Showing papers on "Induced high electron mobility transistor published in 2006"
TL;DR: In this article, room temperature electron mobility of 1170cm2∕Vs is obtained in an undoped, lattice-matched, Al0.82In0.18N∕GaN field effect transistor heterostructure.
Abstract: Room temperature electron mobility of 1170cm2∕Vs is obtained in an undoped, lattice-matched, Al0.82In0.18N∕GaN field-effect transistor heterostructure, while keeping a high (2.6±0.3)×1013cm−2 electron gas density intrinsic to the Al0.82In0.18N∕GaN material system. This results in a two-dimensional sheet resistance of 210Ω∕◻. The high mobility of these layers, grown by metal-organic vapor phase epitaxy on sapphire substrate, is obtained thanks to the insertion of an optimized AlN interlayer, reducing the alloy related interface roughness scattering.
311 citations
TL;DR: In this paper, organic n-channel field effect transistors and circuits based on C60 films grown by hot wall epitaxy were investigated and the electron mobility was found to be dependent strongly on the substrate temperature during film growth and on the type of the gate dielectric employed.
Abstract: We report on organic n-channel field-effect transistors and circuits based on C60 films grown by hot wall epitaxy. Electron mobility is found to be dependent strongly on the substrate temperature during film growth and on the type of the gate dielectric employed. Top-contact transistors employing LiF∕Al electrodes and a polymer dielectric exhibit maximum electron mobility of 6cm2∕Vs. When the same films are employed in bottom-contact transistors, using SiO2 as gate dielectric, mobility is reduced to 0.2cm2∕Vs. By integrating several transistors we are able to fabricate high performance unipolar (n-channel) ring oscillators with stage delay of 2.3μs.
254 citations
TL;DR: An n-type InAs/InAsP heterostructure nanowire field-effect transistor has been fabricated and compared with a homogeneous InAs field- effect transistor, and a high electron mobility of 1500 cm2/Vs is deduced.
Abstract: An n-type InAs/InAsP heterostructure nanowire field-effect transistor has been fabricated and compared with a homogeneous InAs field-effect transistor. For the same device geometry, by introduction...
155 citations
TL;DR: In this article, a single-grain organic field-effect transistor (OFET) with a 1μm channel length of top-contact electrodes is demonstrated in a wide range of temperatures from 300 down to 5.8K.
Abstract: A single-grain organic field-effect transistor (OFET) of pentacene with a 1μm channel length of top-contact electrodes is demonstrated in a wide range of temperatures from 300 down to 5.8K. No hysteresis behavior was observed in the transfer characteristics throughout the entire temperature range. The saturation mobility and on/off ratio are estimated at 1.11cm2∕Vs and 107 at 300K and 0.34cm2∕Vs and 105 at 5.8K, respectively. The nonmonotonic temperature dependence of the mobility indicates a bandlike transport at high temperatures. The electric-field dependence of the mobility in the single-grain OFET does not show a Poole-Frenkel-like behavior. This indicates that Poole-Frenkel-like behavior observed in conventional OFETs can be attributed to the disorder of molecules; single-grain OFET is free from such disorders.
110 citations
TL;DR: In this paper, a two-dimensional electron gas was observed in Zn polar ZnMgO∕ZnO (ZnmgO on ZnO) heterostructures grown by radical source molecular beam epitaxy.
Abstract: A two-dimensional electron gas was observed in Zn polar ZnMgO∕ZnO (ZnMgO on ZnO) heterostructures grown by radical source molecular beam epitaxy. The electron mobility of the ZnMgO∕ZnO heterostructures dramatically increased with increasing Mg composition and the electron mobility (μ∼250cm2∕Vs) at RT reached a value more than twice that of an undoped ZnO layer (μ∼100cm2∕Vs). The carrier concentration in turn reached values as high as ∼1×1013cm−2 and remained nearly constant regardless of Mg composition. Strong confinement of electrons at the ZnMgO∕ZnO interface was confirmed by C-V measurements with a concentration of over 4×1019cm−3. Temperature-dependent Hall measurements of ZnMgO∕ZnO heterostructures also exhibited properties associated with well defined heterostructures. The Hall mobility increased monotonically with decreasing temperature, reaching a value of 2750cm2∕Vs at 4K. Zn polar “ZnMgO on ZnO” structures are easy to adapt to a top-gate device. These results open new possibilities for high elec...
