P. D. Ye

Purdue University, ウェストラファイエット, Indiana, United States

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Publications (229)602.67 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The interfacial chemistry between the “half cycle” atomic layer deposited (ALD) Al2O3 and black phosphorus (black-P) was examined using in situ X-ray photoelectron spectroscopy (XPS). Two samples, native and freshly exfoliated, are investigated to understand the effect of oxidation on the initial ALD nucleation. It is found that annealing samples in the ALD chamber results in an increase of oxidation, caused most likely by oxygen transferring from surface adventitious contamination. After the half cycle ALD process, the P-oxide concentration increases, indicating interface deterioration during the Al2O3 deposition. Based on the Al2O3 nucleation or growth behavior observed in the half cycle ALD studies, a true ALD growth tends to occur only after formation of a complete monolayer of oxide on the clean black-P surface with minimum oxidation concentration.
    Microelectronic Engineering 11/2015; 147. DOI:10.1016/j.mee.2015.04.014 · 1.34 Impact Factor
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    ABSTRACT: High-performance 0.1- $mu text{m}$ InAlN/GaN high electron-mobility transistors (HEMTs) have been successfully developed for power amplifiers operating at E-band (targeting 71–76 and 81–86-GHz bands). High maximum drain current of 1.75 A/mm and maximum extrinsic transconductance of 0.8 S/mm have been achieved for depletion-mode devices. Enhancement-mode HEMTs have also shown maximum drain current of 1.5 A/mm and maximum extrinsic transconductance of 1 S/mm. The selection of atomic layer deposition aluminum oxide (Al2O3) for device passivation enables a two-terminal breakdown voltage of $sim 25$ V, excellent subthreshold characteristics as well as the pulsed-IV featuring little current collapse for both types of HEMTs. When biased at a drain voltage of 10 V, a first-pass two-stage power amplifier design based on 0.1- $mu text{m}$ depletion-mode devices has demonstrated an output power of 1.43 W with 12.7% power-added efficiency at 86 GHz, a level of performance that has been attained previously only by state-of-the-art counterparts based on AlGaN/GaN HEMTs at a much higher drain bias and compression level.
    IEEE Electron Device Letters 05/2015; 36(5):442-444. DOI:10.1109/LED.2015.2409264 · 3.02 Impact Factor
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    ABSTRACT: A novel recessed channel and source/drain (S/D) technique is employed in Ge nMOSFETs, which greatly improves metal contacts to n-type Ge with contact resistance of down to 0.23 $Omega cdot {rm mm}$ and enhances gate electrostatic control with $I_{rm ON} / I_{rm OFF}$ of $> 10^{5}$ . The recessed S/D contacts are thoroughly investigated, showing strong dependence on the doping profile. For the first time, the drain current of Ge nMOSFETs has exceeded 1 A/mm with an $I_{d}$ of 1043 mA/mm on a 40-nm $L_{rm ch}$ device. Scalability study is carried out in deep sub-100-nm region on Ge nMOSFETs with $L_{rm ch}$ down to 25 nm. Interface study is also conducted with a new postoxidation method introduced, which significantly reduces the interface trap density. Device behaviors corresponding to interface traps are also investigated through a Technology Computer Aided Design simulation.
    IEEE Transactions on Electron Devices 05/2015; 62(5):1419-1426. DOI:10.1109/TED.2015.2412878 · 2.36 Impact Factor
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    ABSTRACT: The metal contacts on 2D black phosphorus field-effect transistor and photodetectors are studied. The metal work functions can significantly impact the Schottky barrier at the metal-semiconductor contact in black phosphorus devices. Higher metal work functions lead to larger output hole currents in p-type transistors, while ambipolar characteristics can be observed with lower work function metals. Photodetectors with record high photoresponsivity (223 mA/W) are demonstrated on black phosphorus through contact-engineering.
