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1.
This paper investigates the feasibility of using a lanthanum oxide thin film (La2O3) with a high dielectric constant as a gate dielectric on GaAs pHEMTs to reduce gate leakage current and improve the gate to drain breakdown voltage relative to the conventional GaAs pHEMT. An E/D mode pHEMT in a single chip was realized by selecting the appropriate La2O3 thickness. The thin La2O3 film was characterized: its chemical composition and crystalline structure were determined by X-ray photoelectron spectroscopy and X-ray diffraction, respectively. La2O3 exhibited good thermal stability after post-deposition annealing at 200, 400 and 600℃ because of its high binding-energy (835.6 eV). Experimental results clearly demonstrated that the La2O3 thin film was thermally stable. The DC and RF characteristics of Pt/La2O3/Ti/Au gate and conventional Pt/Ti/Au gate pHEMTs were examined. The measurements indicated that the transistor with the Pt/La2O3/Ti/Au gate had a higher breakdown voltage and lower gate leakage current. Accordingly, the La2O3 thin film is a potential high-k material for use as a gate dielectric to improve electrical performance and the thermal effect in high-power applications. 相似文献
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Chao-Hung Chen Hsien-Chin Chiu Chih-Wei Yang Jeffrey S. Fu Feng-Tso Chien 《Microelectronics Reliability》2012,52(1):147-150
In this study, a novel metal–semiconductor gate enhancement-mode (E-mode) and a metal–insulator-metal–semiconductor (MIMS) gate depletion-mode (D-mode) AlGaAs/InGaAs pseudomorphic high electron mobility transistor (pHEMT) on a single GaAs substrate have been developed by using high dielectric constant praseodymium insulator layer. The epitaxial layers were design for an enhancement-mode pHEMT after gate recess process. To achieve E/D-mode pHEMTs on single GaAs wafer, traditional Pt/Ti/Au metals were deposited as Schottky contact for E-mode pHEMTs and Pr/Pr2O3/Ti/Au were deposited as MIMS-gate for D-mode pHEMTs. This AlGaAs/InGaAs E-mode pHEMTs exhibit a gate turn-on voltage (VON) of +1 V and a gate-to-drain breakdown voltage of ?5.6 V, and these values were +7 V and ?34 V for MIMS-gate D-mode pHEMTs, respectively. Therefore, this high-k insulator in D-mode pHEMT is beneficial for suppressing the gate leakage current. Comparing to previous E/D-mode pHEMT technology, this E-mode pHEMTs and MIMS-gate D-mode pHEMTs exhibit a highly potential for high uniformity GaAs logic circuit applications due to its single recess process. 相似文献
3.
单片集成GaAs增强/耗尽型赝配高电子迁移率晶体管 总被引:1,自引:0,他引:1
介绍了单片集成GaAs增强/耗尽型赝配高电子迁移率晶体管(PHEMT)工艺。借助栅金属的热处理过程,形成了热稳定性良好的Pt/Ti/Pt/Au栅。AFM照片结果表明Pt金属膜表面非常平整,2nm厚度膜的粗糙度RMS仅为0.172nm。通过实验,我们还得出第一层Pt金属膜的厚度和退火后的下沉深度比大概为1:2。制作的增强型/耗尽型PHEMT的闽值电压(定义于1mA/mm)、最大跨导、最大饱和漏电流密度、电流增益截止频率分别是+0.185/-1.22V、381.2/317.5mS/mm、275/480mA/mm、38/34GHz。增强型器件在4英寸圆片上的阈值电压标准差为19mV。 相似文献
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采用脉冲激光沉积(PLD)法在Pt/Ti/SiO2/Si(001)基片上制备了Ba0.6Sr0.4TiO3(BST)薄膜,对Pt/BST/Pt电容器在空气中进行400℃快速退火(RTA)处理,研究了快速退火对Pt/BST/Pt电容器的结构和性能的影响。结果表明:快速退火虽然对BST薄膜的结晶质量影响较小,但却极大改善了Pt/BST/Pt电容器的电学性能。当测试频率为100kHz、直流偏压为0V时,介电损耗从快速退火前的0.07减小到0.03,介电常数和调谐率略有增加。快速退火后负向漏电流过大现象得到了明显抑制,正负向漏电流趋于对称,在300×103V/cm电场强度下,漏电流密度为4.83×10–5A/cm2。 相似文献
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The performance of InGaP-based pHEMTs as a function of gate metallization is examined for Mo/Au, Ti/Au, and Pt/Au gates. DC and microwave performance of pHEMT's with 0.7-μm gate lengths is evaluated. Transconductance, threshold voltage, ft, and fmax are found to depend strongly on gate metallization. High-speed performance is achieved, with ft of 41.3 GHz and f max of 101 GHz using Mo/Au gates. The difference in performance between devices with different gate metallizations is postulated to be due to a combination of the difference in Schottky barrier heights and different gate-to-channel spacings due to penetration of the gate metal into the InGaP barrier layer 相似文献
7.