109 citations
TL;DR: In this article, a low on-resistance and high breakdown-voltage enhancement-mode (E-mode) AlGaN/AlN/GaN high electron mobility transistor (HEMT) was fabricated without the recessed-gate process.
Abstract: A low on-resistance and high-breakdown-voltage enhancement-mode (E-mode) AlGaN/AlN/GaN high electron mobility transistor (HEMT) was fabricated without the recessed-gate process. A thin AlGaN barrier layer (4.5 nm) was used for the normally-off operation. In order to decrease the on-state resistance, two different techniques are used. One is the side-ohmic contact, which has a low contact resistance, due to the direct contact with the two-dimensional electron gas (2DEG). The other is SiO2 passivation, which induces the sheet carriers and decreases the sheet resistance. As a result, an on-state resistance of 1.9 mΩcm2 and an off-state breakdown voltage of 610 V were achieved for the E-mode HEMT within a threshold voltage of approximately -0.1 V.
104 citations
TL;DR: In this article, a low-operating-voltage organic field-effect transistor was realized by using the cross-linked cyanoethylated poly(vinyl alcohol) (CR-V) as a gate dielectric.
Abstract: Low-operating-voltage organic field-effect transistor has been realized by using the cross-linked cyanoethylated poly(vinyl alcohol) (CR-V) as a gate dielectric. The cross-linked CR-V dielectric was found to have a high dielectric constant of 12.6 and good insulating properties, resulting in a high capacitance (92.9nF∕cm2 at 20Hz) for a dielectric thickness of 120nm. A pentacene field-effect transistor fabricated with the cross-linked CR-V dielectric was found to exhibit a high carrier mobility (0.62cm2∕Vs), a small subthreshold swing (185mV∕decade), and little hysteresis at low operating voltages (⩽−3V).
92 citations
TL;DR: In this article, an organic field effect transistors (OFET) with both the mobility and the charge density have high values of 0.1 cm(2)/V s and 28 mC/m(2), respectively.
85 citations
TL;DR: In this paper, the open-gate AlGaN∕GaN high electron mobility transistor (HEMT) structures were investigated in aqueous solutions and polar liquids, and the sensitivity for the potential change was 57.5mV∕pH, very close to the theoretical value of 58.9mVΩpH at 24°C for the Nernstian response to H+ ions.
Abstract: Liquid-phase sensing characteristics of open-gate AlGaN∕GaN high electron mobility transistor (HEMT) structures were investigated in aqueous solutions and polar liquids. In de-ionized water, the open-gate HEMT clearly showed good drain I-V characteristics with current saturation and pinch-off behavior, very similar to I-V characteristics of typical Schottky-gate HEMTs. We observed a fine parallel shift in the transfer curves according to change in the pH value in a solution, indicating the corresponding potential change at the AlGaN surface. The sensitivity for the potential change was 57.5mV∕pH, very close to the theoretical value of 58.9mV∕pH at 24°C for the Nernstian response to H+ ions. In the low drain bias region, the drain current linearly decreased with the pH value. This also indicated a systematic potential change at the AlGaN surface due to pH change. The present open-gate device showed a fast response to the pH change and a stable operation at fixed pH values. A possible mechanism for the pH r...
68 citations
Patent•
18 Sep 2006TL;DR: In this article, a novel enhancement mode field effect transistor (FET) was proposed, which has an N-polar surface using polarization fields to reduce the electron population under the gate in the Npolar orientation, has improved dispersion suppression, and low gate leakage.
