Overcoming the poor crystal quality and DC characteristics of AlGaN/GaN/AlGaN double-heterostructure high electron mobility transistors

We report Al0.30Ga0.70N/GaN/Al0.07Ga0.93N double-heterostructure high electron mobility transistors (DH HEMTs) with admirable DC characteristics fully surpassing those of the Al0.30Ga0.70N/GaN single-heterostructure (SH) HEMTs. The DH HEMTs feature a 1400-nm graded AlxGa1-xN (x = 0-0.06) buffer layer, a 300-nm Al0.07Ga0.93N back barrier layer, and a 70-nm thick GaN channel layer. Due to the improved cystal quality and enhanced confinement of the carriers, the DH HEMTs presented have shown improved performance with respect to the conventional SH HEMTs, including electron mobility promoted from 1701 to 1744 cm(2) V-1 s(-1), surface roughness in terms of root mean square values (RMS) reduced from 0.19 to 0.16 nm, (10-12) full widths at half-maximum (FWHMs) reduced from 726 to 540 arcsec, subthreshold swing (SS) reduced from 113 to 78 mV dec(-1), I-on/I-off ratio increased from 10(5.3) to 10(6.2), drain-induced barrier lowering (DIBL) reduced from 24 and 14 mV V-1, and breakdown voltage promoted from 59 to 109 V. (C) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim