Micro-transfer printing of GaN HEMTs on engineered substrates for use in harsh environments

Heterogeneous integration of gallium nitride (GaN) devices is essential to overcome the intrinsic material limitations in advanced electronics. For the successful incorporation of an integration technique into industry, a highly scalable process must be developed. In this work, the heterogeneous integration of GaN high electron mobility transistors (HEMTs) through a micro-transfer printing process is demonstrated. This scalable technique involving HEMTs fabricated on commercially available and CMOS-compatible 8″ GaN on engineered substrate resulted in a high (>95%) transfer success rate and limited device degradation. Transfer was demonstrated to multiple adhesion layers, including copper tape and KMSF 1000 photo-dielectric. The limited degradation that was observed is attributed to a change in stress after transfer, as measured by the Raman spectroscopy. Finally, the viability of the adhesion layer for use in harsh environments was tested. No delamination, significant outgassing, or degradation of electrical properties were observed when the sample was placed under a vacuum or when the temperature was varied between 8 and 473 K. This makes the process an ideal choice for systems intended for space applications.