References of "Nguyen, Ngoc Duy"
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See detailFabrication, characterization, and modeling of strained SOI MOSFETs with very large effective mobility
Driussi, F.; Esseni, D.; Selmi, L. et al

in IEEE (Ed.) 37th European Solid State Device Research Conference (ESSDERC) (2007)

Strained silicon on insulators (sSOI) wafers with a supercritical thickness of 58 nm were produced using thin strain relaxed SiGe buffer layers, wafer bonding, selective etch back and epitaxial overgrowth ... [more ▼]

Strained silicon on insulators (sSOI) wafers with a supercritical thickness of 58 nm were produced using thin strain relaxed SiGe buffer layers, wafer bonding, selective etch back and epitaxial overgrowth. Raman spectroscopy revealed an homogeneous strain of 0.63 plusmn 0.03 % in the strained Si layer. Long channel n-type SOI-MOSFETs showed very large electron mobilities up to 1200 cm2/Vs in the strained Si devices. These values are more than two times larger than those of reference SOI n-MOSFETs. Mobility simulations with state of the art scattering models are then used to interpret the experiments. [less ▲]

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See detailStrained silicon-on-insulator - Fabrication and characterization
Reiche, M.; Himcinschi, C.; Gösele, U. et al

in 211th ECS Meeting, 2007 (2007)

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See detailIn-line characterization of heterojunction bipolar transistor base layers by high-resolution x-ray diffraction
Nguyen, Ngoc Duy ULg; Loo, R.; Hikavyy, A. et al

in ECS Transactions (2007), 10

The suitability of high-resolution X-ray diffraction (HRXRD) as an in-line measurement tool for the characterization of heterojunction bipolar transistor SiGe base layers and Si cap layers was ... [more ▼]

The suitability of high-resolution X-ray diffraction (HRXRD) as an in-line measurement tool for the characterization of heterojunction bipolar transistor SiGe base layers and Si cap layers was investigated. We showed that despite of polycrystalline Si on the mask material of patterned wafers, HRXRD measurements performed on an array of small windows yield results which are comparable to those that were obtained on a window which is larger than the size of the source beam, regarding the thickness and the Ge content of the SiGe layers. The possibility to extract layer parameters for active device windows of different sizes was therefore demonstrated. The suitability of HRXRD for in-line measurement of the Si cap thickness was also assessed and the sensitivity of this technique for determining the substitutional boron concentration in SiGe was studied. The detection limit in the monitoring of the active dopant concentration was about 2.7 × 1019 cm-3. [less ▲]

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See detailStrained silicon-on-insulator - Fabrication and characterization
Reiche, M.; Himcinschi, C.; Gösele, U. et al

in ECS Transactions (2007), 6

SSOI substrates were successfully fabricated using He+ ion implantation and annealing to relax thin (< 500nm) SiGe buffer layers, bonding and layer transfer processes to realize strained-Si layers onto ... [more ▼]

SSOI substrates were successfully fabricated using He+ ion implantation and annealing to relax thin (< 500nm) SiGe buffer layers, bonding and layer transfer processes to realize strained-Si layers onto oxide layers. The reduced thickness of the SiGe buffer possess numerous advantages such as reduced process costs for epitaxy and for reclaim of the handle wafer if the layer splitting is initiated in the SiGe/Si interface. The electron mobilities in the fabricated SSOI layers were measured using transistors with different gate lengths. An electron mobility of ~530 cm2 /Vs was extracted, being much higher than in non-strained SOI substrates. Furthermore, an 80% drive current (IDSAT) improvement has been measured for long channel devices. [less ▲]

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See detailLarge current enhancement in n-MOSFETs with strained Si on insulator
Mantl, S.; Buca, D.; Zhao, Q. et al

in International Semiconductor Device Research Symposium, 2007 (2007)

As scaling of the critical transistor dimensions below 65 nm has been slowed down, the implementation of novel materials, especially high mobility channel materials is most attractive to boost the ... [more ▼]