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    ABSTRACT: Black phosphorus has been revisited recently as a new two-dimensional material showing potential applications in electronics and optoelectronics. Here we report, for the first time, the anisotropic in-plane thermal conductivity of suspended few-layer black phosphorus measured by micro-Raman spectroscopy. The armchair and zigzag thermal conductivities ($k_{armchair}$ and $k_{zigzag}$) are ~20 W/mK and ~40 W/mK for black phosphorus films thicker than 15 nm, respectively, and decrease to ~10 W/mK and ~20 W/mK as the film thickness is reduced, exhibiting significant anisotropy of in-plane thermal transport and strong surface scattering of acoustic phonons. The thermal conductivity anisotropic ratio $k_{zigzag}/k_{armchair}$ is found to be ~2 for thick black phosphorus films and drops to ~1.5 for the thinnest 9.5-nm-thick film. First-principles modeling of few-layer black phosphorus reveals that the observed anisotropy is primarily related to the asymmetric phonon dispersion, whereas the intrinsic phonon scattering rates are found to be similar along the armchair and zigzag directions. Surface scattering in the black phosphorus films is shown to strongly suppress the contribution of long-mean-free-path acoustic phonons.
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    ABSTRACT: Inversion-mode GaAs wave-shaped metal-oxide-semiconductor field-effect transistors (WaveFETs) are demonstrated using atomic-layer epitaxy of La2O3 as gate dielectric on (111)A nano-facets formed on a GaAs (100) substrate. The wave-shaped nano-facets, which are desirable for the device on-state and off-state performance, are realized by lithographic patterning and anisotropic wet etching with optimized geometry. A well-behaved 1 μm gate length GaAs WaveFET shows a maximum drain current of 64 mA/mm, a subthreshold swing of 135 mV/dec, and an ION/IOFF ratio of greater than 107.
    Applied Physics Letters 02/2015; 106(7):073506. DOI:10.1063/1.4913431 · 3.52 Impact Factor
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    ABSTRACT: We demonstrate a single-step, laser-based technique to fabricate silicon nanowire field effect transistors. Boron-doped silicon nanowires are synthesized using a laser-direct-write chemical vapor deposition process, which can produce nanowires as small as 60 nm, far below the diffraction limit of the laser wavelength of 395 nm. In addition, the method has the advantages of in situ doping, catalyst-free growth, and precise control of nanowire position, orientation, and length. Silicon nanowires are directly fabricated on an insulating surface and ready for subsequent device fabrication without the need for transfer and alignment, thus greatly simplifying device fabrication processes. Schottky barrier nanowire field effect transistors with a back-gate configuration are fabricated from the laser-direct-written Si nanowires and electrically characterized.
    Nanotechnology 02/2015; 26(5):055306. DOI:10.1088/0957-4484/26/5/055306 · 3.67 Impact Factor
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    ABSTRACT: High performance-scaled MoS2 transistors down to 100 nm are studied at various temperatures down to 20 K, where highest drive current of 800 μA μm(-1) can be achieved. Extremely low electrical noise of 2.8 × 10(-10) μm(2) Hz(-1) at 10 Hz is also achieved at room temperature. Furthermore, negative differential resistance behavior is experimentally observed and its origin of self-heating is identified using pulsed-current-voltage measurements. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Advanced Materials 01/2015; 27(9). DOI:10.1002/adma.201405068 · 15.41 Impact Factor
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    ABSTRACT: Layered two-dimensional (2D) semiconducting transition metal dichalcogenides (TMD) have been widely isolated, synthesized, and characterized recently. Numerous 2D materials are identified as the potential candidates as channel materials for future thin film technology due to their high mobility and the exhibiting bandgaps. While many TMD filed-effect transistors (FETs) have been widely demonstrated along with a significant progress to clearly understand the device physics, large contact resistance at metal/semiconductor interface still remain a challenge. From 2D device research point of view, how to minimize the Schottky barrier effects on contacts thus reduce the contact resistance of metals on 2D materials is very critical for the further development of the field. Here, we present a review of contact research on molybdenum disulfide and other TMD FETs from the fundamental understanding of metal-semiconductor interfaces on 2D materials. A clear contact research strategy on 2D semiconducting materials is developed for future high-performance 2D FETs with aggressively scaled dimensions.
