AlGaN/GaN HEMTs on SiC with f/sub T/ of over 120 GHz

Kumar, V.; Lu, Wu; Schwindt, R.; Kuliev, A.; Simin, Grigory; Yang, J.; Khan, M. Asif; Adesida, I.

doi:10.1109/led.2002.801303

Cited by 211 publications

(87 citation statements)

References 11 publications

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“…Therefore, GaN and some other compounds have been studied extensively for their applications in short wavelength optical and high-power/temperature devices, such as light emitting diodes (LEDs), laser diodes (LDs), metal-semiconductor (MS) Schottky barrier diodes (SBDs), metal-insulator-semiconductor high-electron-mobility transistors (MISHEMTs). GaN high-electron-mobility transistors (HEMTs) with Schottky/rectifier metal contact have demonstrated excellent highfrequency, high-power, high temperature and recently good microwave-noise characteristics [1][2][3][4][5][6][7][8][9][10]. The performance level of GaN/ AlGaN HEMT devices has increased rapidly over the last few years.…”

Section: Introductionmentioning

confidence: 99%

On the profile of frequency dependent dielectric properties of (Ni/Au)/GaN/Al0.3Ga0.7N heterostructures

Tekeli

Gökçen

Altındal

et al. 2011

Microelectronics Reliability

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a b s t r a c tThe voltage (V) and frequency (f) dependence of dielectric characteristics such as dielectric constant (e 0 ), dielectric loss (e 00 ), dielectric loss tangent (tan d) and real and imaginary part of electrical modulus (V 0 and M 00 ) of the (Ni/Au)/GaN/Al 0.3 Ga 0.7 N heterostructures have been investigated by using experimental admittance spectroscopy (capacitance-voltage (C-V) and conductance-voltage (G/w-V)) measurements at room temperature. Experimental results show that the values of the e 0 , e 00 , tan d and the real and imaginary parts of the electric modulus (V 0 and M 00 ) obtained from the C and G/w measurements were found to be strong function of frequency and applied bias voltage especially in depletion region at low frequencies. These changes in dielectric parameters can be attributed to the interfacial GaN cap layer, interface polarization and a continuous density distribution of interface states and their relaxation time at metal/semiconductor interface. While the values of the e 0 decrease with increasing frequencies, tan d, V 0 and M 00 increase with the increasing frequency. Also, the dielectric loss (e 00 ) have a local maximum at about frequency of 100 kHz. It can be concluded that the interface polarization can occur more easily at low frequencies with the number of interface states located at the metal/semiconductor interface.

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Section: Introductionmentioning

confidence: 99%

On the profile of frequency dependent dielectric properties of (Ni/Au)/GaN/Al0.3Ga0.7N heterostructures

Tekeli

Gökçen

Altındal

et al. 2011

Microelectronics Reliability

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“…Results show that AlGaN/GaN interface trap states are responsible for the trapping behavior in the 10 kHz -1 MHz frequency range. An increase of AlGaN layer thickness or Al composition leads to greater trap state density at the AlGaN/GaN interface.1 Introduction The large conduction band discontinuity and high density two-dimensional electron gas (2DEG) in the AlGaN/GaN interface make AlGaN/GaN heterostructure field-effect transistors a promising candidate in high-power microwave amplifier applications [1,2]. However, the development of AlGaN/GaN heterostructure field-effect transistors (HFETs) is still largely hindered by the limiting effect of the trap states in AlGaN/GaN heterostructures [3].…”

mentioning

confidence: 99%

Admittance characterization and analysis of trap states in AlGaN/GaN heterostructures

Chu

Zhou

Chen

et al. 2003

phys. stat. sol. (c)

