Intrinsic noise equivalent-circuit parameters for AlGaN/GaN HEMTs (original) (raw)
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Excess low-frequency noise in AlGaN/GaN-based high-electron-mobility transistors
Applied Physics Letters, 2002
The low-frequency 1/f noise characteristics of AlGaN/GaN high-electron-mobility transistors with gate length scaled down to 150 nm grown on sapphire by metalorganic chemical vapor deposition have been studied. Certain features of the 1/f noise have been revealed in these short-gate transistors. The low-frequency noise spectra show drastically different behavior depending on the gate voltage V G in the range of low (V Gt рV G р0) and high (V G ϽV Gt) biases. The noise spectra-gate bias dependences allow one to distinguish a spatial redistribution of effective noise sources in the transistor channel. The Hooge parameter has been deduced separately for the ungated region, ␣ H p Ӎ10 Ϫ3 , and for the gated region, ␣ H a Ӎ2ϫ10 Ϫ4 , of the transistor channel. These values are as low as those previously observed in nitride heterostructures grown on silicon carbide substrates.
Influence of epitaxial structure in the noise figure of AlGaN/GaN HEMTs
IEEE Transactions on Microwave Theory and Techniques, 2000
The effect of noise figure of different AlGaN/GaN high electron-mobility transistor (HEMT) epitaxy structures is reported. The addition of a thin AlN layer between the barrier and channel gives better performance at biasings other than the best for minimum noise figure. However, varying Al composition in the HEMT barrier does not change the noise performance, contrary to a 2003 study by Lu et al. The measurements are checked with both the Pospieszalski and van der Ziel (Pucel) models. The models are used on six different samples, helping to reinforce the measurements and showing the strengths and weaknesses of each. Index Terms-AlGaN, GaN, high electron-mobility transistor (HEMT), noise figure, Pospieszalski, Pucel, van der Ziel.
Impact of AlGaN Barrier Thickness and Substrate Material on the Noise Characteristics of GaN HEMT
IEEE Journal of the Electron Devices Society
In this paper, the impact of AlGaN barrier thickness (t AlGaN) and substrate leakage on the noise conductance and noise figure in GaN High Electron Mobility Transistor (HEMT) is investigated. The investigation and analysis in this paper are targeting the Low Noise Amplifier (LNA) applications. The noise analysis is carried out using Technology Computer-Aided Design (TCAD) physical simulator. Initially, the DC, RF, and noise simulations are validated against measurements of a GaN device. AlGaN barrier thickness (t AlGaN) is varied and its impact on the minimum noise figure (NFmin) is analyzed. It is observed that the NFmin decreases with t AlGaN reduction at the typical bias conditions of LNA. This observation on the impact of t AlGaN on the NFmin follows Fukui's model, which states that the NFmin decreases with the increase in transconductance. In addition, the impact of the substrate material on noise performance is analyzed. The substrates used for the investigation are Silicon (Si) and Silicon Carbide (SiC). At 40 GHz, it is found that the noise conductance and the NFmin of GaN HEMT on SiC substrate is reduced by 13% and 12%, respectively, in comparison with GaN HEMT on Si substrate. This could be attributed to the lower gate-to-substrate capacitance of the GaN HEMT on SiC substrate. INDEX TERMS LNA, AlGaN barrier, substrate leakage, noise figure.
Microwave noise performance of AlGaN/GaN HEMTs
Electronics Letters, 2000
We report low microwave noise performance of discrete AlGaN-GaN HEMTs at dc power dissipation comparable to that of GaAs-based low-noise FETs. At 1-V source-drain (SD) bias and dc power dissipation of 97 mW/mm, minimum noise figures (NF min) of 0.75 dB at 10 GHz and 1.5 dB at 20 GHz were achieved, respectively. A device breakdown voltage of 40 V was observed. Both the low microwave noise performance at small dc power level and high breakdown voltage was obtained with a shorter SD spacing of 1.5 m in 0.15-m gate length GaN HEMTs. By comparison, NF min with 2 m SD spacing was 0.2 dB greater at 10 GHz.
Noise performance in AlGaN/GaN HEMTs under high drain bias
Journal of Semiconductors, 2009
The advent of fully integrated GaN PA-LNA circuits makes it meaningful to investigate the noise performance under high drain bias. However, noise performance of AlGaN/GaN HEMTs under high bias has not received worldwide attention in theoretical studies due to its complicated mechanisms. The noise value is moderately higher and its rate of increase is fast with increasing high voltage. In this paper, several possible mechanisms are proposed to be responsible for it. Impact ionization under high electric field incurs great fluctuation of carrier density, which increases the drain diffusion noise. Besides, higher gate leakage current related shot noise and a more severe selfheating effect are also contributors to the noise increase at high bias. Analysis from macroscopic and microscopic perspectives can help us to design new device structures to improve noise performance of AlGaN/GaN HEMTs under high bias.
