Mobility and charge density tuning in double δ-doped pseudomorphic high-electron-mobility transistors grown by metal organic chemical vapor deposition

In this article, the authors present mobility and charge density tuning for metal organic chemical vapor deposition (MOCVD)-grown double δ-doped pseudomorphic high-electron-mobility transistors (PHEMTs). Good epitaxial wafers were obtained by MOCVD as indicated by uniform and abrupt interfaces seen in measurements taken using a transmission electron microscope and two pronounced Si-δ-doped peaks in the secondary ion mass spectrometry analysis. The 1-μm-gate-length PHEMT device exhibited good dc performance with a threshold voltage of −1.34V, a maximum drain current of 570mA∕mm, and a maximum transconductance of 279mS∕mm. From the dependences of mobility and charge density between the δ-doping level and spacer layer thickness, most PHEMT design requirements in the ranges between 5750 and 7500cm2∕Vs (for mobility) and 2.4×1012 and 3.6×1012cm−2 (for charge density) can be satisfied.