Novel Selective Area Recessed Regrowth-free Ohmic Contacts to High Al-content Barrier

ABSTRACTOhmic contacts and Schottky contacts were made on an undoped AlGaN/GaN FET structure. Despite the high Al content (33%), we were still able to obtain a contact resistance of 0.3 ωmm. Pulsed measurements showed the large effect of self-heating even for circular contacts with a radius of 50 μm. The behavior ofthe Ni/Au Schottky contacts is according to the charge control model; the reverse current and capacitanceonly scale with the area of the diode. Tests with polygon type diodes showed no dependence of the reverse current on the number of polygon corners. The reverse current decreased when the devices were aged at 400°C for 30 hrs. Coplanar Waveguide discontinuities were realized on AlN substrates. A scalable lumped element model was derived from measurements for T-junctions, transmission lines, bends and crosses.

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Selective Area Deposition of Passivants, Insulators, and Epitaxial Films of II-VI Compound Semiconductors

MRS Proceedings ◽

10.1557/proc-161-159 ◽

1989 ◽

Vol 161 ◽

Author(s):

D.L. Dreifus ◽

Y. Lansari ◽

J.W. Han ◽

S. Hwang ◽

J.W. Cook ◽

...

Keyword(s):

Ohmic Contacts ◽

Epitaxial Films ◽

Semiconductor Surface ◽

Epitaxial Layers ◽

Double Crystal ◽

Surface Areas ◽

Selective Area ◽

Lift Off ◽

P Type ◽

Area Deposition

ABSTRACTII-VI semiconductor surface passivants, insulators, and epitaxial films have been deposited onto selective surface areas by employing a new masking and lift-off technique. The II-VI layers were grown by either conventional or photoassisted molecular beam epitaxy (MBE). CdTe has been selectively deposited onto HgCdTe epitaxial layers as a surface passivant. Selective-area deposition of ZnS has been used in metal-insulator-semiconductor (MIS) structures. Low resistance ohmic contacts to p-type CdTe:As have also been realized through the use of selectively-placed thin films of the semi-metal HgTe followed by a thermal evaporation of In. Epitaxial layers of HgTe, HgCdTe, and HgTe-CdTe superlattices have also been grown in selective areas on CdZnTe substrates, exhibiting specular morphologies and double-crystal x-ray diffraction rocking curves (DCXD) with full widths at half maximum (FWHMs) as narrow as 140 arcseconds.

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Dielectric properties of anodized Al-Ta alloy films with high Al content

Thin Solid Films ◽

10.1016/0040-6090(75)90012-7 ◽

1975 ◽

Vol 27 (1) ◽

pp. 111-121 ◽

Cited By ~ 5

Author(s):

A. Schauer ◽

M. Roschy ◽

W. Juergens

Keyword(s):

Dielectric Properties ◽

Alloy Films ◽

Al Content ◽

High Al Content

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High Al-content AlGaN/GaN HEMTs on SiC substrates with very high power performance

International Electron Devices Meeting 1999. Technical Digest (Cat. No.99CH36318) ◽

10.1109/iedm.1999.824300 ◽

2003 ◽

Cited By ~ 38

Author(s):

Y.-F. Wu ◽

D. Kapolnek ◽

J. Ibbetson ◽

N.-Q. Zhang ◽

P. Parikh ◽

...

Keyword(s):

High Power ◽

Power Performance ◽

Al Content ◽

Gan Hemts ◽

High Al Content ◽

Very High

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Lake sedimentary biogenic silica from diatoms constitutes a significant global sink for aluminium

Nature Communications ◽

10.1038/s41467-019-12828-9 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 2

Author(s):

Dong Liu ◽

Peng Yuan ◽

Qian Tian ◽

Hongchang Liu ◽

Liangliang Deng ◽

...

Keyword(s):

Biogenic Silica ◽

Biogeochemical Cycle ◽

Biochemical Processes ◽

Al Content ◽

High Al Content ◽

Global Oceans

Abstract Diatoms play an important role in marine biogeochemical cycle of aluminum (Al), as dissolved Al is taken up by diatoms to build their siliceous frustules and is involved in the sedimentation of diatomaceous biogenic silica (BSi). The Al incorporation in BSi facilitates decreasing the dissolution of marine BSi and thus substantially influences the biochemical processes driven by diatoms, such as CO2 sequestration. However, the role of lake BSi in the terrestrial biochemical Al cycle has not been explored, though lakes represent the second-largest sink for BSi. By identifying the previously unexplored high Al/Si atomic ratios (up to 0.052) in lake BSi, here we show lake BSi is a large terrestrial Al pool due to its high Al content, and lake sedimentary BSi constitutes a significant global sink for Al, which is on the same magnitude as the Al sink in global oceans.

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Theory of Defects, Doping, Surfaces and Interfaces in Wide Gap Nitrides

MRS Proceedings ◽

10.1557/proc-423-465 ◽

1996 ◽

Vol 423 ◽

Cited By ~ 1

Author(s):

J. Bernholc ◽

P. Boguslawski ◽

E. L. Briggs ◽

M. Buongiorno Nardelli ◽

B. Chen ◽

...

Keyword(s):

Nearest Neighbor ◽

Group Iv ◽

Type I ◽

Shallow Acceptor ◽

Surface And Interface ◽

Al Content ◽

Surfaces And Interfaces ◽

High Concentrations ◽

P Type ◽

High Al Content

AbstractThe results of extensive theoretical studies of group IV impurities and surface and interface properties of nitrides are presented and compared with available experimental data. Among the impurities, we have considered substitutional C, Si, and Ge. CN is a very shallow acceptor, and thus a promising p-type dopant. Both Si and Ge are excellent donors in GaN. However, in AlGaN alloys the DX configurations are stable for a sufficiently high Al content, which quenches the doping efficiency. At high concentrations, it is energetically favorable for group IV impurities to form nearest-neighbor Xcation-XN pairs. Turning to surfaces, AIN is known to exhibit NEA. We find that the NEA property depends sensitively on surface reconstruction and termination. At interfaces, the strain effects on the band offsets range from 20% to 40%, depending on the substrate. The AIN/GaN/InN interfaces are all of type I, while the A10.5Ga0.5 N/A1N zinc-blende (001) interface may be of type II. Further, the calculated bulk polarizations in wurtzite AIN and GaN are -1.2 and -0.45 μC/cm2, respectively, and the interface contribution to the polarization in the GaN/AlN wurtzite multi-quantum-well is small.

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