Gate and drain low frequency noise of ALGAN/GAN HEMTs featuring high and low gate leakage currents
2013 22nd International Conference on Noise and Fluctuations (ICNF), 2013
The qualification of a technology needs rigorous and numerous stress experiments to attest of a high level of reliability. Low frequency noise measurements are known as an effective characterization method for the evaluation of device reliability. This technique is usually applied on the drain current spectral density, but it is now largely accepted that the gate access is a major reliability indicator. Moreover, devices featuring slight differences in their drain current noise can be subjected to strong differences on their gate leakage currents, and as a consequence on the current low frequency noise (LFN). In the present work, LFN measurements are investigated on the gate and drain currents of two sets of AlGaN/GaN high electron mobility transistors (HEMTs) with high and low gate leakage currents. It is demonstrated that devices featuring weak differences on their drain current can be subjected to strong differences on their gate leakage signatures: moreover, it is found that the high leakage current can generate numerous traps under the gated zone of the transistor, leading to a change of the intrinsic tuning voltage and by consequence of the number of carriers, thus explaining the reduction on the drain current. The transistors show a difference of 3 to 4 decades on their gate current noise and a negligible shift of 20% on their drain current noise. The large variations on the gate LFN signatures between the two sets of devices, and the induced charges for the leaky devices can probably be related with large differences on the expected lifetimes for the devices under test.
Noise characteristics of AlInN/GaN HEMTs at microwave frequencies
2013 22nd International Conference on Noise and Fluctuations (ICNF), 2013
Frequency dispersion of transconductance and output conductance in AlInN/GaN high electron mobility transistors is investigated in this paper. Broadband dispersion effects in the microwave frequency range are reported for the first time. A small-signal model is developed. Trapping effects are taken into account with parasitic electrical networks including distributed time constants. The model is compared to experimental data for several bias conditions and different types of dispersion.
Fluctuation and Noise Letters, 2001
The dependence of the 1/f noise on 2D electron concentration in the channel n Ch of AlGaN/GaN Heterostructure Field Effect Transistors and Metal Oxide Semiconductor Heterostructure Field Effect Transistors has been studied and compared. The dependencies of Hooge parameter α Ch for the noise sources located in the channel of the transistors on sheet electron concentration are found identical for both types of devices. The increase of the Hooge parameter α Ch with the decrease of the channel concentration observed in both types of devices confirms that the noise sources are located in the region under the gate in the AlGaN/GaN heterostructure and that electron tunneling from the 2D electron gas into the traps in GaN or AlGaN layers is a probable noise mechanism.
Low-frequency noise properties of double channel AlGaN/GaN HEMTs
Solid-State Electronics, 2008
Low-frequency noise in MOCVD-grown AlGaN/GaN/AlGaN/GaN double channel high electron mobility transistors (HEMTs) on sapphire substrate was investigated over a wide range of temperatures from 80 K to 300 K. Generation-recombination (g-r) noise was observed arising from the traps with activation energies 140 meV, 188 meV and 201 meV. Hooge parameter was estimated to be 1.6 · 10 À3 at room temperature. Our work demonstrates good dc and low-frequency noise properties for the device.
Effect of gate leakage current on noise properties of AlGaN/GaN field effect transistors
Journal of Applied Physics, 2000
The effect of the gate leakage current fluctuations on noise properties of AlGaN/GaN heterostructure field effect transistors ͑HFETs͒ has been studied in conventional HFET structures and in AlGaN/GaN metal-oxide-semiconductor heterostructure field effect transistors ͑MOS-HFETs͒. The comparison of the noise properties of conventional AlGaN/GaN HFETs and AlGaN/GaN MOS-HFETs fabricated on the same wafer, allowed us to estimate the contribution of the gate current noise to the HFET's output noise. The effect of the gate current fluctuations on output noise properties of HFETs depends on the level of noise in the AlGaN/GaN HFETs. For the transistors with a relatively high magnitude of the Hooge parameter ␣ϳ10 Ϫ3 , even a relatively large leakage current I g ͑I g /I d ϳ10 Ϫ3-10 Ϫ2 , where I d is the drain current͒ does not contribute much to the output noise. In HFETs with a relatively small values of ␣ (␣ϳ10 Ϫ5-10 Ϫ4), the contribution of the leakage current to output noise can be significant even at I g /I d ϳ10 Ϫ4-10 Ϫ3. For such transistors, a very rapid increase of the 1/f noise with gate bias was observed. The differences in the noise behavior can be linked to the material quality of the AlGaN and GaN layers in different types of HFETs.