Fabrication and characterization of a high-electron-mobility transistor using a sputtering buffer layer on a Si substrate

Abstract

A high-electron-mobility transistor (HEMT) was developed using a high-purity gallium nitride (GaN) sputtering target (oxygen content of <0.4% and metal impurities of 99.999% (5 N)). Two layers of sputtered GaN/aluminum nitride (AlN) were used instead of conventional superlattices (SLs) as stress-relaxing structures in GaN on Si devices. AlGaN/GaN layers were deposited on the GaN/AlN/Si templates by metal–organic chemical vapor deposition to construct a channel of HEMTs. To the best of our knowledge, this is the first demonstration of HEMTs without SLs achieved using sputtered GaN/AlN buffer layers, instead of normal buffer layers obtained via chemical vapor deposition on Si substrates. Sputter epitaxy has a significant potential for fabricating low-cost and high-producibility GaN-on-Si devices.