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센서 및 통신 응용 핵심 소재 In<sub>0.8</sub>Ga<sub>0.2</sub>As HEMT 소자의 게이트 길이 스케일링 및 주파수 특성 개선 연구
조현빈 ( Hyeon-bhin Jo ),김대현 ( Dae-hyun Kim ) 한국센서학회 2021 센서학회지 Vol.30 No.6
The impact of the gate length (L<sub>g</sub>) on the DC and high-frequency characteristics of indium-rich In<sub>0.8</sub>Ga<sub>0.2</sub>As channel high-electron mobility transistors (HEMTs) on a 3-inch InP substrate was inverstigated. HEMTs with a source-to-drain spacing (L<sub>SD</sub>) of 0.8 μm with different values of L<sub>g</sub> ranging from 1 μm to 19 nm were fabricated, and their DC and RF responses were measured and analyzed in detail. In addition, a T-shaped gate with a gate stem height as high as 200 nm was utilized to minimize the parasitic gate capacitance during device fabrication. The threshold voltage (V<sub>T</sub>) roll-off behavior against L<sub>g</sub> was observed clearly, and the maximum transconductance (g<sub>m_max</sub>) improved as L<sub>g</sub> scaled down to 19 nm. In particular, the device with an L<sub>g</sub> of 19 nm with an L<sub>SD</sub> of 0.8 mm exhibited an excellent combination of DC and RF characteristics, such as a g<sub>m_max</sub> of 2.5 mS/μm, On resistance (R<sub>ON</sub>) of 261 Ω·μm, current-gain cutoff frequency (f<sub>T</sub>) of 738 GHz, and maximum oscillation frequency (f<sub>max</sub>) of 492 GHz. The results indicate that the reduction of L<sub>g</sub> to 19 nm improves the DC and RF characteristics of InGaAs HEMTs, and a possible increase in the parasitic capacitance component, associated with T-shap, remains negligible in the device architecture.
Yun, Do-Young,Jo, Hyeon-Bhin,Son, Seung-Woo,Baek, Ji-Min,Lee, Jung-Hee,Kim, Tae-Woo,Kim, Dae-Hyun,Tsutsumi, Takuya,Sugiyama, Hiroki,Matsuzaki, Hideaki IEEE 2018 IEEE electron device letters Vol.39 No.12
<P>In this letter, we investigated the impact of the source-to-drain spacing ( <TEX>${L}_{\textsf {SD}}$</TEX>) on the dc and high-frequency characteristics of indium-rich In<SUB>0.8</SUB>Ga<SUB>0.2</SUB>As/In<SUB>0.52</SUB>Al<SUB>0.48</SUB>As high-electron mobility transistors (HEMTs) on a 3-in InP substrate. <TEX>${L}_{g} = \textsf {87}$</TEX> nm HEMTs with different values of <TEX>${L}_{\textsf {SD}}$</TEX> were fabricated ranging from 1.55 to <TEX>$0.8~\mu \text{m}$</TEX>, and their dc and RF responses were measured and analyzed in detail. In order to suppress the increase of the parasitic gate capacitance, we maintained the gate stem height as high as 200 nm in our device fabrication. Both the maximum transconductance (g<SUB>m_max</SUB>) and on-resistance ( <TEX>${R}_{\textsf {ON}}$</TEX>) improved as <TEX>${L}_{\textsf {SD}}$</TEX> scaled down to <TEX>$0.8~\mu \text{m}$</TEX>. At the same time, the high-frequency figures of the merit, such as current-gain cutoff frequency ( <TEX>${f}_{T}$</TEX>) and maximum oscillation frequency ( <TEX>${f}_{\textsf {max}}$</TEX>), increased with the reduction of <TEX>${L}_{\textsf {SD}}$</TEX>. These improvements are attributed to the reduction of series resistances. In particular, the <TEX>${L}_{g} =87$</TEX> nm device with an <TEX>${L}_{\textsf {SD}} = \textsf {0.8} \mu \text{m}$</TEX> exhibited an excellent combination of dc and RF characteristics, such as g<SUB>m_max</SUB> = 2.7 mS/ <TEX>$\mu \text{m}$</TEX>, <TEX>${R}_{\textsf {ON}} = \textsf {318}\,\,\Omega \cdot \mu \text{m}$</TEX>, <TEX>${f}_{T} = \textsf {519}$</TEX> GHz, and <TEX>${f}_{\textsf {max}} = \textsf {645}$</TEX> GHz, respectively. The results obtained in this letter indicate that the reduction of <TEX>${L}_{\textsf {SD}}$</TEX> down to <TEX>$0.8~\mu \text{m}$</TEX> continues to improve both the dc and RF characteristics of the InGaAs/InAlAs HEMTs, and a possible increase in parasitic capacitance components, associated with a T-shaped, is still negligible in our device architecture.</P>
Rho, Tae-Beom,Jo, Hyeon-Bhin,Kim, Tae-Woo,Kim, Dae-Hyun Elsevier 2019 Solid-state electronics Vol.162 No.-
<P><B>Abstract</B></P> <P>In this letter, we propose a unified method to extract the effective mobility (<I>μ<SUB>eff</SUB> </I>) of In<SUB>0.52</SUB>Al<SUB>0.48</SUB>As/In<SUB>0.7</SUB>Ga<SUB>0.3</SUB>As/In<SUB>0.52</SUB>Al<SUB>0.48</SUB>As single-quantum-well (SQW) metal-insulator-semiconductor field-effect-transistors (MISFETs). The proposed method relies only on the measured high-frequency scattering-parameters (S-parameters) of the MISFETs in the linear regime. Two key metrics of MOS devices, intrinsic output conductance (g<SUB>o_i</SUB>) and intrinsic gate capacitance (C<SUB>g_i</SUB>), were extracted directly from the measured S-parameters using two-port network parameter theories, allowing us to compute the effective mobility of the MOS devices. Since the method only requires the small-signal S-parameter measurement data, it would be applicable to any kind of FETs and could be fruitful for studying the dependence of the effective mobility on lateral electric field intensity.</P>
Lee In-Geun,Ko Dae-Hong,Yun Seung-Won,Kim Jun-Gyu,Jo Hyeon-Bhin,Kim Dae-Hyun,Tsutsumi Takuya,Sugiyama Hiroki,Matsuzaki Hideaki 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.78 No.6
Herein we describe theoretical and experimental analysis of the source resistance (Rs) components in In0.7Ga0.3As/ In0.52Al0.48As quantum-well (QW) high-electron-mobility transistors (HEMTs) on an InP substrate. First, we analytically modeled Rs using a three-layer formula, separately modeling the regions of the ohmic contact, the gate-to-source access, and the side-recessed regions. The resistances of the ohmic contact and access regions were analyzed in a distributed-network manner with two different transfer lengths, whereas the resistance associated with the side-recess region near the gate edge was modeled by using a lumped element. To verify the accuracy of the proposed Rs model, we fabricated two different types of transmission-line-method (TLM) test patterns as well as long-channel In0.7Ga0.3As/ In0.52Al0.48As QW HEMTs, and compared their measured and modeled Rs. The modeled Rs was in excellent agreement with the measured Rs from the recessed TLM patterns and the long-channel HEMTs. Since the widths of the ohmic contact to the heavily doped In0.53Ga0.47As capping layer and the gate-to-source access region were typically much greater than corresponding transfer lengths ( L T_cap and L T_barrier ), those distributed networks could be simplified to a lumped-element based one-layer model, revealing that the tunneling resistance ( R barrier ) through the In0.52Al0.48As barrier should be carefully considered to minimize the Rs of InxGa1− xAs QW HEMTs together with S/D contact resistances and LGS.