Abstract: A novel enhancement mode field effect transistor (FET), such as a High Electron Mobility Transistors (HEMT), has an N-polar surface uses polarization fields to reduce the electron population under the gate in the N-polar orientation, has improved dispersion suppression, and low gate leakage.
65 citations
TL;DR: In this paper, a compact electron mobility model based on the well-established Lombardi mobility model was proposed to reproduce the mobility degradation commonly observed in these SiC devices using 2D electrical simulations along with the proposed model and taking into account interface traps Coulomb scattering.
TL;DR: A GaN/ultrathin AlN∕GaN heterojunction has been used to introduce a GaN spacer between the GaN channel and the AlGaN barrier in high electron mobility transistors (HEMTs).
Abstract: A GaN/ultrathin AlN∕GaN heterojunction has been used to introduce a GaN spacer between the GaN channel and the AlGaN barrier in AlGaN∕GaN high electron mobility transistors (HEMTs). In conventional AlGaN∕GaN devices, the alloy scattering of the electrons with the AlGaN barrier degrades the electron velocity at high electric fields. This effect is significantly reduced in GaN-spacer transistors, which therefore have much better high field transport properties. While the dc performance of these transistors is similar to conventional AlGaN∕GaN HEMTs, a 20% increase in the electron velocity has been measured by two different techniques.
TL;DR: In this article, a thermal model of AlGaN∕GaN high electron mobility transistors (HEMTs) has been developed based on a quasi-two-dimensional numerical solution of Schrodinger's equation coupled with Poisson's equation.
Abstract: A thermal model of AlGaN∕GaN high electron mobility transistors (HEMTs) has been developed based on a quasi-two-dimensional numerical solution of Schrodinger’s equation coupled with Poisson’s equation. The static current characteristics of HEMT devices have been obtained with the consideration of the self-heating effect on related parameters including polarization, electron mobility, saturation velocity, thermal conductivity, drain and source resistance, and conduction-band discontinuity at the interface between AlGaN and GaN. The simulation results agree well with our experimental data. It has also been demonstrated that the reduction of the saturation drain current at high power dissipation is primarily due to the decrease of electron mobility in the channel. The proposed model is valuable for predicting and evaluating the performance of different device structures and packages for various applications.
TL;DR: In this article, a semi-insulating GaN buffer layer was developed for AlGaN∕GaN high electron mobility transistor (HEMT) applications on sapphire substrates.
Abstract: Semi-insulating character (sheet resistivity of 3.26×1011Ω∕sq) of thick GaN layers was developed for AlGaN∕GaN high electron mobility transistor (HEMT) applications on an AlN buffer layer. Electrical and structural properties were characterized by a dark current-voltage transmission line model, x-ray diffraction, and atomic force microscope measurements. The experimental results showed that compared to semi-insulating GaN grown on low temperature GaN nucleation, the crystal quality as well as surface morphology were remarkably improved. It was ascribed to the utilization of a high quality insulating AlN buffer layer and the GaN initial coalescence growth mode. Moreover, the significant increase of electron mobility in a HEMT structure suggests that this is a very promising method to obtain high performance AlGaN∕GaN HEMT structures on sapphire substrates.
TL;DR: In this article, the use of AlGaN∕GaN high electron mobility transistor (HEMT) differential sensing diodes is shown to provide robust detection of 1% H2 in air at 25°C.
Abstract: The use of AlGaN∕GaN high electron mobility transistor (HEMT) differential sensing diodes is shown to provide robust detection of 1% H2 in air at 25°C. The active device in the differential pair is coated with 10nm of Pt to enhance catalytic dissociation of molecular hydrogen, while the reference diode is coated with Ti∕Au. The active diode in the pair shows an increase in forward current of several milliamperes at a bias voltage of 2.5V when exposed to 1% H2 in air. The HEMT diodes show a response approximately twice that of GaN Schottky diodes, due to the presence of piezoelectric and spontaneous polarization in the heterostructure. The use of the differential pair removes false alarms due to ambient temperature variations.
