electron mobility transistors
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Electronics ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 259
Author(s):  
Bo Wang ◽  
Yanfu Wang ◽  
Ruize Feng ◽  
Haomiao Wei ◽  
Shurui Cao ◽  
...  

In this paper, we have fabricated InGaAs high-electron-mobility transistors (HEMTs) on Si substrates. The InAlAs/InGaAs heterostructures were initially grown on InP substrates by molecular beam epitaxy (MBE), and the adhesive wafer bonding technique was employed to bond the InP substrates to Si substrates, thereby forming high-quality InGaAs channel on Si. The 120 nm gate length device shows a maximum drain current (ID,max) of 569 mA/mm, and the maximum extrinsic transconductance (gm,max) of 1112 mS/mm. The current gain cutoff frequency (fT) is as high as 273 GHz and the maximum oscillation frequency (fMAX) reaches 290 GHz. To the best of our knowledge, the gm,max and the fT of our device are the highest ever reported in InGaAs channel HEMTs on Si substrates at given gate length above 100 nm.


Electronics ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 225
Author(s):  
A. Revathy ◽  
C. S. Boopathi ◽  
Osamah Ibrahim Khalaf ◽  
Carlos Andrés Tavera Romero

The wider bandgap AlGaN (Eg > 3.4 eV) channel-based high electron mobility transistors (HEMTs) are more effective for high voltage operation. High critical electric field and high saturation velocity are the major advantages of AlGaN channel HEMTs, which push the power electronics to a greater operating regime. In this article, we present the DC characteristics of 0.8 µm gate length (LG) and 1 µm gate-drain distance (LGD) AlGaN channel-based high electron mobility transistors (HEMTs) on ultra-wide bandgap β-Ga2O3 Substrate. The β-Ga2O3 substrate is cost-effective, available in large wafer size and has low lattice mismatch (0 to 2.4%) with AlGaN alloys compared to conventional SiC and Si substrates. A physics-based numerical simulation was performed to investigate the DC characteristics of the HEMTs. The proposed HEMT exhibits sheet charge density (ns) of 1.05 × 1013 cm−2, a peak on-state drain current (IDS) of 1.35 A/mm, DC transconductance (gm) of 277 mS/mm. The ultra-wide bandgap AlGaN channel HEMT on β-Ga2O3 substrate with conventional rectangular gate structure showed 244 V off-state breakdown voltage (VBR) and field plate gate device showed 350 V. The AlGaN channel HEMTs on β-Ga2O3 substrate showed an excellent performance in ION/IOFF and VBR. The high performance of the proposed HEMTs on β-Ga2O3 substrate is suitable for future portable power converters, automotive, and avionics applications.


2022 ◽  
Author(s):  
Xinchuang Zhang ◽  
Mei Wu ◽  
Bin Hou ◽  
Xuerui Niu ◽  
Hao Lu ◽  
...  

Abstract In this work, the N2O radicals in-situ treatment on gate region has been employed to improve device performance of recessed-gate AlGaN/GaN high-electron-mobility transistors (HEMTs). The samples after gate recess etching were treated by N2O radicals without physical bombardment. After in-situ treatment (IST) processing, the gate leakage currents decreased by more than one order of magnitude compared to the sample without IST. The fabricated HEMTs with the IST process show a low reverse gate current of 10-9 A/mm, high on/off current ratio of 108, and high fT×Lg of 13.44 GHz·μm. A transmission electron microscope (TEM) imaging illustrates an oxide layer with a thickness of 1.8 nm exists at the AlGaN surface. X-ray photoelectron spectroscopy (XPS) measurement shows that the content of the Al-O and Ga-O bonds elevated after IST, indicating that the Al-N and Ga-N bonds on the AlGaN surface were broken and meanwhile the Al-O and Ga-O bonds formed. The oxide formed by a chemical reaction between radicals and the surface of the AlGaN barrier layer is responsible for improved device characteristics.


Micromachines ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 84
Author(s):  
Surajit Chakraborty ◽  
Tae-Woo Kim

The reliability instability of inhomogeneous Schottky contact behaviors of Ni/Au and Pt/Ti/Pt/Au gate contacts on AlGaN/GaN high-electron-mobility transistors (HEMTs) was investigated via off-state stress and temperature. Under the off-state stress condition, Pt/Ti/Pt/Au HEMT showed abruptly reduced reverse leakage current, which improved the Schottky barrier height (SBH) from 0.46 to 0.69 eV by suppression of the interfacial donor state. As the temperature increased, the reverse leakage current of the Pt/Ti/Pt/Au AlGaN/GaN HEMT at 308 K showed more reduction under the same off-state stress condition while that of the Ni/Au AlGaN/GaN HEMT increased. However, with temperatures exceeding 308 K under the same off-state stress conditions, the reverse leakage current of the Pt/Ti/Pt/Au AlGaN/GaN HEMT increases, which can be intensified using the inverse piezoelectric effect. Based on this phenomenon, the present work reveals the necessity for analyzing the concurrent SBH and reliability instability due to the interfacial trap states of the MS contacts.


2021 ◽  
Author(s):  
Qiu-Ling Qiu ◽  
Shi-Xu Yang ◽  
Qian-Shu Wu ◽  
Cheng-Lang Li ◽  
Qi Zhang ◽  
...  

