High electron concentrations in Si-doped AlN/AlGaN superlattices with high average Al content of 80%

2003 ◽  
Vol 200 (1) ◽  
pp. 40-43 ◽  
Author(s):  
Yoshitaka Taniyasu ◽  
Makoto Kasu ◽  
Kazuhide Kumakura ◽  
Toshiki Makimoto ◽  
Naoki Kobayashi
Keyword(s):  
High Electron ◽  
Al Content ◽  
Si Doped

scholarly journals Theoretical Study of InAlN/GaN High Electron Mobility Transistor (HEMT) with a Polarization-Graded AlGaN Back-Barrier Layer

Electronics ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 885 ◽  
Author(s):  
Yan Gu ◽  
Dongmei Chang ◽  
Haiyan Sun ◽  
Jicong Zhao ◽  
Guofeng Yang ◽  
...  
Keyword(s):  
Electron Mobility ◽  
Theoretical Study ◽  
Lattice Relaxation ◽  
High Electron Mobility Transistor ◽  
High Electron ◽  
Two Dimensional ◽  
Drift Diffusion ◽  
High Electron Mobility ◽  
Al Content ◽  
Dimensional Electron Gas

An inserted novel polarization-graded AlGaN back barrier structure is designed to enhance performances of In0.17Al0.83N/GaN high electron mobility transistor (HEMT), which is investigated by the two-dimensional drift-diffusion simulations. The results indicate that carrier confinement of the graded AlGaN back-barrier HEMT is significantly improved due to the conduction band discontinuity of about 0.46 eV at interface of GaN/AlGaN heterojunction. Meanwhile, the two-dimensional electron gas (2DEG) concentration of parasitic electron channel can be reduced by a gradient Al composition that leads to the complete lattice relaxation without piezoelectric polarization, which is compared with the conventional Al0.1Ga0.9N back-barrier HEMT. Furthermore, compared to the conventional back-barrier HEMT with a fixed Al-content, a higher transconductance, a higher current and a better radio-frequency performance can be created by a graded AlGaN back barrier.

High electron mobility in AlGaN/GaN HEMT grown on sapphire: strain modification by means of AlN interlayers.

2003 ◽  
Vol 798 ◽  
Author(s):  
Marianne Germain ◽  
Maarten Leys ◽  
Steven Boeykens ◽  
Stefan Degroote ◽  
Wenfei Wang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Sheet Resistance ◽  
Electron Mobility ◽  
Record Values ◽  
Strain Engineering ◽  
Threading Dislocation ◽  
High Electron ◽  
Nucleation Layer ◽  
High Electron Mobility ◽  
Al Content

ABSTRACTThe performance of AlGaN/GaN High Electron Mobility (HEMT) transistors is directly related to the electrical characteristics of the two-dimensional electron gas formed at the interface thanks to the piezoelectric field. Modification of the Al content or thickness of the AlGaN layer can within a certain limit modify the carrier density and mobility in the 2DEG. However, further reduction of the sheet resistance requires strain engineering of the heterostructure. An effective way to reduce the sheet resistance, as well as to lower the threading dislocation (TD) density, is to perform strain engineering through the use of low temperature AlN interlayers inserted in the GaN buffer layer. From correlation of AFM, TEM and HRXRD mapping of the HEMT layers, the strain modification, as well as the mechanism reducing the TD density, can be explained by the highly defected nature of the AlN interlayer grown at low temperature, as well as its very small thickness. The LT AlN acts as a second nucleation layer for the GaN grown on top. Contrarily, when the AlN interlayer is grown at 1050°C, its high crystalline quality and the possibility to grow pseudomorphic and abrupt interfaces, allows its use at the AlGaN/GaN interface. Optimal combination of the AlGaN and AlN layer thickness leads to record values of the mobility at room temperature of 2050 cm2/Vs, for heterostructures grown on sapphire, which is approaching state-of-the-art for HEMT grown on SiC.

Influence of Al content on electrical and structural properties of Si-doped AlxGa1–xN/GaN HEMT structures

2006 ◽  
Vol 3 (3) ◽  
pp. 486-489 ◽  
Author(s):  
Cuimei Wang ◽  
Xiaoliang Wang ◽  
Guoxin Hu ◽  
Junxi Wang ◽  
Jianping Li
Keyword(s):  
Structural Properties ◽  
Al Content ◽  
Gan Hemt ◽  
Si Doped

AlGaN/GaN Based HEMTs on SiC/Si-Substrates: Influences on High Frequency Performance

2013 ◽  
Vol 740-742 ◽  
pp. 1115-1118 ◽  
Author(s):  
Wael Jatal ◽  
Katja Tonisch ◽  
Uwe Baumann ◽  
Frank Schwierz ◽  
Jörg Pezoldt
Keyword(s):  
Chemical Vapour Deposition ◽  
Transition Layer ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Drain Current ◽  
Current Gain ◽  
Organic Chemical ◽  
High Electron ◽  
Al Content ◽  
Si Substrates

Al0.35Ga0.65N/GaN- and Al0.2Ga0.8N/AlN/GaN-heterostructures high electron mobility transistors (HEMTs) with a gate length (LG) varying from 1.2 to 0.08 µm were fabricated on silicon Si(111) substrates using a 3C-SiC transition layer. Metal organic chemical vapour deposition (MOCVD) was used to growth the AlGaN-heterostructures and a low pressure chemical vapour deposition (LPCVD) to create the 3C-SiC(111) transition layer preventing Ga-induced melt back etching and Si-out diffusion. Reduced Al content and an AlN interlayer improved the device performance. The HEMTs with LG=0.08µm had a maximum drain current density of 1.25 A/mm and a peak extrinsic transconductance of 400 mS/mm. A unity current gain cut-off frequency (ƒT) of 180 GHz and maximum frequency (ƒmax) of 70 GHz were measured on these devices.

