Low contact resistance and high breakdown voltage of AlGaN/GaN HEMT grown on silicon using both AlN/GaN superlattice and Al 0.07 Ga 0.93 N back barrier layer

In this study, the growth of a high-quality AlGaN/GaN high electron mobility transistor (HEMT) heterostructure on silicon (Si) by metal–organic chemical vapor deposition was investigated by utilizing both the AlN/GaN superlattice (SL) and Al 0.07 Ga 0.93 N back barrier (BB) techniques. An atomic force microscope and high-resolution x-ray diffractometer confirm a low surface roughness of 0.26–0.34 nm and the formation of a high-quality AlN/GaN SL and GaN channel. The AlGaN/GaN heterostructures exhibit a high electron mobility of up to 1700 cm 2 V −1 ∙s and a high carrier concentration density of (1.02–1.06 × 10 13 cm −2 ) for both heterostructures. The AlGaN/GaN HEMT devices demonstrate a low specific contact resistivity ( ρ c ) of 2.7 × 10 −6 Ω·cm 2 and a low contact resistance ( R C ) of 0.3 Ω·mm for the heterostructure with a BB layer. Furthermore, the DC characteristics demonstrate that incorporating Al 0.07 Ga 0.93 N BB in the heterostructure results in a 19.2% increase in lateral breakdown voltage (with a 10 µ m spacing) and a 27.5% increase in vertical breakdown voltage (at 1 mA cm −2 ) compared to heterostructures without Al 0.07 Ga 0.93 N BB within the AlN/GaN SL structure. Moreover, an improvement of 10.6% in the maximum saturation current ( I DS ) and 15.2% in on-resistance ( R ON ) has been achieved for the device fabricated on an Al 0.07 Ga 0.93 N BB structure. The insertion loss of the buffer layer improves to −1.40 dB mm −1 at 40 GHz. Consequently, the proposed heterostructure investigated in this study demonstrates suitability for electronic device applications.