As scaling of the critical transistor dimensions below 65 nm has been slowed down, the implementation of novel materials, especially high mobility channel materials is most attractive to boost the transistor performance. Applying strain to silicon has become a successful route. The electron mobility can be enhanced by biaxial strain introduced into Si by epitaxial growth of Si on a strain relaxed SiGe layer or by so called process induced methods applied directly on transistor level. The combination of strained Si and SOI is particularly promising due to the combination of the enhanced mobilities and the inherent advantages of SOI. First long channel n-MOSFETs with gate lengths of 5 to 50 mum and a 6.6 nm thick SiO2 gate dielectric were fabricated. For comparison, devices on unstrained SOI were made. The transfer characteristics of a fully depleted sSOI-MOSFET with a gate length of 5 mum and a gate width of 20 mum indicating an inverse sub-threshold slope of 75mV/dec. [less ▲]

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See detailStrained Si-on-insulator for advanced CMOS devices
Mantl, S.; Buca, D.; Zhao, Q. et al

Poster (2007)

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See detailLow-temperature chemical vapor deposition of highly-doped n-type epitaxial Si at high growth rate
Nguyen, Ngoc Duy ULg; Loo, Roger; Caymax, Matty

Conference (2007)

We investigated the growth of in-situ n-type doped epitaxial Si layers with arsenic and phosphorus by means of low-temperature chemical vapor deposition using trisilane as Si-precursor. Indeed, in order ... [more ▼]

We investigated the growth of in-situ n-type doped epitaxial Si layers with arsenic and phosphorus by means of low-temperature chemical vapor deposition using trisilane as Si-precursor. Indeed, in order to prevent the alteration of the characteristics of the devices which are already present on the wafer, an epitaxy process at low temperature is highly desired for applications such as BiCMOS. In this work, the varying parameters are the deposition temperature, the Si-precursor mass flow and the dopant gas flow. As a result, a process for the deposition of heavily doped epilayers was demonstrated at 600 °C with high deposition rate, which is important for maintaining high throughput and low process cost. We showed that using trisilane as a Si-precursor resulted in a much more linear n-type doping behavior than using dichlorosilane. Therefore it allowed an easier process control and a wider dynamic doping range. Our process is an interesting route for the epitaxy of a low-resistance emitter layer for bipolar transistor application. [less ▲]

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See detailEnhancement of the relaxation of SiGe layers by He ion implantation using a delta-Si:C layer
Buca, D.; Goryll, M.; Holländer, B. et al

Conference (2007)

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See detailAdmittance spectroscopy of semiconductor systems
Nguyen, Ngoc Duy ULg

Scientific conference (2006, September 11)

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See detailNumerical simulation of impedance and admittance of OLEDs
Nguyen, Ngoc Duy ULg; Schmeits, Marcel

in Physica Status Solidi : A. Applications and Materials Science (2006), 203

The electrical characteristics of organic light-emitting devices are calculated for the dc and ac regimes by numerically solving the basic semiconductor equations under steady-state and small-signal ... [more ▼]

The electrical characteristics of organic light-emitting devices are calculated for the dc and ac regimes by numerically solving the basic semiconductor equations under steady-state and small-signal conditions. For a given structure, the dc and ac electric potential and electric field, the electron and hole concentrations, as well as the different components of the current density are obtained as function of the one-dimensional spatial coordinate. This approach allows a detailed microscopic description of the dependencies of these quantities on the applied steady-state voltage V0 and the frequency of the modulating voltage. The final output consists in the frequency-dependent complex admittance and impedance of the device, the real and imaginary parts of which are the experimentally-available data. As a typical example, we show the results for a two-layer structure where α-NPD is the hole-transporting material and Alq3 the electron-transporting material. The anode is made of ITO and Al/LiF composes the cathode. The admittance and impedance curves, yielded by the numerical simulation as functions of the modulation frequency, are fitted by an equivalent electrical circuit, the elements of which are resistances and capacitances. The number of com- ponents depends on the structure composition and on the applied steady-state voltage. We show that each element can be associated with a particular region of the device. This allows to correlate the dependence of each feature of the admittance and impedance curves with one or several parameters describing the ma- terial system. Such an analysis can be useful for the inverse approach, where, starting from measurements of the electrical ac characteristics, the aim is to get information on the microscopic mechanisms which contribute to the electrical conduction of the device. [less ▲]

