Reactive sputtering of III-N materials for applications in electronic devices

Gallium Nitride (GaN) and other III-N semiconductors are rapidly gaining importance in high power and high frequency electronic applications. III-N material based devices are fabricated on heterostructures that are usually grown by high vacuum techniques such as metal-organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). However, in many applications, it is necessary to regrow thin cap layers of III-N materials during device fabrication. One such application is regrowth of ohmic contacts to III-N devices. Heavily doped n(+) GaN, or InGaN grown by MBE or MOCVD is used to obtain low resistance non-alloyed ohmic contacts to GaN based devices. However, from a commercial point of view, this becomes difficult because of the high cost and lack of availability of ultra high vacuum (similar to 1x10(-10) Torr) techniques in most clean room facilities. Reactive sputtering provides a cheaper and more ubiquitous alternative for the growth of thin cap layers on parent MOCVD III-N heterostructures during device fabrication. In this work, we explore the possibility of using reactive sputtering as a method to grow III-N materials as ohmic contacts to GaN based devices.