Low contact resistance and high breakdown voltage of AlGaN/GaN HEMT grown on silicon using both AlN/GaN superlattice and Al0.07Ga0.93N back barrier layer

Abstract

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 (MOCVD) was investigated by utilizing the both AlN/GaN superlattice (SL) and Al0.07Ga0.93N back barrier (BB) techniques. Atomic force microscope (AFM) and high-resolution x-ray diffractometer (HR-XRD) confirm low surface roughness of 0.26 – 0.34 nm and the formation of high-quality AlN/GaN SL and GaN channel. The AlGaN/GaN heterostructures exhibit high electron mobility of up to 1700 cm2/V∙s and high carrier concentration density of (1.02 – 1.06 × 1013 cm-2) for both heterostructures. The AlGaN/GaN HEMT devices demonstrate low specific contact resistivity (c) of 2.7 × 10-6 Ω·cm2 and low contact resistance (RC) of 0.3 Ω·mm for the heterostructure with BB layer. Furthermore, the DC characteristics demonstrate that incorporating Al0.07Ga0.93N BB in the heterostructure results in a 19.2% increase in lateral breakdown voltage (with a 10 µm spacing) and a 27.5% increase in vertical breakdown voltage (at 1 mA/cm2), compared to the heterostructure without Al0.07Ga0.93N BB within the AlN/GaN SL structure. Moreover, improvement of 10.6% in maximum saturation current (IDS) and 15.2% in on-resistance (RON)has been for the device fabricated on Al0.07Ga0.93N BB structure. The insertion loss of the buffer layer improves to –1.40 dB/mm at 40 GHz. Consequently, the proposed heterostructure investigated in this study demonstrates suitability for electronic device applications.