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See detailAdmittance spectroscopy of semiconductor structures
Nguyen, Ngoc Duy ULg

Scientific conference (2006)

Admittance spectroscopy is a powerful tool for electrical characterization of semiconductor structures such as p-n junctions, Schottky diodes, light-emitting systems or quantum wells. It consists in ... [more ▼]

Admittance spectroscopy is a powerful tool for electrical characterization of semiconductor structures such as p-n junctions, Schottky diodes, light-emitting systems or quantum wells. It consists in monitoring the complex admittance of the overall device under test as a function of frequency, applied dc voltage and temperature. This technique gives direct access to the emission-capture processes occurring between an impurity level and the conduction or the valence band and leads to the determination of important electronic properties including the activation energy and the carrier capture cross sections. However, the interpretation of the admittance curves is straightforward only under restrictive assumptions such as full ionization of the shallow dopant, with a concentration larger than the deep impurity concentration. Numerical simulations, based on the solution of the basic semiconductor equations, allow to carry out a detailed analysis of the steady-state and small-signal electrical characteristics of the systems and thus contribute to a better understanding of the conduction mechanisms and of the microscopic origin of the features in the experimental admittance spectra. In this presentation, the results obtained for three different structures are shown in order to illustrate the method. In the first case, the role of Mg in GaN Schottky diodes is investigated. The results of the study show that this acceptor has simultaneously the functions of dopant and of deep impurity. In order to explain the electrical behavior of Mg, thermal admittance spectroscopy measurements are performed on Schottky structures based on Mg-doped GaN layers grown by metalorganic vapor phase epitaxy on sapphire. The analysis is carried out by simulating the electrical characteristics of the device. The calculated curves fully reproduce the experimental results and the microscopic parameters are determined by an optimized fitting procedure, based on the comparison of the electrical characteristics obtained from the numerical simulations to those of the experiment. In the second example, charge-carrier mobility in organic materials is evaluated. The frequency- dependent complex admittance and impedance of the structure consisting of the organic layer, grown by thermal evaporation and sandwiched by metallic electrodes, are measured as functions of the dc bias. The capacitance-versus-frequency curve exhibits a minimum, the frequency-position of which increases with the applied dc voltage. Based on numerical calculations, the theoretical analysis shows that the inductive contribution to the capacitance originates from the modulation of the free carrier concentration in the organic material. The finite carrier transit time determines the frequency-response of the structure. Moreover, the low-frequency behavior of the capacitance curves can be explained by the presence of a band of defect states that modifies the charge distribution within the device. As third application of the admittance spectroscopy method, the electrical characteristics of an organic light-emitting diode are numerically simulated for the dc and the ac regimes. This approach allows to obtain a detailed microscopic description of the dependences of the carrier concentrations and current densities on the applied steady-state voltage and the modulation frequency. The fitting of the resulting admittance and impedance curves to the response of an equivalent electrical circuit shows that each element can be associated with a particular region of the structure. It is then possible to correlate the dependence of each feature of the admittance and impedance curves with one or several parameters of the material system. [less ▲]

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See detailAdmittance spectroscopy of OLEDs
Nguyen, Ngoc Duy ULg; Schmeits, Marcel

Scientific conference (2005, December 12)

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See detailSmall-signal characteristics of organic semiconductors with continuous energy distribution of traps
Schmeits, Marcel; Nguyen, Ngoc Duy ULg

in Physica Status Solidi A. Applications and Materials Science (2005), 202(2764),