    10/2014; 2(9). DOI:10.1063/1.4894198
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    Han Liu, Yuchen Du, Yexin Deng, Peide D. Ye
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    ABSTRACT: Phosphorus is one of the most abundant elements preserved in earth, and it comprises a fraction of 0.1% of the earth crust. In general, phosphorus has several allotropes, and the two most commonly seen allotropes, i.e. white and red phosphorus, are widely used in explosives and safety matches. In addition, black phosphorus, though rarely mentioned, is a layered semiconductor and has great potential in optical and electronic applications. Remarkably, this layered material can be reduced to one single atomic layer in the vertical direction owing to the van der Waals structure, and is known as phosphorene, in which the physical properties can be tremendously different from its bulk counterpart. In this review article, we trace back to the research history on black phosphorus of over 100 years from the synthesis to material properties, and extend the topic from black phosphorus to phosphorene. The physical and transport properties are highlighted for further applications in electronic and optoelectronics devices.
    Chemical Society Reviews 10/2014; 44(9). DOI:10.1039/C4CS00257A · 30.43 Impact Factor
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    ABSTRACT: Low-resistivity metal-semiconductor (M-S) contact is one of the urgent challenges in the research of 2D transition metal dichalcogenides (TMDs). Here, we report a chloride molecular doping technique which greatly reduces the contact resistance (Rc) in the few-layer WS2 and MoS2. After doping, the Rc of WS2 and MoS2 have been decreased to 0.7 kohm*um and 0.5 kohm*um, respectively. The significant reduction of the Rc is attributed to the achieved high electron doping density thus significant reduction of Schottky barrier width. As a proof-ofconcept, high-performance few-layer WS2 field-effect transistors (FETs) are demonstrated, exhibiting a high drain current of 380 uA/um, an on/off ratio of 4*106, and a peak field-effect mobility of 60 cm2/V*s. This doping technique provides a highly viable route to diminish the Rc in TMDs, paving the way for high-performance 2D nano-electronic devices.
    Nano Letters 10/2014; 14(11). DOI:10.1021/nl502603d · 12.94 Impact Factor
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    ABSTRACT: This letter evaluates temporal and thermal stability of a state-of-the-art few-layer phosphorene MOSFET with Al2O3 surface passivation and Ti/Au top gate. As fabricated, the phosphorene MOSFET was stable in atmosphere for at least 100 h. With annealing at 200{\deg}C in dry nitrogen for 1 h, its drain current increased by an order of magnitude to approximately 100 mA/mm, which could be attributed to the reduction of trapped charge in Al2O3 and/or Schottky barrier at the source and drain contacts. Thereafter, the drain current was stable between -50{\deg}C and 150{\deg}C up to at least 1000 h. These promising results suggest that environmental protection of phosphorene should not be a major concern, and passivation of phosphorene should focus on its effect on electronic control and transport as in conventional silicon MOSFETs. With cutoff frequencies approaching the gigahertz range, the present phosphorene MOSFET, although far from being optimized, can meet the frequency and stability requirements of most flexible electronics for which phosphorene is intrinsically advantageous due to its corrugated lattice structure.
    IEEE Electron Device Letters 10/2014; 35(12). DOI:10.1109/LED.2014.2362841 · 3.02 Impact Factor
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    Yuchen Du, Han Liu, Yexin Deng, Peide D. Ye
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    ABSTRACT: Although monolayer black phosphorus (BP) or phosphorene has been successfully exfoliated and its optical properties have been explored, most of electrical performance of the devices is demonstrated on few-layer phosphorene and ultra-thin BP films. In this paper, we study the channel length scaling of ultra-thin BP field-effect transistors (FETs), and discuss a scheme for using various contact metals to change transistor characteristics. Through studying transistor behaviors with various channel lengths, the contact resistance can be extracted from the transfer length method (TLM). With different contact metals, we find out that the metal/BP interface has different Schottky barrier heights, leading to a significant difference in contact resistance, which is quite different from previous studies of transition metal dichalcogenides (TMDs) such as MoS2 where Fermi-level is strongly pinned near conduction band edge at metal/MoS2 interface. The nature of BP transistors are Schottky barrier FETs, where the on and off states are controlled by tuning the Schottky barriers at the two contacts. We also observe the ambipolar characteristics of BP transistors with enhanced n-type drain current and demonstrate that the p-type carriers can be easily shifted to n-type or vice versus by controlling the gate bias and drain bias, showing the potential to realize BP CMOS logic circuits.
