High linearity AlGaN/GaN HEMT with double-V th coupling for millimeter-wave applications

We demonstrated an AlGaN/GaN high electron mobility transistor (HEMT) namely double- V th coupling HEMT (DVC-HEMT) fabricated by connecting different threshold voltage ( V th ) values including the slant recess element and planar element in parallel along the gate width with N 2 O plasma treatment on the gate region. The comparative studies of DVC-HEMT and Fin-like HEMT fabricated on the same wafer show significantly improved linearity of transconductance ( G m ) and radio frequency (RF) output signal characteristics in DVC-HEMT. The fabricated device shows the transconductance plateau larger than 7 V, which yields a flattened f T / f max -gate bias dependence. At the operating frequency of 30 GHz, the peak power-added efficiency (PAE) of 41% accompanied by the power density ( P out ) of 5.3 W/mm. Furthermore, the proposed architecture also features an exceptional linearity performance with 1-dB compression point ( P 1 dB ) of 28 dBm, whereas that of the Fin-like HEMT is 25.2 dBm. The device demonstrated in this article has great potential to be a new paradigm for millimeter-wave application where high linearity is essential.