scholarly journals Investigation of Recessed Gate AlGaN/GaN MIS-HEMTs with Double AlGaN Barrier Designs toward an Enhancement-Mode Characteristic

Micromachines ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 163 ◽  
Author(s):  
Tian-Li Wu ◽  
Shun-Wei Tang ◽  
Hong-Jia Jiang
Keyword(s):  
Gate Dielectric ◽  
High Electron Mobility Transistors ◽  
High Electron ◽  
Al Content ◽  
Enhancement Mode ◽  
Electron Mobility Transistors ◽  
Algan Barrier ◽  
Mode Characteristic ◽  
Recessed Gate ◽  
Gate Region

In this work, recessed gate AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) with double AlGaN barrier designs are fabricated and investigated. Two different recessed depths are designed, leading to a 5 nm and a 3 nm remaining bottom AlGaN barrier under the gate region, and two different Al% (15% and 20%) in the bottom AlGaN barriers are designed. First of all, a double hump trans-conductance (gm)–gate voltage (VG) characteristic is observed in a recessed gate AlGaN/GaN MIS-HEMT with a 5 nm remaining bottom Al0.2Ga0.8N barrier under the gate region. Secondly, a physical model is proposed to explain this double channel characteristic by means of a formation of a top channel below the gate dielectric under a positive VG. Finally, the impacts of Al% content (15% and 20%) in the bottom AlGaN barrier and 5 nm/3 nm remaining bottom AlGaN barriers under the gate region are studied in detail, indicating that lowering Al% content in the bottom can increase the threshold voltage (VTH) toward an enhancement-mode characteristic.

The Effect of Substrate Orientation on the Properties of (Ga, Al)As Grown by Gas Source Molecular Beam Epitaxy

1988 ◽  
Vol 144 ◽  
Author(s):  
A. Sandhu ◽  
T. FUJII ◽  
H. Ando ◽  
H. Ishikawa ◽  
E. Miyauchi
Keyword(s):  
Growth Rate ◽  
Growth Conditions ◽  
Group V ◽  
Group Iii ◽  
Al Content ◽  
Gas Source ◽  
Compensation Ratio ◽  
Potential Applications ◽  
Si Doped ◽  
Gas Source Mbe

ABSTRACTWe have carried out the first systemmatic investigation on the effect of substrate temperature and arsenic partial pressure on the morphology, growth rate, and compensation ratio of Si-doped GaAs, and the Al content of AlxGa1−xAs grown on just-cut (100), (110), (111)A&B, (311)A&B orientated GaAs substrates by gas source MBE (GSMBE). Triethylgallium ( TEG, Ga(C2H5)3 ) and triethylaluminium ( TEA, Al(C2H5)3 ) were used as group III sources, and solid arsenic ( As4 ) and silicon as a group V and IV sources, respectively. The best GaAs mophology was obtained at relatively high temperatures and arsenic pressures. The A orientations were identified as ‘fast surfaces,’ with the GaAs growth rate being comparable to the (100) orientation. The B orientations were identified as ‘slow surfaces,’ with the GaAs growth rate being much less (approximately 50% for the (111)B orientation ) than on the (100) orientation. The least compensated Si-doped GaAs was grown on the (311)A orientated substrate. The Al content, x, (nominally x=0.27 for (100)) of AlxGas1−xAs grown on (110), (111)A&B, was less than 0.05 and not affected by the growth conditions. The Al content of epilayers grown on (311)A&B ranged between x=0.1 to 0.27, strongly depending on the growth temperature.These results show that using GSMBE we can selectively modifying a large range of (Ga,Al)As crystal properties. Potential applications include the selective growth and realisation of ultra-fine and planar structures and devices.

scholarly journals Structural Features and Photoelectric Properties of Si-Doped GaAs under Gamma Irradiation

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 340 ◽  
Author(s):  
Ye Shen ◽  
Xuan Fang ◽  
Xiang Ding ◽  
Haiyan Xiao ◽  
Xia Xiang ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Gamma Irradiation ◽  
Wide Band ◽  
Structural Features ◽  
High Electron ◽  
Nonradiative Recombination ◽  
Photoluminescence Intensity ◽  
Light Emitting Devices ◽  
Photoelectric Properties ◽  
Si Doped

GaAs has been demonstrated to be a promising material for manufacturing semiconductor light-emitting devices and integrated circuits. It has been widely used in the field of aerospace, due to its high electron mobility and wide band gap. In this study, the structural and photoelectric characteristics of Si-doped GaAs under different gamma irradiation doses (0, 0.1, 1 and 10 KGy) are investigated. Surface morphology studies show roughen of the surface with irradiation. Appearance of transverse-optical (TO) phonon mode and blueshift of TO peak reflect the presence of internal strain with irradiation. The average strain has been measured to be 0.009 by Raman spectroscopy, indicating that the irradiated zone still has a good crystallinity even at a dose of 10 KGy. Photoluminescence intensity is increased by about 60% under 10 KGy gamma irradiation due to the strain suppression of nonradiative recombination centers. Furthermore, the current of Si-doped GaAs is reduced at 3V bias with the increasing gamma dose. This study demonstrates that the Si-doped GaAs has good radiation resistance under gamma irradiation, and appropriate level of gamma irradiation can be used to enhance the luminescence property of Si-doped GaAs.

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