    ACS Nano 08/2014; 8(10). DOI:10.1021/nn502553m · 12.03 Impact Factor
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    Adam T. Neal, Yuchen Du, Han Liu, Peide D. Ye
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    ABSTRACT: We have determined the spin-orbit scattering length of two-dimensional layered 2H-TaSe2 metallic crystals by detailed characterization of the weak anti-localization phenomena in this strong spin-orbit interaction material. By fitting the observed magneto-conductivity, the spin-orbit scattering length for 2H-TaSe2 is determined to be 17 nm in the few-layer films. This small spin-orbit scattering length is comparable to that of Pt, which is widely used to study the spin Hall effect, and indicates the potential of TaSe2 for use in spin Hall effect devices. In addition to strong spin-orbit coupling, a material must also support large charge currents to achieve spin-transfer-torque via the spin Hall effect. Therefore, we have characterized the room temperature breakdown current density of TaSe2 in air, where the best breakdown current density reaches 3.7$\times$10$^7$ A/cm$^2$. This large breakdown current further indicates the potential of TaSe2 for use in spin-torque devices and two-dimensional device interconnect applications.
    ACS Nano 08/2014; 8(9). DOI:10.1021/nn5027164 · 12.03 Impact Factor
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    ABSTRACT: Phosphorene, an elemental 2D material, which is the monolayer of black phosphorus, has been mechanically exfoliated recently. In its bulk form, black phosphorus shows high carrier mobility (~10000 cm2/V•s) and a ~0.3 eV direct bandgap. Well-behaved p-type field-effect transistors with mobilities of up to 1000 cm2/V•s, as well as phototransistors, have been demonstrated on few-layer black phosphorus, showing its promise for electronics and optoelectronics applications due to its high mobility and thickness-dependence direct bandgap. However, p-n junctions, the basic building blocks of modern electronic and optoelectronic devices, have not yet been realized based on black phosphorus. In this letter, we demonstrate a gate tunable p-n diode based on a p-type black phosphorus/n-type monolayer MoS2 van der Waals p-n heterojunction. Upon illumination, these ultra-thin p-n diodes show a maximum photodetection responsivity of 418 mA/W at the wavelength of 633 nm, and photovoltaic energy conversion with an external quantum efficiency of 0.3%. These p-n diodes show promise for broadband photodetection and solar energy harvesting.
    ACS Nano 07/2014; 8(8). DOI:10.1021/nn5027388 · 12.03 Impact Factor
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    ABSTRACT: In this paper, we report a novel chemical doping technique to reduce the contact resistance (Rc) of transition metal dichalcogenides (TMDs) - eliminating two major roadblocks (namely, doping and high Rc) towards demonstration of high-performance TMDs field-effect transistors (FETs). By using 1,2 dichloroethane (DCE) as the doping reagent, we demonstrate an active n-type doping density > 2*1019 cm-3 in a few-layer MoS2 film. This enabled us to reduce the Rc value to a record low number of 0.5 kohm*um, which is ~10x lower than the control sample without doping. The corresponding specific contact resistivity (pc) is found to decrease by two orders of magnitude. With such low Rc, we demonstrate 100 nm channel length (Lch) MoS2 FET with a drain current (Ids) of 460 uA/um at Vds = 1.6 V, which is twice the best value reported so far on MoS2 FETs.
