from 30 to 40 GHz, and for the first time, they were comparable to that built by active transistors from conventional semiconductors.