High linearity and high-power of composite component graded-AlGaN/graded-InGaN/ GaN HEMTs

In this paper, the compositegraded-AlGaN/graded-InGaN high electron mobility transistors (CG-HEMTs)are reported with high linearity and high power. In order to broadenthe electron distribution, the graded-AlGaN barrier and graded-InGaNchannel layer are combined. Thus, the wider gate voltage swing (GVS) isrealized. At the same time, due to the two graded layers, the centroidof 3DEG in CG-HEMTs is located in the middle of the two graded layers.Thus, the centroid of 3DEG of the CG-HEMTs is kept away from both thehigh Al component and the high In component. The random alloy scatteringof charge carriers is reduced. This is why the mobility of the CG-HEMTsis higher. While the transconductance (g$_{\rm~m}$) ofCG-HEMTs is broadened, the peak g$_{\rm~m}$ of theCG-HEMTs is higher because of the high mobility. In order to achievehigh power, the high Al component graded-AlGaN (40%–0%)is grown to enhance polarization. Ultimately, the 4 V of GVS, 260 mS/mm,and 1370 mA/mm are achieved by the CG-HEMTs. At 3.6 GHz, thełinebreak 6.2 W/mm ofoutput power density (P$_{\rm~out}$) and 55% ofpower-added efficiency (PAE) are realized. The output third-orderintercept point (OIP3) of the CG-HEMTs is 40.9 dBm, which is the highestOIP3 ever reported.