TL;DR: In this article, three types of field effect transistors have been studied: thin film transistor, transistor prepared by placing a single crystal flake on a substrate and transistor fabricated on a single single crystal by depositing electrodes and insulating layer onto it.
TL;DR: In this paper, the authors demonstrated theoretically that compensation of the built-in electric field in AlN∕GaN ∕AlN heterostructures with the externally applied perpendicular electric field may lead to the increase of the in-plane electron drift mobility.
Abstract: The authors demonstrated theoretically that compensation of the built-in electric field in AlN∕GaN∕AlN heterostructures with the externally applied perpendicular electric field may lead to the increase of the in-plane electron drift mobility. It has been shown that two- to fourfold increase of the room temperature mobility can be achieved for both nondegenerate and degenerate electron densities. Their calculations clarified the role of the intersubband electron transitions mediated by optical phonons in limiting the carrier mobility in GaN-based heterostructures. The tuning of the electron mobility with the perpendicular electric field may impact design of the high-power GaN∕AlGaN heterostructure field-effect transistors.
TL;DR: In this article, the electron mobility in AlGaN alloys as a function of the alloy composition was analyzed and local bulk mobility values for different Alloy compositions were found, and electron mobility was deduced.
Abstract: Polarization gradients in graded AlGaN alloys induce bulk electron distributions without the use of impurity doping. Since the alloy composition is not constant in these structures, the electron scattering rates vary across the structure. Capacitance and conductivity measurements on field effect transistors were used to find mobility as a function of depth. The effective electron mobility at different depths calculated from theory closely matched the measured mobility. Local bulk mobility values for different AlGaN compositions were found, and the electron mobility in AlGaN as a function of alloy composition was deduced. These were found to match with theoretical calculations.
TL;DR: In this paper, an electronic method for analyzing the transient response of a pentacene organic field effect transistor at time scales below 100ns is presented with analysis that allows extraction of estimated field-dependent device mobility from the measured carrier velocity.
Abstract: An electronic method for analyzing the transient response of a pentacene organic field effect transistor at time scales below 100ns is presented with analysis that allows extraction of estimated field-dependent device mobility from the measured carrier velocity. A second technique we propose is the use of T-SPICE simulations of transient response data of the device behavior between ∼100ns and ∼3μs. These results are compared with lower field-effect mobilities extracted from the transient data at 250μs and the dc drain current (Id) versus source-drain voltage (Vds) characteristics in the saturation regime. This trend of decreasing mobility with increasing time is perhaps due to the absence of the bias stress effect at small time scales.
TL;DR: In this article, magnetoresistance technique is used to perform mobility measurements in Fully-Depleted Silicon-on-Insulator (FDSOI) MOSFETs, which has the advantage of allowing channel mobility measurement from weak to strong inversion without requiring the knowledge of the transistor's effective channel length.
Abstract: Ultra-thin Silicon-on-Insulator (SOI) transistor has proved to offer advantages over bulk MOSFETs for high-speed, low power applications However, there is still a strong need to obtain an accurate understanding of carrier transport and mobility behaviour in these advanced devices In this work, magnetoresistance technique is used to perform mobility measurements in Fully-Depleted Silicon-on-Insulator (FDSOI) MOSFETs This technique has the advantage of allowing channel mobility measurement from weak to strong inversion without requiring the knowledge of the transistor’s effective channel length The influence of different scattering mechanisms in the channel is investigated in details by obtaining mobility values at low temperatures A new differential method enabling mobility extraction from pure channel magnetoresistance corrected for source–drain series resistance is presented After the correction, in devices with large series resistance an increase in the extracted mobility is obtained in strong inversion, where the channel resistance is small and conventional mobility extraction is most affected by the impact of series resistance
TL;DR: In this article, the effects of dislocations and Si doping on the electrical properties of n-type GaN grown by metal organic chemical vapor deposition (MOCVD) are investigated.