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We present a systematic study on the admittance characterization of trap states in AlGaN/GaN heterostructures. An equivalent circuit model was developed to analyze the spatial location, energy distribution density, and time constant of the AlGaN/GaN trap states. Results show that AlGaN/GaN interface trap states are responsible for the trapping behavior in the 10 kHz -1 MHz frequency range. An increase of AlGaN layer thickness or Al composition leads to greater trap state density at the AlGaN/GaN interface.1 Introduction The large conduction band discontinuity and high density two-dimensional electron gas (2DEG) in the AlGaN/GaN interface make AlGaN/GaN heterostructure field-effect transistors a promising candidate in high-power microwave amplifier applications [1,2]. However, the development of AlGaN/GaN heterostructure field-effect transistors (HFETs) is still largely hindered by the limiting effect of the trap states in AlGaN/GaN heterostructures [3]. These trap states may be located at the AlGaN surface, in the AlGaN barrier layer, at the AlGaN/GaN heterointerface, or in the GaN buffer layer. The presence of trap states in AlGaN/GaN HFETs can cause a voltage delay in device operation through trapping and de-trapping process, thereby degrading the power handling capability at high frequency. In this paper, we provide a qualitative and quantitative evaluation on the electronic properties of trap states. Bias voltage-and frequency-dependent admittance measurements were performed on AlGaN/GaN heterostructures. A frequency dispersion of the admittance was observed, and analyzed by deploying an equivalent circuit model.

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“…The maximum I ds was about 0.93 A/mm under V gs = 0 V. We obtained f T of 107 GHz at L g = 35 nm under V ds = 3 V and V gs = -3.6 V. Figure 5 shows the frequency dependence of the current gain of the 35-nm-gate HEMT with L sd = 1.5 µm under V ds = 4 V and V gs = -3.7 V. An f T of 110 GHz was obtained by extrapolating the current gain. The record f T for AlGaN/GaN HEMTs is currently 121 GHz [11]. That HEMT had L g = 120 nm and part of the AlGaN barrier layer was Si-doped.…”

Section: Resultsmentioning

confidence: 99%

Fabrication of sub‐50‐nm‐gate i‐AlGaN/GaN HEMTs on sapphire

Endoh

Yamashita

Ikeda

et al. 2003

phys. stat. sol. (c)

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We fabricated sub-50-nm-gate i-AlGaN/GaN high electron mobility transistors (HEMTs) on sapphire and measured their DC and RF characteristics at room temperature. The fabricated HEMTs exhibited true device operation and good pinch-off characteristics down to a gate length L g of 25 nm. For the HEMTs with a source-drain spacing L sd of 2 µm, we obtained the L g dependence of the cutoff frequency f T under a drain-source voltage V ds of 3 V. The peak f T was measured to be 102 GHz at L g = 35 nm. At L g = 25 nm, f T started to decrease due to the short-channel effect. The highest f T of 110 GHz was obtained by reducing L sd from 2 to 1.5 µm and by increasing V ds from 3 to 4 V. . However, obtaining the electron peak velocity requires a much higher electric field for GaN (~140 kV/cm) than for In 0.53 Ga 0.47 As (~4 kV/cm). Reducing gate length L g is a straightforward method of obtaining a very high electric field, similar to applying a high voltage. For AlGaN/GaN HEMTs, the shortest reported L g is 50 nm [3]. We previously developed a fabrication technique for sub-50-nm-gate HEMTs for the InAlAs/InGaAs material system using electron beam (EB) lithography [4].In the present work, we used this technique to fabricate sub-50-nm-gate i-AlGaN/GaN HEMTs on sapphire and successfully tested true device operation.

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AlGaN/GaN HEMTs on SiC with f/sub T/ of over 120 GHz

Cited by 211 publications

References 11 publications

On the profile of frequency dependent dielectric properties of (Ni/Au)/GaN/Al0.3Ga0.7N heterostructures

On the profile of frequency dependent dielectric properties of (Ni/Au)/GaN/Al0.3Ga0.7N heterostructures

Admittance characterization and analysis of trap states in AlGaN/GaN heterostructures

Fabrication of sub‐50‐nm‐gate i‐AlGaN/GaN HEMTs on sapphire

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