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    ABSTRACT: InAs gate-all-around (GAA) nanowire MOSFETs are experimentally demonstrated for the first time by a top-down approach [1-3]. Thanks to the well-controlled nanowire release process and the novel ALD high-k/metal gate stack process, InAs nFETs with channel length (Lch) ranging from 380 to 20 nm and nanowire width (WNW) from 60 to 20 nm are achieved. With an EOT of 3.9 nm, high drain current of 4.3 A/mm at Vds = Vgs = 2 V and maximum transconductance (gmax) of 1.6 S/mm at Vds = 1 V are obtained in a device with WNW = 20 nm and Lch = 180 nm, normalized by the perimeter of the nanowires. A detailed scalability study (VTH, gm, Ids vs. Lch) was carried out. The devices in this study show strong dependence on the nanowire width and smaller nanowire size offers much enhanced electrical performance and better immunity from the short channel effects (SCEs).
    2014 72nd Annual Device Research Conference (DRC); 06/2014
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    ABSTRACT: Although ultra-scaled III-V Gate-all-around (GAA) nanowire (NW) MOSFETs have been studied for their immunity to short channel effects, the degradation mechanisms, such as, hot carrier injection (HCI) in the NW MOSFETs are yet to be studied systematically. In this paper, we examine how HCI affects the NW device performance (ΔVth, ΔSS in both stress and recovery) at different bias conditions, and demonstrate that, unlike positive bias temperature instability (PBTI) in NMOS transistors, the HCI degradation is dominated by charge trapping. We analyze the implications of spatial charge trapping on device performance through experiments and simulation. We find that the distinctive features of HCI degradation of GAA NWs structure can be consistently interpreted by a Sentaurus™-based TCAD simulation.
    2014 IEEE International Reliability Physics Symposium (IRPS); 06/2014
  • Han Liu, Adam T. Neal, Peide D. Ye
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    ABSTRACT: We fabricated field-effect transistors based on few-layer phosphorene. We show a well-behaved back-gate few-layer phosphorene transistor with an on-current of 144 mA/mm, on/off ratio over 104 and hole field-effect mobility of 95.6 cm2/V·s. An ALD Al2O3 top dielectric capping could tune the effective Schottky barrier heights for electrons/holes, and hence change the polarity of the transistor from p-type to ambipolar.
    2014 72nd Annual Device Research Conference (DRC); 06/2014
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    ABSTRACT: Based on the multiple subbands quasi-ballistic transport theory, we investigate the electronic transport of nano size In0.53Ga0.47As nFinFETs with Al2O3 gate dielectric, emphasizing the saturation current region. 1D mobile charge density and gate capacitance density are introduced for the first time to describe the nano-FinFET transport property under volume inversion. With the extracted effective channel mobility of electrons in the linear region from our experiments, the electron mean free path λ in the channel with the value of 5–9 nm is obtained. With only one fitting parameter α = 0.31 for the critical length in the quasi-ballistic transport theory, the calculated drain current can fit all experimental data for various gate voltage V g, source–drain voltage V d, and temperature (240–332 K) in overall very good agreement. The backscattering coefficient r in the saturation region is larger than 0.8, indicating a large room for improvement for the present InGaAs FinFET technology and performance.
    Semiconductor Science and Technology 05/2014; 29(7):075014. DOI:10.1088/0268-1242/29/7/075014 · 2.21 Impact Factor

Publication Stats

4k Citations
602.67 Total Impact Points

Institutions

  • 2005–2015
    • Purdue University
      • • School of Electrical and Computer Engineering
      • • Department of Electrical and Computer Engineering Technology (ECET)
      ウェストラファイエット, Indiana, United States
  • 2014
    • Michigan State University
      • Department of Physics and Astronomy
      Ист-Лансинг, Michigan, United States
  • 2006
    • Princeton University
      • Department of Electrical Engineering
      Princeton, New Jersey, United States
  • 2002–2004
    • Florida State University
      • Department of Physics
      Tallahassee, Florida, United States
  • 2001–2004
    • National High Magnetic Field Laboratory
      Tallahassee, Florida, United States