Abstract: The effects of dislocations and Si doping on the electrical properties of n-type GaN grown by metal organic chemical vapor deposition (MOCVD) are investigated. It is found that both electron mobility and carrier concentration are strongly influenced by edge dislocations. A moderate Si doping during the GaN growth improves the electron mobility, but the best doping effect depends on the dislocation density of the sample. High quality about 4-μm-thick MOCVD-grown GaN film with a room temperature electron mobility as high as 1005cm2∕Vs is obtained by optimizing growth conditions.
01 Oct 2006
TL;DR: In this paper, the mechanism responsible for short-channel electron mobility (e$mobility) abnormal degradation in n-type tall fins multiple-gate field effect transistors (MuGFETs) has been identified.
Abstract: The mechanism responsible for the short-channel electron mobility (e$mobility) abnormal degradation in n-type tall fins multiple-gate field-effect transistors (MuGFETs) has been identified. RF-CV measurement, mobility extraction, and 1/f noise measurements have been performed and point to a larger process related density of traps (N t) at the gate edges. These traps and their distribution along the channel give a common and consistent explanation for the channel dependence of the mobility and the normalized noise degradation and for the threshold voltage roll off
TL;DR: In this article, the authors show that the electron mobility can be strongly enhanced in AlN ∕GaN∕AlN heterostructures with the shallow InxGa1−xN channel in the middle of the potential well.
Abstract: The authors show that the electron mobility can be strongly enhanced in AlN∕GaN∕AlN heterostructures with the shallow InxGa1−xN channel—nanogroove—in the middle of the potential well. The modified heterostructure has the room-temperature electron mobility, which is five times larger than that in conventional quantum wells. The maximum mobility enhancement is achieved for In content x≈0.05, which is sufficient to weaken the intersubband electron scattering without leading to the substantial electron—interface-phonon scattering. The mobility enhancement is pronounced for a wide range of the carrier densities (1011–1013cm−2), which is important for GaN technology.
TL;DR: In this paper, an Al layer as thin as 3 nm was inserted between the AlGaN barrier layer and the gate contact, which showed significant improvement in capacitance-gate voltage characteristics especially at a low frequency as well as drastic reduction in gate leakage current.
Abstract: To improve an AlGaN∕GaN high electron mobility transistor, an Al layer as thin as 3 nm was inserted between the AlGaN barrier layer and the gate contact. At our preceded experiments on Schottky diodes, we confirmed significant improvement in capacitance-gate voltage characteristics especially at a low frequency as well as drastic reduction in gate leakage current, which should be interpreted in terms of decrease in oxygen-related trap density at the AlGaN surface. As a result of the trap reduction, the transistor indicates marked improvement of current collapse with no degradation in transconductance.
TL;DR: An interesting hydrogen sensor based on an Al/sub 024/Ga/ sub 076/As Schottky barrier high-electron mobility transistor with a catalytic Pd metal/oxide/semiconductor is fabricated and demonstrated in this paper.
Abstract: An interesting hydrogen sensor based on an Al/sub 024/Ga/sub 076/As Schottky barrier high-electron mobility transistor with a catalytic Pd metal/oxide/semiconductor is fabricated and demonstrated In comparison with traditional Schottky diodes or capacitance-voltage type hydrogen sensors, the studied device exhibits larger current variation, lower hydrogen detection limit, and shorter transient hydrogen response time Besides, good hydrogen-sensing properties, such as significant drain current change, threshold voltage shift, and transconductance change of transistor behaviors, are obtained Therefore, the studied device provides the promise for high-performance solid-state hydrogen sensors, optoelectronic integrated circuits, and microelectromechanical system applications
TL;DR: In this paper, the effect of growth temperature of the AlGaAs spacer layer on mobility in a two-dimensional electron gas in single-side δ-doped pseudomorphic AlgaAs/InGaAs/GaAs transistor structures with a high electron mobility is studied experimentally.
