Fabrication and nonlinear characterization of GaN HEMTs on SiC and sapphire for high-power applications

Abstract

In this work, we present the characterization results for several HEMT GaNbased devices developed by SELEX Sistemi Integrati. Due to the wide band-gap properties of this material, these devices are very well-suited for high-power applications, and must be characterized under strongly nonlinear and high-power conditions. An extensive power characterization of devices fabricated on GaN grown either on SiC or sapphire substrates is carried out, including pulsed I-V, power sweeps, and load-pull measurements in different bias conditions from class A to class B. An active load-pull bench optimized for high-voltage and high-power measurements allows the load-pull characterization to be extended to the whole Smith chart and the optimum loads to be localized, even for devices with almost reactive optimum terminations. The characterization procedure is performed on HEMT devices fabricated with different technologies and different layouts, in order to improve and refine the fabrication methodology and verify the scaling rules and the effects of defects and thermal degradation. SELEX SI devices show a growing maturity, with performances comparable to state-of-the-art technology.

3.5 GHz WiMAX GaN doherty power amplifier with second harmonic tuning

“…GaN FET devices grown on SiC substrates represent at present a promising solution for the development of RF PAs. In fact, thanks to GaN favorable electrical behavior in terms of current density, breakdown voltage, and cut‐off frequency, and to the remarkable thermal characteristics of the SiC substrate [ 18, 19], GaN‐based power modules handling tens of Watts, up to the X‐band and beyond, can be realized. In this framework, we present a high‐efficiency 21.5 W Doherty PA designed for WiMAX at 3.5 GHz.…”

GaN Monolithic Power Amplifiers for Microwave Backhaul Applications

“…Regarding the technology, in parallel to the reference choice of gallium arsenide (GaAs), which is cheap, mature and available from many suppliers, Gallium Nitride (GaN) integrated technology is attracting a lot of interest at research level, especially for power applications, thanks to its superior characteristics in comparison to GaAs [4][5][6], mainly in terms of power density. Focusing on PAs, this technology leads to lower size and better power dissipation (when using SiC substrate), favourable input and output matching impedances, all features positively affecting overall losses, and eventually efficiency [7].…”

Two-dimensional device simulation for radio frequency performance of AlGaN/GaN HEMT

“…AIGaN/GaN high mobility transistor (HEMT) is a promising candidate for replacing traditional devices in high-frequency, high-power, and high-temperature electronic devices owing to the fact that AIGaN/GaN HEMT has high sheet carrier density, high breakdown voltage, and high saturation current [1][2][3][4]. Moreover, the current-gain cutoff frequency fT of AIGaN/GaN HEMTs is much higher than that of the conventional devices due to its excellent carrier transport properties.…”