The electrical characteristics of organic light emitting devices containing a continuous distribution of trap states in the forbidden gap are obtained by numerically solving the basic semiconductor ... [more ▼]

The electrical characteristics of organic light emitting devices containing a continuous distribution of trap states in the forbidden gap are obtained by numerically solving the basic semiconductor equations for the steady state and under small-signal conditions. The spatially-dependent occupied trap states, which are described by an explicit density of states function, modify the charge distribution within the structure and the shape of the electric field and the carrier current densities. The effect of the modulation frequency, the applied voltage and the device temperature are studied for a hole conducting layer with a trap density of states consisting of a double gaussian profile and for a given set of microscopic parameters including the carrier mobilities and thermal velocities, the capture cross sections, and the residual shallow impurity concentration. The frequency-dependent loss and capacitance curves are obtained for various experimental conditions, like temperature and applied steady-state voltage. Effects of parameters describing electrical contacts and trap density of states are shown. Such results are particularly useful for the analysis of experimental electrical characteristics obtained by thermal admittance spectroscopy. [less ▲]

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See detailPhotorefractive ZnTe grown by traveling heater method
Verstraeten, David; Launay, Jean-Claude; Delaye, Philippe et al

in Trends in Optics and Photonics (2003), 87

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See detailElectrical characterization of InGaN/GaN multiple-quantum-well structures by thermal admittance spectroscopy
Nguyen, Ngoc Duy ULg; Schmeits, Marcel; Germain, Marianne et al

in Physica Status Solidi C. Current Topics in Solid State Physics (2002)

Experimental results of electrical characterization of InGaN/GaN multiple-quantum-well electrolu- minescence test structures obtained by thermal admittance spectroscopy are presented. The stu- died GaN ... [more ▼]

Experimental results of electrical characterization of InGaN/GaN multiple-quantum-well electrolu- minescence test structures obtained by thermal admittance spectroscopy are presented. The stu- died GaN : Mg/5 × (InGaN/GaN)/GaN:Si structures were grown on c-plane sapphire substrate by metal-organic vapor phase epitaxy. Admittance measurements were conducted from room tem- perature down to 125 K for a wide frequency range and for different applied bias voltages. Analy- sis of the capacitance versus frequency curves shows the presence of several cutoff frequencies which originate from the response of equivalent RC series circuits and give peaks in the conduc- tance divided by angular frequency. The dependence of the position and the amplitude of these peaks on temperature is discussed. [less ▲]

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See detailThe photorefractive effect at large modulation depth in semiconductors with multiple defect levels
Nguyen, Ngoc Duy ULg; Schmeits, Marcel ULg

in Applied Physics B : Lasers & Optics (2002), 74

The photorefractive effect in semiconducting mate- rials with multiple defects is studied in the case of modulation depth m = 1. The basic equations are Poisson's equation and the continuity equations for ... [more ▼]

The photorefractive effect in semiconducting mate- rials with multiple defects is studied in the case of modulation depth m = 1. The basic equations are Poisson's equation and the continuity equations for electrons, holes and occupied defect levels. They include all recombination and optical generation mechanisms between the defect levels and valence and conduc- tion bands. Their explicit numerical solution yields microscopic quantities such as space- and time-dependent electrical field profiles, carrier concentrations, as well as generation and re- combination rates. The fundamental Fourier component of the electric field yields the two-wave-mixing gain. Application is made for InP with two levels in the forbidden gap, for which steady-state and transient resulting quantities are shown. The re- sulting features at large modulation depth are of non-sinusoidal shape. Due to the complexity of the system, the final results strongly depend on all parameters intervening in the models used, as is illustrated for several typical cases. [less ▲]

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See detailElectrical characterization of InGaN/GaN multiple-quantum-well structures by thermal admittance spectroscopy
Nguyen, Ngoc Duy ULg; Schmeits, Marcel; Germain, Marianne et al

Poster (2002)

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