Abstract: The effect of growth temperature of the AlGaAs spacer layer on mobility in a two-dimensional electron gas μ
e
in single-side δ-doped pseudomorphic AlGaAs/InGaAs/GaAs transistor structures with a high electron mobility is studied experimentally. The energy-band diagram is analyzed using a self-consistent calculation. In order to study the electronic transport properties, an optimized structure in which there is no parallel conduction over the doped layer was chosen. It is shown that, in optimized structures, the mobility μ
e
increases by 53% at T = 300 K and by 69% at T = 77 K as the growth temperature increases from 590 to 610°C, with the other parameters and the growth conditions remaining the same. It is assumed that this behavior is related to an improvement in the structural quality of the AlGaAs spacer layer and the AlGaAs/InGaAs/GaAs heteroboundary.
TL;DR: In this paper, a two-dimensional electron heterostructure field effect device was proposed to display high mobility electron transport using a high efficacy contacting scheme and simple metallic overlapping gate, obviating dopant layers.
Abstract: The authors present a two-dimensional electron heterostructure field effect device of simplistic design and ease of fabrication that displays high mobility electron transport. This is accomplished using a high efficacy contacting scheme and simple metallic overlapping gate, obviating dopant layers. The resultant devices demonstrate adjustable electron densities and mobilities larger than 8×106cm2∕Vs at the highest densities of 2.4×1011∕cm2. This device type provides an experimental avenue for studying electron correlations and may answer demands for routine fabrication of practical high electron mobility transistors.
TL;DR: In this paper, an electronic method to measure the drift velocity and mobility of charge carriers in polymer thin film transistor has been developed, based on the movement of a packet of carriers injected into the channel.
Abstract: An electronic method to measure the drift velocity and mobility of charge carriers in polymer thin film transistor has been developed. The measurement is based on the movement of a packet of carriers injected into the channel. This technique can be used to explore trap states and therefore obtain a comprehensive understanding of charge transport in these materials. Drift mobility of 0.52cm2∕Vs is obtained from the transit time which is a factor of 3 higher than the field-effect transistor mobility.
TL;DR: In this article, the thermal threshold coefficients of a symmetrically graded δ-doped InAlAs∕InxGa1−xAs ∕GaAs (x=0.65→0.5) metamorphic high electron mobility transistor (MHEMT) have been investigated.
Abstract: High-temperature threshold characteristics of a symmetrically graded δ-doped InAlAs∕InxGa1−xAs∕GaAs (x=0.5→0.65→0.5) metamorphic high electron mobility transistor (MHEMT) have been investigated. The thermal threshold coefficients, defined as ∂Vth∕∂T, are superiorly low at 0.9mV∕K from 300to420K and at −0.75mV∕K from 420to500K. An interesting polarity change of the thermal threshold coefficient was observed around 420K due to the variation of thermal modulation effects. The present MHEMT device, with stabilized thermal threshold variations and superior high-temperature linearity characteristics, is promising for high-temperature circuit applications.
TL;DR: In this paper, the background charge fluctuators near an Al-AlOx-Al single-electron transistor on an oxidized Si substrate were observed to be located very near the oxide surface.
Abstract: We present observations of background charge fluctuators near an Al–AlOx–Al single-electron transistor on an oxidized Si substrate. The transistor design incorporates a heavily doped substrate and top gate, which allow for independent control of the substrate and transistor island potentials. Through controlled charging of the Si∕SiO2 interface we show that the fluctuators cannot reside in the Si layer or in the tunnel barriers. Combined with the large measured signal amplitude, this implies that the defects must be located very near the oxide surface.