Influence of a carrier supply layer on carrier density and drift mobility of AlGaN/GaN/SiC high-electron-mobility transistors

Marso, Michel; Bernát, J.; Javorka, P.; Kordoš, P.

doi:10.1063/1.1704854

Cited by 21 publications

(17 citation statements)

References 11 publications

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“…The low current level in I DS is mostly due to smaller contact area and ohmic contact formation. Utilizing a negative gate bias ( V GS ), the piezoresistive effect is translated into a piezotransistive effect where the 2DEG carrier concentration ( n s ) 27 is reduced, thus primarily increasing the Δ n s / n s ratio (Δ n s is the change in 2DEG concentration due to strain caused by deflection of the cantilever). Figure 2b shows the gate bias dependence of the 2DEG density, which was obtained for a particular gate bias by integrating the C – V characteristic.…”

Section: Resultsmentioning

confidence: 99%

“… 24 ), the ratio Δ n s / n s will increase as the gate voltage becomes more negative and vice versa . Since μ int also decreases with reduced n int (due to increased scattering) 27 , the ratio Δ μ int / μ int will also increase with more negative gate voltage, causing Δ ρ int / ρ int to increase strongly as V GS becomes more negative. Clearly, to maximize Δ ρ int / ρ int , which ultimately controls the sensitivity, appropriate choice of V GS is very important.…”

Section: Resultsmentioning

confidence: 99%

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Piezotransistive transduction of femtoscale displacement for photoacoustic spectroscopy

et al. 2015

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Measurement of femtoscale displacements in the ultrasonic frequency range is attractive for advanced material characterization and sensing, yet major challenges remain in their reliable transduction using non-optical modalities, which can dramatically reduce the size and complexity of the transducer assembly. Here we demonstrate femtoscale displacement transduction using an AlGaN/GaN heterojunction field effect transistor-integrated GaN microcantilever that utilizes piezoelectric polarization-induced changes in two-dimensional electron gas to transduce displacement with very high sensitivity. The piezotransistor demonstrated an ultra-high gauge factor of 8,700 while consuming an extremely low power of 1.36 nW, and transduced external excitation with a superior noise-limited resolution of 12.43 fm Hz−1/2 and an outstanding responsivity of 170 nV fm−1, which is comparable to the optical transduction limits. These extraordinary characteristics, which enabled unique detection of nanogram quantity of analytes using photoacoustic spectroscopy, can be readily exploited in realizing a multitude of novel sensing paradigms.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Piezotransistive transduction of femtoscale displacement for photoacoustic spectroscopy

et al. 2015

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“…3 Measurement results and discussion Hall measurements show an increase of the sheet carrier density n SHEET with increasing doping level from 7x10 12 to 9.7x10 12 cm -2 , while the Hall mobility µ HALL is reduced from 1930 down to 1670 cm 2 /Vs, as shown in Table 1. In a former work we have evaluated the mobility of the 2DEG by channel conductivity measurements on FATFET structures [4]. We observed that the mobility only depends on the actual sheet carrier concentration and is not influenced by the existence of a carrier supply layer.…”

Section: Introductionmentioning

confidence: 96%

“…The local mobility in Fig. 1 is defined as the mobility of the carriers that are added into the channel with gate voltage increase [4]. Obviously all three samples show the same dependence of the mobility on the 2DEG sheet concentration.…”

Section: Introductionmentioning

confidence: 99%

Influence of carrier supply doping on the RF properties of AlGaN/GaN/SiC high‐electron‐mobility transistors

Marso¹,

Bernát²,

Javorka³

et al. 2005

phys. stat. sol. (c)

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We have fabricated undoped as well as modulation-doped AlGaN/GaN HEMTs on SiC substrate. The influence of the carrier supply layer on device performance is investigated by Hall, channel conductivity, small signal RF and delay time evaluation. While the doping layer improves the DC performance it degrades the RF behaviour of the device with the highest carrier supply doping of 5x10 18 cm -3. The channel conductivity measurements show identical dependence of the mobility on carrier concentration for all samples. The saturation velocity, extracted by evaluation of the total delay time as function of the inverse drain current, decreases from 0.86x10 7 cm/s for the undoped device to 0.7x10 7 cm/s for the highest doped HEMT. This result shows that the degradation of RF performance is due to the reduction of the effective saturation velocity caused by the carrier supply layer.

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“…Schottky barrier height 1.3 + 0.84 eV can be as high as 5 V. When the applied gate voltage is high, the conduction band near the AlGaN barrier layer will drop below the Fermi level which will significantly increase the carrier concentration of the AlGaN barrier layer. This phenomenon is also known as carrier spill-over and is reported in experimental work on the measurement of drift mobility and gate charge on AlGaN/GaN devices[83],[84].In order to model the carrier concentration of the AlGaN barrier layer, nb, the effective electric field in the AlGaN layer is used in a simplified Fermi-Dirac statistic by considering EF > ΔEC[85].The effective 2DEG carrier concentration at any point can be then modified from (4.1) as,…”

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confidence: 70%

Modeling of gallium nitride transistors for high power and high temperature applications

Shamsir¹

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Wide bandgap (WBG) semiconductors such as GaN and SiC are emerging as promising alternatives to Si for new generation of high efficiency power devices. GaN has attracted a lot of attention recently because of its superior material properties leading to potential realization of power transistors for high power, high frequency, and high temperature applications. In order to utilize the full potential of GaN-based power transistors, proper device modeling is essential to verify its operation and improve the design efficiency. In this view, this research work presents modeling and characterization of GaN transistors for high power and high temperature applications. The objective of this research work includes three key areas of GaN device modeling such as physics-based analytical modeling, device simulation with numerical simulator and electrothermal SPICE model for circuit simulation. The analytical model presented in this dissertation enables understanding of the fundamental physics of this newly emerged GaN device technology to improve the operation of existing device structures and to optimize the device configuration in the future. The numerical device simulation allows to verify the analytical model and study the impact of different device parameters. An empirical SPICE model for standard circuit simulator has been developed and presented in the dissertation which allows simulation of power electronic circuits employing GaN power devices. The empirical model provides a good approximation of the device behavior and creates a link between the physics-based analytical model and the actual device testing data. Furthermore, it includes an electrothermal model which can predict the device behavior at elevated temperatures as required for high temperature applications.

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Influence of a carrier supply layer on carrier density and drift mobility of AlGaN/GaN/SiC high-electron-mobility transistors

Cited by 21 publications

References 11 publications

Piezotransistive transduction of femtoscale displacement for photoacoustic spectroscopy

Piezotransistive transduction of femtoscale displacement for photoacoustic spectroscopy

Influence of carrier supply doping on the RF properties of AlGaN/GaN/SiC high‐electron‐mobility transistors

Modeling of gallium nitride transistors for high power and high temperature applications

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