Abstract The strong polarization effect of GaN-based materials is widely used in high-performance devices such as white-light-emitting diodes (white LEDs), high electron mobility transistors (HEMTs) and GaN Polarization SuperJunctions. However, the current researches on the polarization mechanism of GaN-based materials are not sufficient. In this paper, we studied the influence of polarization on electric field and energy band characteristics of Ga-face GaN bulk materials by using a combination of theoretical analysis and semiconductor technology computer-aided design (TCAD) simulation. The self-screening effect in Ga-face bulk GaN under ideal and non-ideal conditions is studied respectively. We believe that the formation of high-density two-dimensional electron gas (2DEG) in GaN is the accumulation of screening charges. So that, we also clarify the source and accumulation of the screening charges caused by the GaN self-screening effect in this paper and aim to guide the design and optimization of high-performance GaN-based devices.


2021 ◽  
Author(s):  
Peng Cui ◽  
Yuping Zeng

Abstract Electron mobility is important for electron velocity, transport current, output power, and frequency characteristics. In conventional mobility extraction methods, electron mobility is usually extracted directly from the measured gate capacitance (CG) and current-voltage characteristics. When device gate length (LG) scales to sub-100 nm, the determination of CG becomes more difficult not only for the measure equipment but also the enhanced effect from parasitic capacitance. Here in this paper, the CG extracted from high-frequency small-signal equipment circuit is used for the InAlN/GaN high electron mobility transistors (HEMTs). Electron mobility of the device with LG of 60-nm under VDS of 0.1 V and 10 V is extracted using two-dimensional scattering theory, respectively. The obtained results show that under a high electric field, the electron temperature (Te) and addition polarization charges (∆σ) increase, resulting in the enhanced polar optical phonon (POP) as well as polarization Coulomb field (PCF) scatterings and degradation of the electron mobility. This study makes it possible to improve the electron mobility by reducing Te and ∆σ for the InAlN/GaN HEMTs application.AlGaN/GaN heterostructure field-effect transistors with different gate lengths were fabricated. Based on the chosen of the Hamiltonian of the system and the additional polarization charges, two methods to calculate PCF scattering by the scattering theory were presented. By comparing the measured and calculated source-drain resistances, the influence of the different gate lengths on the PCF scattering potential was confirmed.


Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 42
Author(s):  
Hsin-Ying Lee ◽  
Ying-Hao Ju ◽  
Jen-Inn Chyi ◽  
Ching-Ting Lee

In this work, Al0.83In0.17N/GaN/Al0.18Ga0.82N/GaN epitaxial layers used for the fabrication of double-channel metal–oxide–semiconductor high-electron mobility transistors (MOSHEMTs) were grown on silicon substrates using a metalorganic chemical vapor deposition system (MOCVD). A sheet electron density of 1.11 × 1013 cm−2 and an electron mobility of 1770 cm2/V-s were obtained. Using a vapor cooling condensation system to deposit high insulating 30-nm-thick Ga2O3 film as a gate oxide layer, double-hump transconductance behaviors with associated double-hump maximum extrinsic transconductances (gmmax) of 89.8 and 100.1 mS/mm were obtained in the double-channel planar MOSHEMTs. However, the double-channel devices with multiple-mesa-fin-channel array with a gmmax of 148.9 mS/mm exhibited single-hump transconductance behaviors owing to the better gate control capability. Moreover, the extrinsic unit gain cutoff frequency and maximum oscillation frequency of the devices with planar channel and multiple-mesa-fin-channel array were 5.7 GHz and 10.5 GHz, and 6.5 GHz and 12.6 GHz, respectively. Hooge’s coefficients of 7.50 × 10−5 and 6.25 × 10−6 were obtained for the devices with planar channel and multiple-mesa-fin-channel array operating at a frequency of 10 Hz, drain–source voltage of 1 V, and gate–source voltage of 5 V, respectively.


Author(s):  
Koichi Fukuda ◽  
Junichi Hattori ◽  
Hidehiro Asai ◽  
Mariko Ninomiya ◽  
Junya Yaita ◽  
...  

Abstract GaN-based high electron mobility transistors (HEMTs) are expected to have high performance in base station applications. Recently, it was reported that the combination of the Poisson-Schrodinger method and cellular automaton method is effective for predicting the mobility of channel two-dimensional electron gas (2DEG) of GaN HEMTs. In the operation condition of HEMT, the surface electron density of the channel is on the order of 1013 cm-2, and the effect of degeneracy cannot be ignored in calculating the mobility. Since the electron distribution function is always stably obtained by the cellular automaton method, the degeneracy effect can be considered stably. In this paper, through the comparison of different degeneracy evaluation methods, the anisotropy of the electron distribution function under the electric field acceleration is clarified to affect the HEMT mobility prediction significantly.


Electronics ◽  
2021 ◽  
Vol 10 (24) ◽  
pp. 3052
Author(s):  
Surajit Chakraborty ◽  
Tae-Woo Kim

We present the mean-time-to-failure (MTTF) calculations for AlGaN/GaN high-electron-mobility transistors (HEMTs) using two independent acceleration factors. MTTF predictions are generally calculated through the Arrhenius relationship, based on channel temperature and acceleration, depend only on one parameter. Although the failure modes of the AlGaN/GaN HEMTs depend largely on the applied electric fields, the Eyring model is introduced to investigate both voltage and temperature dependent degradation of AlGaN/GaN devices. In anticipation of adequate MTTF values, studies were conducted on non-commercial devices. Further, we distinguished the cumulative failure percentages through the Weibull and log-normal distributions. We also explored the increase in gate leakage current at high temperatures for early device deterioration.


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