Normally-off GaN transistors for power applications

Normally-off high voltage GaN-HFETs for switching applications are presented. Normally-off operation with threshold voltages of 1 V and more and with 5 V gate swing has been obtained by using p-type GaN as gate. Different GaN-based buffer types using doping and backside potential barriers have been used to obtain blocking strengths up to 1000 V. The increase of the dynamic on-state resistance is analyzed for the different buffer types. The best trade-off between low dispersion and high blocking strength was obtained for a modified carbon-doped GaN-buffer that showed a 2.6x increase of the dynamic on-state resistance for 500 V switching as compared to switching from 20 V off-state drain bias. Device operation up to 200 °C ambient temperature without any threshold voltage shift is demonstrated

Mikrosystembausteine fuer Hochtemperaturanwendungen. Hochtemperaturstabile Elektronik auf der Basis von GaAs Abschlussbericht

SIGLEAvailable from TIB Hannover: F96B1210+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

S-Band AlGaN/GaN Power Amplifier MMIC with over 20 Watt Output Power

This paper presents the design of an S-band HPA MMIC in AlGaN/GaN CPW technology for radar TR-module application. The trade-offs of using an MMIC solution versus discrete power devices are discussed. The MMIC shows a maximum output power of 38 Watt at 37% Power Added Efficiency at 3.1 GHz. An output power of more than 20 Watt has been simulated from 2.5 to 3.7 GHz. The robustness against high output VSWR values up to 4:1 has been checked and simulations show a maximum drain-gate voltage of around 60 V

GaInP-Leistungs-HBTs fuer Mobilkommunikation Abschlussbericht

SIGLEAvailable from TIB Hannover: F01B357+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Degradation of AlGaN/GaN high-electron mobility transistors in the current-controlled off-state breakdown

We investigate degradation mechanisms in AlGaN/GaN HEMTs which were repeatedly driven into the current-controlled off-state breakdown or subject to 60 s voltage- or current-controlled off state stresses. The current-controlled sweep in to the breakdown allows the sustainability of breakdown that can not be observed in the voltage controlled sweep. Only temporal changes were observed in the HEMT dc performance after repetitive sweeps, which were explained by charging/discharging of the HEMT surface at the gate-to-drain access region and in the GaN buffer below the gate. Similar changes were observed also if high-voltage stress has been applied on the drain; however, permanent degradation appears after 60 s current-controlled breakdown stress. In this case, the drain leakage current, as well as the breakdown current, increases significantly. On the other hand, the breakdown voltage, as well as the gate characteristics, remains unaltered. We suggest that the avalanche-injection process is governing the off-state breakdown event with a dominant role of the potential barrier at the channel-buffer interface. (C) 2014 AIP Publishing LLC

Characterization Of Gan-Based Single- And Double-Heterostructure Devices

This work focuses on a comparison of two GaN high-electron mobility transistors (HEMTs) epilayer structures, a single- (SH) and a double-heterostructure (DH). DC and pulsed tests reveal lower ID and Ileak in DH devices. Kink effect is also reported; none shows relevant current collapse. DH HEMTs show a much higher breakdown voltage (VBR) and slope. Off-state step-stresses confirm good reliability for these devices thanks to improved back-barrier confinement; SH suffers from punch-through resulting in premature breakdown

Pre-breakdown current fluctuations and RTS noise in reverse-bias-stressed AlGaN/GaN HEMTs

In this contribution we investigate in time domain pre-breakdown current fluctuations during the device degradation between Vcrit ( 48 -50V for -2V/2min step-stress) and the breakdown voltage (Vbd 48 80V), as well as post-stress random telegraph signal (RTS) noise in Al0.24Ga0.76N(25nm)/GaN(40nm UID + 3\u3bcm C-doped)/SiC HEMTs from FBH