A Temperature Stable Amplifier Characteristics of AlGaN/GaN HEMTs on 3C-SiC/Si

Abstract

A high temperature stable amplifier characteristics for L-band or 2 GHz was studied using AlGaN/GaN high electron mobility transistors (HEMTs) on 3C-SiC/Si substrate. A crack free, high quality AlGaN/GaN heterostructure on a 6-inch Czochralski (Cz)-Si substrate was realized by metal oxide chemical vapor deposition (MOCVD). The epitaxial structure comprises an 8 µm thick nitride layer and a 1 µm thick 3C-SiC intermediate layer. The fabricated AlGaN/GaN HEMT achieved excellent electron transport characteristics along with a comparable cutoff frequency (f T ) of 4.8 GHz for 2 µm gate length device. Temperature dependent S-parameter measurement of open pad structures achieved outstanding temperature stability up to 125°C. Continuous wave power measurements showed a 2 GHz continuous wave power density of 2 W/mm, a maximum power added efficiency (PAE) of 47% along with a linear gain of 17.2 dB for class A amplifier operation. Moreover, at elevated temperature of up to 125°C, the minimal power performance degradation was mainly attributed to the intrinsic property of the device, thus elimination of RF leakage from the buffer or epitaxial layers at high temperatures was confirmed. INDEX TERMSGaN-on-Si HEMT, thick nitride layer, 3C-SiC intermediate layer, high temperature, f T , g m , open pad, P out .

AlGaN/GaN HEMT on 3C-SiC/Low-Resistivity Si Substrate for Microwave Applications

“…The above observation also corroborates with Ref. [26], where it was reported that the temperaturedependent loss evaluation by S-parameter measurements of open pads in sample A showed very good thermal stability for the temperature variation from RT to 125 • C.…”

“…If there was a generation of charge carriers at high temperatures, the g m extracted from S-parameters should have degraded much more than the DC g m . Therefore, we confirm that suppression of RF leakage at high temperatures was successfully attained, which resulting in temperature stability [26].…”

Influence of a thick nitride layer on transmission loss in GaN-on-3C-SiC/low resistivity Si

“…A temperature dependent loss evaluation by S-parameter measurements of open pads confirmed the above fact where the sample with an 8.0 𝜇m thick nitride layer achieved a thermally stable amplifier performance [28,29]. Therefore, it can be confirmed that a thick nitride layer on GaN-on-3C-SiC/LR-Si can effectively minimize transmission loss.…”

“…However, there are no such reports on the effect of nitride layer thickness on the frequency response of transmission loss in GaN-on-3C-SiC/LR-Si. In our previous work, it was reported that a GaNon-3C-SiC/LR-Si structure with a thick nitride layer exhibits very low RF loss by eliminating the low resistivity of Si and also provides better thermal stability [28,29]. However, the characterization of RF loss on metal pads is not sufficient to successfully establish the effect of thick nitride layer on the frequency response of total RF loss.…”

Optimization of MHz Wireless Power Transmission Distance Based on GaN Device

“…Due to its small size and controllable cost, the DC inverter type is widely used in the commercial field of wireless power transmission. The traditional DC inverter MCRWPT technology uses MOSFETs as inverter bridges for DC inverter, and as a result, the system's natural frequency is only below the intermediate frequency, resulting in insufficient system transmission distance and too large system coils [5].…”