T. C. Chen

National Taiwan University, Taipei, Taipei, Taiwan

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Publications (6)8.51 Total impact

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    ABSTRACT: In summary, the ~1.5 mum Ge QD MOS LED which is fully compatible with ULSI process is reported for the first time. The origin of the emission is due to the radiative recombination between the electrons and holes confined in the Ge QD. The electrons also recombined with holes at the Si/oxide interface and the band edge light emission from Si is also observed
    01/2006;
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    T. C. Chen, L. S. Lee, W. Z. Lai, C. W. Liu
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    ABSTRACT: The thermal stability of strained Si0.8Ge0.2 and Si devices with HfO2 gate dielectrics prepared by atomic layer chemical vapor deposition is studied. The interfacial layer at the HfO2/Si or HfO2/SiGe interface changed after different annealing temperatures. The thickness of the interfacial layer increases with increasing annealing temperature due to the trace amount of oxygen in the chamber or at the HfO2 dielectric. The capacitance equivalent thickness (CET) increases with increasing post-deposition annealing (PDA) temperature because of the increase of the interfacial layer. The interfacial trap charge densities (Dit) for the SiGe and Si devices with the PDA temperature of 600°C are found to be 7.5×1012 and 1.8×1011cm−2eV−1, respectively. The electrical characteristics of the SiGe device are slightly inferior to the Si device due to the elemental Ge at the HfO2/SiGe interface. Obvious crystallization of HfO2 in SiGe devices with higher annealing temperature causes the raising of leakage current.
    Materials Science in Semiconductor Processing - MATER SCI SEMICOND PROCESS. 01/2005; 8(1):209-213.
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    ABSTRACT: The metal-oxide-silicon light-emitting diode under biaxial tensile mechanical strain is studied. The emission line shape of the device can be fitted by the electron-hole-plasma recombination model. The energy gap of strained Si extracted by the light emission spectra at the temperature of 120 K is reduced by 15 meV under 0.13% biaxial tensile strain. The light intensity of the device under 0.13% biaxial tensile strain increases 9% as compared to the relaxed-Si device. The upshift of valence band edge under mechanical strain to increase the majority hole concentration at the oxide/ Si interface may be responsible for this light emission enhancement. The mechanical strain is measured by Raman spectroscopy, strain gauge, and analyzed by the finite element method. © 2005 American Institute of Physics. Strained Si attracts a great attention recently due to the enhancement of carrier mobility. The substrate strain tech-nology using the lattice misfit between Si and SiGe can yield global biaxial strain, 1,2 but the high cost and high defect density make the substrate strain technology difficult for pro-duction. The biaxial strain also suffers the small hole mobil-ity enhancement at high field. 3 The process-induced strain 4 and package strain 5 can give the strain large enough for mo-bility enhancement with the low cost. The process-induced strain technology has been used in the 90 nm technology node. The strain in Si not only changes the carrier mobility but also changes the band gap and band edges due to the deformation potential. 6,7 The band-gap shrinkage of Ge un-der the tensile strain was reported recently 8,9 based on ab-sorption measurement which probes relatively thick sample. No luminescence results are reported for strained Si or Ge. In this letter, we report the electroluminescence EL from strained-Si using metal-oxide-silicon MOS tunneling di-ode. The radiative recombination of the electron-hole plasma at the accumulation layer of MOS diode can probe the band-gap reduction of Si under strain. Note that the EL is origi-nated at the very thin accumulation layer on the order of nanometer, and can probe the local strain effect, while pho-toluminescence PL is originated from the bulk Si and probes the average strain effect within the absorption length of excitation wavelength on the order of micrometer. The 3 nm oxide used in the MOS tunneling diode is grown by liquid phase deposition LPD at 60 °C on 12 mm 12 mm p-type wafer with the resistance of 1–5 cm. Due to the traps in LPD oxide, the trap-assistant electron tunneling is significant even with 3 nm LPD oxide. At negative bias, the electrons tunnel from the Al gate to p-type silicon, and the holes also tunnel from p-type silicon to Al gate. However, due to the different barrier heights be-tween electrons 3.1 eV and holes 4.6 eV, the hole current is smaller than the electron current. Meanwhile, the negative gate bias also attracts holes in the silicon/oxide in-terface and the electrons can recombine with holes to possi-bly emit light at the accumulation layer. The thickness is measured by ellipsometry. The n-type MOS NMOS diodes have Al gate electrodes with the circular area defined by the shadow mask. Another Al contact is on the back of the wafer.
    Applied Physics Letters 01/2005; 86. · 3.52 Impact Factor
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    ABSTRACT: The electrical and optical reliability characteristics of a Pt/HfO<sub>2</sub> gate stack have been investigated. Incorporating deuterium and hydrogen treatment during post-metallization annealing is employed to improve both the electrical and optical reliability of the Pt/HfO<sub>2</sub> gate stack. For comparison, deuterium-treated technology provides slightly better reliability improvement on both the electrical and optical reliability of Pt/HfO<sub>2</sub> gate stack devices.
    Physical and Failure Analysis of Integrated Circuits, 2004. IPFA 2004. Proceedings of the 11th International Symposium on the; 08/2004
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    ABSTRACT: The metal–insulator–silicon light-emitting diode (MIS LED) using a high-dielectric-constant material (HfO2) is studied. The external quantum efficiency for light emission at room temperature from the MIS LED was observed to be 2.0×10−6, as compared to 0.5×10−6 for the metal–oxide–silicon (MOS) LED. The large hole concentration at the Si/HfO2 interface created by the high dielectric constant of HfO2 may be responsible for the enhancement. The emission line shape of the MIS LED can be fitted by the electron-hole plasma recombination model, similar to the MOS LED. The Al/HfO2/silicon LED with a high interface trap density has a continuous spectrum below the Si gap beside the electron-hole plasma emission, probably due to the radiative recombination between the electrons and holes via the interface states.
    Journal of Applied Physics 06/2004; 95(11). · 2.21 Impact Factor
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    ABSTRACT: A Ge quantum dot photodetector has been demonstrated using a metal-oxide-semiconductor (MOS) tunneling structure. The oxide film was grown by liquid phase deposition (LPD) at 50/spl deg/C. The photodetector with five-period Ge quantum dot has responsivity of 130, 0.16, and 0.08 mA/W at wavelengths of 820 nm, 1300 nm, and 1550 nm, respectively. The device with 20-period Ge quantum dot shows responsivity of 600 mA/W at the wavelength of 850 nm. The room temperature dark current density is as low as 0.06 mA/cm/sup 2/. The high performance of the photodetectors at 820 nm makes it feasible to integrate electrooptical devices into Si chips for short-range optical communication.
    IEEE Electron Device Letters 06/2003; · 2.79 Impact Factor