N-Face GaN/AlGaN HEMTs Fabricated Through Layer Transfer Technology

We present a new method to fabricate N-face GaN/ AlGaN high electron mobility transistors (HEMTs). These devices are extremely promising for ultrahigh frequency applications where low contact resistances and excellent carrier confinement are needed. In this letter, the N-face of a Ga-face AlGaN/GaN epilayer grown on Si(111) is exposed by removing the Si substrate. To provide mechanical support, prior to the substrate removal, the Ga-face of the wafer is bonded to a Si(100) carrier wafer. The resultant N-face GaN/AlGaN heterostructures exhibited record transport properties (mu(e) = 1670 cm(2)/V . s, n(s) = 1.6 x 10(13)/cm(2), and R-sh = 240 Omega/sq). These excellent transport properties rendered N-face HEMTs with 30% higher maximum drain current than Ga-face HEMTs and good RF characteristics (f(T) = 10.7 GHz . mu m and f(max) = 21.5 GHz . mu m), comparable to state-of-the-art Ga-face devices.