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Evaluation of an InAs HEMT with source-connected field plate for high-speed and low-power logic applications
(2019-07-01)
Yao, Jing Neng
;
Lin, Yueh Chin
;
Lin, Min Song
;
Huang, Ting Jui
;
Hsu, Heng Tung
In this study, we have presented a source-connected field plate (SCFP) InAs high electron mobility transistor (HEMT) and evaluated its potential for using in high-speed and low-power logic applications. The fabricated device demonstrated good electrical characteristics including low subthreshold swing (SS) of 76 mV/decade, drain induced barrier lowering (DIBL) of 44 mV/V, I-ON/I-OFF ratio of 2.4x10(4), an off-state gate leakage current of less than 5x10(-6) A/mm and a G(m,max) of 1100 mS/mm at V-DS = 0.5 V. When increasing the drain-source bias (V-DS) to 1.0 V, the G(m,max) increased to 1750 mS/mm with a cut-off frequency of 113 GHz. These results revealed that the fabrication of source-connected field plate InAs HEMTs achieved excellent device performance for high-speed and low-power logic applications.
Evaluation of a 100-nm Gate Length E-Mode InAs High Electron Mobility Transistor With Ti/Pt/Au Ohmic Contacts and Mesa Sidewall Channel Etch for High-Speed and Low-Power Logic Applications
(2018-01-01)
Yao, Jing-Neng
;
Lin, Yueh-Chin
;
Hsu, Heng-Tung
;
Yang, Kai-Chun
;
Hsu, Hisang-Hua
In this paper, a 100-nm gate length InAs high electron mobility transistor (HEMT) with non-alloyed Ti/Pt/Au ohmic contacts and mesa sidewall channel etch was investigated for high-speed and low-power logic applications. The device exhibited a low subthreshold swing (SS) of 63.3 mV/decade, a drain induced barrier lowering value of 23.3 mV/V, an I-on/I-off ratio of 1.34 x 10(4), a G(m,max)/SS ratio of 27.6, a current gain cut-off frequency of 439 GHz with a gate delay time of 0.36 ps, and an off-state gate leakage current of less than 1.6 x 10(-5) A/mm at V-DS = 0.5 V. These results demonstrated that the presence of non-annealed ohmic contacts with mesa sidewall etch process allowed the fabrication of InAs HEMTs with excellent electrical characteristics for high-speed and low-power logic applications.
Study of the inversion behaviors of Al2O3/InxGa1-xAs metal-oxide-semiconductor capacitors with different In contents
(2010-01-01)
Wu, Yun-Chi
;
Chang, Edward Yi
;
Lin, Yueh-Chin
;
Kei, Chi-Chung
;
Hudait, Mantu K.
InxGa1-xAs III-V compound semiconductor metal-oxide-semiconductor field-effect transistors have become a popular topic recently due to the higher drift velocity, and lower effective mass of the InxGa1-xAs materials. The impact of In content on the accumulation and inversion behaviors of the Al2O3/InxGa1-xAs capacitors is investigated in this study. For the various InxGa1-xAs materials studied, the Al2O3/InAs MOS system showed the strongest inversion phenomena due to the shorter response time of minority carrier of InAs compared to other InxGa1-xAs materials. Also, very low gate leakage current in the 10(-8) A/cm(2) range was observed for these capacitors. These results demonstrate that Al2O3/InAs MOS system with strong inversion phenomena and low leakage gate current is potential candidate for future high-performance low power logic MOSFET applications. (C) 2009 Elsevier Ltd. All rights reserved.
Electrical Characterization of Al2O3/n-InAs Metal-Oxide-Semiconductor Capacitors With Various Surface Treatments
(2011-06-01)
Trinh, H. D.
;
Brammertz, G.
;
Chang, E. Y.
;
Kuo, C. I.
;
Lu, C. Y.
