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JaeYeobShim,HyungSupYoon,SungJinKim,JuYeonHong,WooJinChang,DongMinKang,JinHeeLee,KyungHoLee 한국물리학회 2002 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.41 No.4
In this paper, we report a highly selective wet gate recess process using a succinic-based solution for fabricating InGaAs/InAlAs/GaAs metamorphic HEMTs (MHEMT). We developed the wet gate recess process using a solution of succinic acid and H$_2$O$_2$ to selectively etch the heavily doped-InGaAs ohmic layer over an InAlAs Schottky layer. The etch rate of the InGaAs layer was about 120 nm/min, and an etch selectivity of the InGaAs to the InAlAs layer higher than 100 was obtained. The 0.2-$\mu$m GaAs-based MHEMT devices were fabricated using the wet gate recess process. The wet-recessed, 0.2$\times$100 $\mu$m MHEMT devices showed DC output characteristics having a high gate-to-drain breakdown voltage of $-$7.6 V, an extrinsic transconductance ($g_{m.max}$) of 700 mS/mm, and a threshold voltage ($V_{th}$) of $-$0.95 V. The wet recessed MHEMT showed good pinch-off characteristics and exhibited good DC uniformities across a 4-inch GaAs wafer having a $V_{th}$ uniformity of 7.4 \% and an extrinsic transconductance of 4.6 \%. The $f_T$ and $f_{max}$ obtained for a PHEMT device were 115 GHz and 230 GHz, respectively.
Jae Yeob Shim,Byeong Ok Lim,Dong Hoon Shin,Hae Cheon Kim,Hyung Sup Yoon,Jin Hee Lee,Jin Koo Rhee,Ju Yeon Hong,Kyoung Ik Cho,Sung Chan Kim 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.44 No.1
The noise performance of 0.15 m GaAs power metamorphic high electron mobility transistor (MHEMT) devices with a double-doped In0:52Al0:48As/In0:53Ga0:47As structure has been investigated together with the DC and microwave characteristics. The 0.15 100 m2 MHEMT device shows a high gate-to-drain breakdown voltage of ..8.3 V, an extrinsic transconductance of 740 mS/mm, and a threshold voltage of ..0.97 V. The obtained cut-o frequency and maximum frequency of oscillation are 133 GHz and 235 GHz, respectively. A very low minimum noise gure of 1.11 dB and an associated gain of 9.51 dB at 30 GHz are obtained for the power MHEMT with an In content of 53 % in the InGaAs channel. This excellent noise characteristic is attributed to a drastic reduction in the gate resistance by the T-shaped gate with a wide head and to the improved device performance.
Wideband 36- to 44-GHz MMIC Power Amplifier Using a 0.2-㎛ PHEMT Process
DongMinKang,JinHeeLee,HyungSupYoon,SungJinKim,JaeYeobShim,KyungHoLee 한국물리학회 2002 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.41 No.4
The design and fabrication of a Q-band 3-stage monolithic microwave integrated circuit (MMIC) amplifier for WLAN are presented using a 0.2-$\mu$m AlGaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor (PHEMT). In each stage of the MMIC, a negative feedback is used to achieve both a broadband and good stability. An input return loss under $-$4 dB, an output return loss under $-$10 dB, a gain of 14 dB, and a P1dB of 17 dBm at the Q-band (36$\sim$44 GHz) were measured. These results closely match the design results. The chip size is 2.8$\times$1.3 mm$^2$. This MMIC amplifier will be used as the unit cell to develop millimeter-wave transmitters for use in wideband wireless LAN systems.
Design and Implementation of 40-GHz-Band LNA MMICs with Super Low-Gain Flatness
Jin-HeeLee,Hyung-SupYoon,JaeYeobShim,Kyung-HoLee 한국물리학회 2002 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.40 No.4
This paper introduces the design and implementation of 40-GHz-band 4-stage/2-stage low-noise amplier with low-gain atness for wide-band wireless multimedia and satellite communication systems. The 40-GHz-band 4-stage MMIC demonstrate a small signal gain of more than 20 dB, an input return loss of 10.2 dB, and an output return loss of 21.8 dB for 4042 GHz. The gain atness of the 40-GHz-band 4-stage LNA was 0.1 dB for 4042 GHz. The noise gure of the 40 GHz-band 4-stage LNA was simulated to be less than 3.2 dB for 4042 GHz. While the 40-GHz-band 2-stage LNA MMIC demonstrate a small signal gain of more than 10.5 dB, an input return loss of 8.6 dB, and an output return loss of 19.8 dB for 4042 GHz. The gain atness of the 40-GHz-band 2-stage LNA was 0.4 dB for 4042 GHz. The noise gure of the 40-GHz-band 2-stage LNA was simulated to be less than 3.0 dB for 4042 GHz. The chip size of the 2-stage and the 4-stage LNA MMICs were 2.11.7 mm2 and 3.71.7 mm2, respectively.