Comparison of AlGaN/GaN MSM Varactor Diodes Based on HFET and MOSHFET Layer Structures
English
Marso, Michel[Institute of Bio- and Nanosystems (IBN1) and cni—Center of Nanoelectronic Systems for Information Technology, Research Centre Jülich, 52425 Jülich, Germany]
Fox, A.[Institute of Bio- and Nanosystems (IBN1) and cni—Center of Nanoelectronic Systems for Information Technology, Research Centre Jülich, 52425 Jülich, Germany]
Heidelberger, G.[Institute of Bio- and Nanosystems (IBN1) and cni—Center of Nanoelectronic Systems for Information Technology, Research Centre Jülich, 52425 Jülich, Germany]
Kordoš, P.[Institute of Electrical Engineering, Slovak Academy of Sciences, SK-84104 Bratislava, Slovak Republic]
Lüth, H.[Institute of Bio- and Nanosystems (IBN1) and cni—Center of Nanoelectronic Systems for Information Technology, Research Centre Jülich, 52425 Jülich, Germany]
[en] In this letter, the performance of AlGaN/GaN-based metal–semiconductor–metal (MSM) varactor diodes based on HFET and MOSHFET layer systems is investigated. Passivated HFET MSM devices are coated with a 10-nm-thick SiO2 layer between the electrodes; in MOSHFET-based diodes, this layer is also used as an insulator underneath the gate. Device fabrication uses standard HFET fabrication technology, allowing easy integration in monolithic microwave integrated circuits. Devices with different electrode geometry are characterized by direct current and by S-parameter measurements up to 50 GHz. The HFET-based varactors show capacitance ratios up to 14 and cutoff frequencies up to 74 GHz. The MOSHFET-based devices, on the other hand, show lower capacitance ratios and poorer stability because of the insulation layer between electrodes and semiconductor.
[Institute of Bio- and Nanosystems (IBN1) and cni—Center of Nanoelectronic Systems for Information Technology, Research Centre Jülich, 52425 Jülich, Germany]