Ex situ sulfide and HCl wet chemical treatments in conjunction with in situ trimethyl aluminum (TMA) pretreatment were performed before the deposition of Al2O3 on n-InAs surfaces. X-ray photoelectron spectroscopy analyses show a significant reduction of InAs native oxides after different treatments. The capacitance-voltage C-V characterization of Al2O3/n-InAs structures shows that the frequency dispersion in the accumulation regime is small (< 0.75%/dec) and does not seem to be significantly affected by the different surface treatments, whereas the latter improves depletion and inversion behaviors of the n-channel metal-oxide-semiconductor capacitors. The interface trap density profiles extracted from the simulation mainly show donorlike interface states inside the InAs band gap and in the lower part of the conduction band. The donorlike traps inside the InAs band gap and in the lower part of the conduction band were significantly reduced by using wet-chemical-plus-TMA treatments, in agreement with C-V characteristics.
RF Performance Improvement of Metamorphic High-Electron Mobility Transistor Using (InxGa1-xAs)(m)/(InAs)(n) Superlattice-Channel Structure for Millimeter-Wave Applications
(2010-07-01)
Kuo, Chien-I
;
Hsu, Heng-Tung
;
Chen, Yu-Lin
;
Wu, Chien-Ying
;
Chang, Edward Yi
High-performance metamorphic high-electron mobility transistors (MHEMTs) using an (InxGa1-xAs)(m)/(InAs)(n) superlattice structure as a channel layer have been fabricated successfully. These HEMTs with 80-nm gate length exhibited a high drain current density of 392 mA/mm and a transconductance of 991 mS/mm at 1.2-V drain bias. Compared with a regular InxGa1-xAs channel, the superlattice-channel HEMTs showed an outstanding performance due to the high electron mobility and better carrier confinement in the (InxGa1-xAs)(m)/(InAs)(n) channel layer. When biased at 1.2 V, the current gain cutoff frequency (f(T)) and the maximum oscillation frequency (f(max)) were extracted to be 304 and 162 GHz, respectively. As for noise performance, the device demonstrated a 0.75-dB minimum noise figure(NFmin) with an associated gain of 9.6 dB at 16 GHz. Such superior performance has made the devices with a superlattice channel well suitable for millimeter-wave applications.
Anisotropic nature of hole g-factor in individual InAs quantum rings
(2017-02-01)
Kaji, R.
;
Tominaga, T.
;
Wu, Y. -N.
;
Wu, M. -F.
;
Cheng, S. -J.
The in-plane g-factors of electron and hole spins (g perpendicular to e, g perpendicular to h) confined in the individual InAs/GaAs quantum rings (QRs) were investigated by using experimental and theoretical approaches. From the measurements, we found that the experimentally obtained \g perpendicular to h\varies largely from QR to QR, while the variation in \g perpendicular to e\ is small. In addition, the in-plane (x-y) and the out-of-plane (x-z) anisotropies in hole g-factor were obviously confirmed while the electron g-factor exhibits isotropic natures in both cases. From the model calculations, the effects of the shape anisotropies and the uniaxial stress were examined. The shape anisotropy in QRs modifies the spatial distributions of hole wavefunctions. Thus, it brings the resultant changes in the degree of valence-band mixing and \g perpendicular to h\, and combined with uniaxial stress, a larger modulation in \g perpendicular to h\ was achieved. Although more detailed discussions are necessary at this stage, our findings will give valuable information for the g-factor control in semiconductor nanostructures.
Hole g-Factor Anisotropies in Individual InAs Quantum Rings
(2016)
Kaji, R.
;
Tominaga, T.
;
Wu, Y. -N.
;
Wu, M. -F.
;
Cheng, S. -J.
We investigated the electron and hole g-factors in individual InAs/GaAs quantum rings (QRs). From the magneto-photoluminescence measurements under a transverse magnetic field, we evaluated the in-plane g-factors of electron and hole spins by rotating the sample systematically around the crystal growth axis. The experimental results indicate that the in-plane and the out-of-plane anisotropies in hole g-factor are larger than those of electron g-factor, and the value of the hole in-plane g-factor varies largely from QR to QR while the electron g-factor is almost a constant value. From the model calculation considering the effects of shape anisotropies and uniaxial stress, we examined the correlation between the in-plane g-factors and the degree of valence band mixing. Further, the experimentally obtained trend in g-factors was in agreement qualitatively with theoretical consideration.
