Record low contact resistance for InAlN/GaN HEMTs on Si with non-gold metal
Ng, Geok Ing
Kumar, Chandra Mohan Manoj
Foo, Siew Chuen
Ang, Kian Siong
Dolmanan, Surani Bin
Date of Issue2015
School of Electrical and Electronic Engineering
We have demonstrated 0.17-µm gate-length In0.17Al0.83N/GaN high-electron-mobility transistors (HEMTs) on Si(111) substrates using a non-gold metal stack (Ta/Si/Ti/Al/Ni/Ta) with a record-low ohmic contact resistance (Rc) of 0.36 Ω mm. This contact resistance is comparable to the conventional gold-based (Ti/Al/Ni/Au) ohmic contact resistance (Rc = 0.33 Ω mm). A non-gold ohmic contact exhibited a smooth surface morphology with a root mean square surface roughness of ~2.1 nm (scan area of 5 × 5 µm2). The HEMTs exhibited a maximum drain current density of 1110 mA/mm, a maximum extrinsic transconductance of 353 mS/mm, a unity current gain cutoff frequency of 48 GHz, and a maximum oscillation frequency of 66 GHz. These devices exhibited a very small (<8%) drain current collapse for the quiescent biases (Vgs0 = −5 V, Vds0 = 10 V) with a pulse width/period of 200 ns/1 ms. These results demonstrate the feasibility of using a non-gold metal stack as a low Rc ohmic contact for the realization of high-frequency operating InAlN/AlN/GaN HEMTs on Si substrates without using recess etching and regrowth processes.
Japanese journal of applied physics
© 2015 The Japan Society of Applied Physics. This is the author created version of a work that has been peer reviewed and accepted for publication by Japanese journal of applied physics, The Japan Society of Applied Physics. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [http://dx.doi.org/10.7567/JJAP.54.04DF12].