Chou Y.C. Grundbacher R. Leung D. Lai R. Liu P.H. Kan Q. Biedenbender M. Wojtowicz M. Eng D. Oki A. 《Electron Device Letters, IEEE》2004,25(2):64-66
The Ti metal interdiffusion of Ti/Pt/Au gate metal stacks in 0.15-/spl mu/m GaAs PHEMTs subjected to high-temperature accelerated lifetest has been physically identified using scanning transmission electron microscopy. Further energy dispersive analysis with X-ray (EDX) analysis confirms the Ti diffusion into the AlGaAs Schottky barrier layer and the decrease of Schottky barrier height suggests the Ti-AlGaAs intermetallic formation, which is consistent with previous Rutherford backscattering spectroscopy/X-ray photoelectron spectroscopy studies. The Ti metal interdiffusion reduces the separation of the gate metal and InGaAs channel, thus leading to a slight Gm increase, positive shift in pinchoff voltage, and S21 increase during the preliminary portion of the lifetest. Accordingly, the Ti interdiffusion effect implies that the lifetime of GaAs PHEMTs subjected to high-temperature accelerated lifetest could be dependent upon the initial thickness of the Schottky layer underneath the gate metal. 相似文献
8.
A maximum clock frequency of 4.1 GHz was obtained for a GaAs digital integrated circuit using deep recess normally-on GaAs MESFETs with 1.2 ?m long gate and interdigitated Schottky diodes. The Ti/Pt/Au gate electrode was made by a lift-off technique with conventional photolithography. The minimum propagation delay of a NAND/AND gate was estimated to be 100 ps/gate for a fan-out of 2 from the self-oscillation frequency of the master-slave flip-flops. 相似文献
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The gate dielectrics of Ga2O3(As2O3) of the GaAs MOSFET were prepared by a low-cost and low-temperature liquid-phase chemically enhanced oxidation method. The temperature and oxide thickness dependence of gate dielectric films on GaAs MOSFET have been investigated. The leakage current and dielectric breakdown field were both studied. Both gate leakage current density and breakdown electrical field were found to depend on the oxide thickness and operating temperature. The increasing trend in gate leakage current and the decreasing trend in breakdown electrical field were observed upon reducing oxide thickness from 30 to 12 nm and increasing operating temperature from −50°C to 200°C. 相似文献
10.
The metallurgical stability of ohmic contacts: Pt, Pt/Ti, Au/Ti, Au/Pt/Ti, and Au/Pt/Ti/W, on a 500 Å thick p+-InGaAs base of InP/InGaAs/InP HBTs have been investigated as a function of anneal temperature. All contacts were stable after a 300°C-30 s anneal. Pt contact failed at 350°C whereas Pt/Ti, Au/Ti, and Au/Pt/Ti contacts failed at 400°C. The failure mechanism was a collector leakage short owing to the penetration of Pt or Ti through the thin base. Only HBTs with Au/Pt/Ti/W contact were still functional after a 400°C anneal with no apparent shift in the turn-on voltage for the emitter and collector junctions 相似文献
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《Electron Device Letters, IEEE》1984,5(7):241-243
Threshold voltage controls of Ni/Ti/Au gate and Ti/Au gate 2DEG AlGaAs/GaAs FET's through only heat treatment are investigated. Ni/Ti/Au gate FET's vary over quite a wide range from a depletion mode to an enhancement mode without degradation of FET characteristics after heat treatment at 300°C. The same experiment is made for Ti/Au gate FET's, but the threshold voltage change is negligibly small. It is confirmed that Ni/Ti/Au can be used as the gate metal for E-FET and Ti/Au as the gate metal for D-FET under simultaneous heat treatment. In addition, a mechanism for penetrating the barrier metal into the underlying layer is discussed. 相似文献
13.