Pressure-Induced Phase Transitions in InAs Studied by Angular-Dispersive X-ray Diffraction and Raman Spectroscopy
(2015-06-01)
Lin, Chih-Ming
;
Lin, Kung-Liang
;
Chern, Yu-Ker
;
Lin, Yu-Kun
;
Chuang, Yu-Chun
Pressure-induced phase transitions in indium arsenide (In As) at ambient temperature were investigated by using angular-dispersive X-ray diffraction (ADXRD) and Raman scattering under high pressure up to around 9.8(1) and 9.9(2) GPa, respectively, with a 4:1 (in volume ratio) methanol-ethanol mixture as the pressure transmitting medium (PTM). In situ ADXRD measurements revealed that In As starts to transform from zinc blende (ZB) structure to rock-salt (RS) phase at 6.7(1) GPa, consistent with most previously reported studies. The phase transition proceeds steadily over a wide range of pressures and reaches completion at the highest applied pressure of 9.8 GPa with significant metallization, as suggested by the disappearance of Raman modes. In contrast to previous studies, our data did not show evidence of structural transition to Cnncm phase, presumably due to the different PTMs used and/or insufficient pressure applied. The order of appearance of the major diffraction peaks of RS phase In As with increasing pressure and intensity are explained by the binding energy density of the corresponding plane families. The zero-pressure isothermal bulk moduli (B-0) and its first-pressure derivatives (B-0\') for the ZB In As are 64(4) GPa and 3.8(2), respectively. The intensity of both the LO and TO phonon modes of ZB phase In As exhibits an abrupt decrease at 7.7(1) GPa, where equal weight fractions of ZB and RS phases are identified, suggesting the metallic nature of the RS phase.
Efficiency of quantum dot solar cell enhanced by improving quantum dots performance
(2015-02-01)
Weng, H. L.
;
Ueng, H. Y.
;
Lee, C. P.
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
We propose an innovative description to provide a quantitative basis to enhance the conversion efficiency of InAs/GaAs quantum dot solar cells (QDSC). A theoretical approach and numerical simulation are used to improve the performance of the quantum dots and analyze the relevance to enhance the conversion efficiency. The absorption coefficient of QDs is determined in terms of dot material, dot size, size dispersion, and shape, which are used to obtain a better match between the absorption spectrum of QDs with the portion of the solar spectrum. Either increasing the surface density for raising the photocurrent or enlarging the dot size for matching well the solar spectrum is a trade-off issue. The influence of surface density, spacer thickness, and number of dot layers on the open-circuit voltage and efficiency is discussed in detail. Moreover, volume fraction can be taken as a balance reference for the counteracting effect between J(SC) and V-OC.
電流截止頻率大於500GHz之砷化銦通道高電子遷移率電晶體其製作與高速邏輯應用之評估
(2008)
張翼
;
CHANG EDWARD YI
;
國立交通大學材料科學與工程學系(所)
過去四十年元件線寬的微縮一直是Si 半導體提升元件特性最直接也最有效的方法，但是最近幾年碰到了幾個難以克服的問題。而這些問題難以解決的原因在於矽半導體本身材料特性的限制。因此導入新的高載子遷移率材料，如砷化鎵等三五族半導體，被視為下一個世代提升元件特性最有效的方法之一。矽電晶體之物理閘極線寬目前為90 奈米，下一階段約為50 奈米世代，預計於2011 年，電晶體的尺度約為10 奈米，已經接近半導體製程上的物理極限。在此線寬下使用具有較高電子遷移率特性的三五族材料被視為延伸莫爾定律的解決方案之一。本計畫的主要目的是製作電流截止頻率(fT)高於500GHz 的電晶體，將使用閘極線寬為40 奈米與超高電子遷移率的砷化銦(InAs)為通道材料。評估其操作在超高頻率時，應用於超低消耗功率、高速邏輯電晶體之可行性。砷化銦材料的優點在於電子在此材料內移動時有極高的電子遷移率，而且在較低電壓時就可以獲得相當大的驅動電流。因此只要使用砷化銦為通道層材料，就可以有效提高電子遷移率以及電子浮移速度，使得元件操作更快速更高頻而且具有更好的特性。此外還可以使元件在較低電壓下操作，將可以大幅降低電晶體的消耗功率，達到超低電壓、超低功率的操作需求。此外，將配合本實驗室砷化鎵完整的製程線，可製作出操作在超高頻率、超低電壓之數位邏輯積體電路。

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