Shirou Ozaki

Collapse-free high power InAlGaN/GaN-HEMT with 3 W/mm at 96 GHz

In this work, we demonstrated an excellent output power (Pout) density of 3.0 W/mm at 96 GHz using a novel collapse-free InAlGaN/GaN-HEMT with an 80-nm gate for a millimeter-wave amplifier. The developed devices showed basic reliability for commercial products. To eliminate the current collapse, a unique double-layer silicon nitride (SiN) passivation film that has oxidation resistance was adopted. We proved the potential of InAlGaN/GaN-HEMT using our unique device technology experimentally and analytically.

Suppression of threshold voltage shift for normally-Off GaN MIS-HEMT without post deposition annealing

In this paper, we present a method of reducing threshold voltage shift for normally-off GaN MIS-HEMT by the optimization of dielectric deposition conditions. High-temperature deposition of Al2O3 insulator decreases the impurities in a dielectric film, leading to small C-V and I-V hysteresis under large positive gate voltage operation. Moreover, Al2O3 deposited at high temperature achieve high quality interface and bulk without post deposition annealing (PDA), preventing the degradation of electrodes and crystallization of insulator film. The fabricated device shows small C-V and I-V hysteresis, with a breakdown voltage of greater than 600 V.

S5-H7: GaN-HEMT technology for high power millimeter-wave amplifier

In this work, we developed (1) an offset-overhanging Y-shaped gate structure to reduce the electric field at gate-edge, and demonstrated (2) low current collapse of InGaN back barrier structure that improved off-state breakdown voltage. In addition, we adopted (3) an InAlN electron-supplying layer to enhance the drain current. The fabricated InAlN/GaN HEMTs with 80-nm gates showed a high off-state breakdown of 73 V, a high drain current of 1.2 A/mm and a high Pout density of 1 W/mm at 90 GHz.

Q-Band InAlGaN/GaN LNA using current reuse topology

A 33 to 41-GHz Low Noise Amplifier (LNA) with a 3-dB Noise Figure (NF) using 0.12-μm InAlGaN/GaN HEMT was developed. The LNA consists of a two-stage common-gate amplifier with current reuse topology in order to obtain a high gain with low power consumption. The developed LNA achieved 15-dB gain, and an input return loss of less than -10 dB. The measured NF was 3 dB, and the power consumption was 280 mW. The measured OIP3 and OP1dB were 24 dBm and 13 dBm at 38 GHz under a supply voltage of 20 V. The chip size of the LNA is 1 × 0.7 mm2.

InAlGaN/GaN-HEMT device technologies for W-band high-power amplifier

We demonstrated an excellent output power (Pout) density performance using a novel InAlGaN/GaN-HEMT with an 80-nm gate for a W-band amplifier. To eliminate current collapse, a unique double-layer silicon nitride (SiN) passivation film with oxidation resistance was adopted. The developed discrete GaN-HEMT achieved a Pout density of 3.0 W/mm at 96 GHz, and we fabricated W-band amplifier MMIC using the air-bridge wiring technology. The Pout density of the MMIC reached 3.6 W/mm at 86 GHz. We proved the potential of the developed InAlGaN/GaN-HEMT experimentally using our unique device technology. With the aim of future applications, we developed a novel wiring-inter-layer technology. It consists of a cavity structure and a moisture-resistant dielectric film technology. We demonstrated excellent high-frequency performances and low current collapse originating in humidity-degradation using AlGaN/GaN-HEMT. This is also a valuable technology for InAlGaN/GaN-HEMT.

Millimeter-wave multi-chip module for GaN MMIC transceivers fabricated using multilayer ceramics technology

This paper presents a multi-chip module (MCM) suitable for GaN monolithic microwave integrated circuit transceivers. The MCM has an embedded heat sink and novel radio frequency interface structure fabricated using multilayer ceramics technology. The novel interface widens the bandwidth and improves insertion loss operating up to millimeter-wave frequencies. A fabricated transceiver MCM occupying only 12 × 36 mm2 is also demonstrated with a GaN power amplifier.

High-Power-Density InAlGaN/GaN-HEMT Technology for W-Band Amplifier

We demonstrated an excellent output power (Pout) density performance using a novel InAlGaN/GaN-HEMT with an 80-nm gate for a high-power W-band amplifier. The developed HEMT showed basic reliability for commercial products. A unique double-layer silicon nitride (SiN) passivation film with oxidation resistance was adopted to suppress current collapse. The developed discrete InAlGaN/GaN-HEMT achieved a Pout density of 3.0 W/mm at 96 GHz, and the Pout density of MMIC reached 3.6W/mm at 86 GHz. We proved excellent potential of developed InAlGaN/GaN-HEMT using our unique device technologies. Furthermore, we suggested the physical advantage of the InAlGaN/GaN-HEMT structure using device simulator.