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 $8~\mu \text{m}$ thick nitride layer and a $1~\mu \text{m}$ thick 3C-SiC intermediate layer. The fabricated AlGaN/GaN HEMT achieved excellent electron transport characteristics along with a comparable cutoff frequency ( ${f}~_{\text {T}}$ ) of 4.8 GHz for $2~\mu \text{m}$ gate length device. Temperature dependent S-parameter measurement of open pad structures achieved outstanding temperature stability up to $125~^\circ \text{C}$ . 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 $125~^\circ \text{C}$ , 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.
Highlights
In the field of high power and high frequency semiconductor device technologies, gallium nitride (GaN) has emerged as one of the most promising candidates for the past decades because of its high breakdown field and the high electron saturation velocity [1]–[3]
For RF applications of GaN high electron mobility transistors (HEMTs), typically SiC substrates are used owing to its certain advantages, such as high thermal conductivity and very low lattice mismatch to GaN [5], [6]
In the case of high-resistivity Si (HR-Si), the intrinsic carrier density significantly increases at high temperature and these carriers generate huge RF loss [19]
Summary
In the field of high power and high frequency semiconductor device technologies, gallium nitride (GaN) has emerged as one of the most promising candidates for the past decades because of its high breakdown field and the high electron saturation velocity [1]–[3]. At high temperature, there is a possibility of generation of charge carriers in the buffer layers for GaN devices on low resistivity (LR-Si)
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