Ti/Pt metal layers are an integral part of the gate stack of many GaAs PHEMTs and InP HEMTs. These devices are known to be affected by H 2 exposure. In this study, Auger Electron Spectroscopy (AES) measurements of Ti/Pt bilayers are correlated with electrical measurements of InP HEMTs fabricated with Ti/Pt/Au gates. The FET measurements show that H2 exposure shifts the device threshold voltage through the piezoelectric effect. AES reveals the formation of titanium hydride (TiHx) in Ti/Pt bilayers after identical H2 exposures. These results indicate that the volume expansion associated with TiHx formation causes compressive stress in Ti/Pt/Au gates, leading to the piezoelectric effect. After a subsequent recovery anneal in N2, the FET measurements show that VT recovers. AES measurements confirm that the TiHx in hydrogenated Ti/Pt bilayers also decreases after further annealing in N2 相似文献
14.
Can Zheng Coffie R. Buttari D. Champlain J. Mishra U.K. 《Electron Device Letters, IEEE》2002,23(7):380-382
In this letter, for the first time, an investigation of partially oxidized GaAs-on-insulator (GOI) AlGaAs/InGaAs/GaAs pseudomorphic HEMTs is reported. Fully oxidized pHEMTs demonstrated minimized substrate leakage current and high output impedance, but suffered from 30~40% charge loss. Fully oxidized devices also showed transconductance peaking that could be removed by controlled partial oxidation. Partially oxidized pHEMT devices showed improved power added efficiencies (PAEs) at a low supply voltage of 3.0 V compared to fully oxidized or unoxidized devices and negligible charge loss (<10%) 相似文献
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Low voltage organic thin film transistors(OTFTs) were created using polymethyl-methacrylate-co g-lyciclyl-methacrylate(PMMA-GMA) as the gate dielectric.The OTFTs performed acceptably at supply voltages of about 10 V.From a densely packed copolymer brush,a leakage current as low as 2×10~(-8) A/cm~2 was obtained.From the measured capacitance-insulator frequency characteristics,a dielectric constant in the range 3.9-5.0 was obtained. By controlling the thickness of the gate dielectric,the threshold voltage ... 相似文献
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Ming Shiahu Tsai Sun S.C. Tseung-Yuen Tseng 《Electron Devices, IEEE Transactions on》1999,46(9):1829-1838
The dielectric constant and the leakage current density of (Ba, Sr)TiO3 (BST) thin films deposited on various bottom electrode materials (Pt, Ir, IrO2/Ir, Ru, RuO2/Ru) before and after annealing in O2 ambient were investigated. The improvement of crystallinity of BST films deposited on various bottom electrodes was observed after the postannealing process. The dielectric constant and leakage current of the films mere also strongly dependent on the postannealing conditions. BST thin film deposited on Ir bottom electrode at 500°C, after 700°C annealing in O2 for 20 min, has the dielectric constant of 593, a loss tangent of 0.019 at 100 kHz, a leakage current density of 1.9×10 -8 A/cm2 at an electric field of 200 kV/cm with a delay time of 30 s, and a charge storage density of 53 fC/μm2 at an applied field of 100 kV/cm. The BST films deposited on Ir with post-annealing can obtain better dielectric properties than on other bottom electrodes in our experiments. And Ru electrode is unstable because the interdiffusion of Ru and Ti occurs at the interface between the BST and Ru after postannealing. The ten year lifetime of time-dependent dielectric breakdown (TDDB) studies indicate that BST on Pt, Ir, IrO2/Ir, Ru, and RuO2/Ru have long lifetimes over ten gears on operation at the voltage bias of 2 V 相似文献
18.
The thermal stability of ohmic contacts for AlGaAs/GaAs HBTs is presented. Ti/Pt/Au, Ti/Pt/Au and Cr/Pt/Au, and AuGe/Ni/Ti/Pt/Au were investigated for emitter, base, and collector contacts, respectively. As a result of 200 degrees C storage tests, it was found that these contacts did not limit the reliability of AlGaAs/GaAs HBTs.<> 相似文献
19.
Rohit Khanna L. Stafford S.J. Pearton T.J. Anderson F. Ren I.I. Kravchenko Amir Dabiran A. Osinsky Joon Yeob Lee Kwan-Young Lee Jihyun Kim 《Journal of Electronic Materials》2007,36(4):379-383
AlGaN/GaN High Electron Mobility Transistors (HEMTs) were fabricated with Ti/Al/TiB2/Ti/Au source/drain Ohmic contacts and a variety of gate metal schemes (Pt/Au, Ni/Au, Pt/TiB2/Au or Ni/TiB2/Au) and subjected to long-term annealing at 350°C. By comparison with companion devices with conventional Ti/Al/Pt/Au Ohmic
contacts and Pt/Au gate contacts, the HEMTs with boride-based Ohmic metal and either Pt/Au, Ni/Au or Ni/TiB2/Au gate metal showed superior stability of both source-drain current and transconductance after 25 days aging at 350°C. 相似文献