scholarly journals Doping of GaN by Ion Implantation: Does it Work?

1998 ◽  
Vol 512 ◽  
Author(s):  
A. Suvkhanov ◽  
J. Hunn ◽  
W. Wu ◽  
D. Thomson ◽  
K. Price ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Elevated Temperatures ◽  
Nitrogen Loss ◽  
Chemical Vapor ◽  
High Sensitivity ◽  
Liquid Nitrogen Temperature ◽  
Organic Chemical ◽  
Damage Level ◽  
In Doping ◽  
Annealing Effects

ABSTRACTEpitaxially grown GaN by metal organic chemical vapor deposition (MOCVD) on SiC were implanted with 100 keV Si+ (for n-type) and 80 keV Mg+ (for p-type) with various fluences from 1×1012 to 7×1015 ions/cm2 at liquid nitrogen temperature (LT), room temperature (RT), and 700 °C (HT). High temperature (1200 °C and 1500 °C) annealing was carried out after capping the GaN with epitaxial AIN by MOCVD to study damage recovery. Samples were capped by a layer of AIN in order to protect the GaN surface during annealing. Effects of implant temperature, damage and dopant activation are critically studied to evaluate a role of ion implantation in doping of GaN. The damage was studied by Rutherford Backscattering/Channeling, spectroscopic ellipsometry and photoluminescence. Results show dependence of radiation damage level on temperature of the substrate during implantation: implantations at elevated temperatures up to 550 °C decrease the lattice disorder; “hot implants” above 550 °C can not be useful in doping of GaN due to nitrogen loss from the surface. SE measurements have indicated very high sensitivity to the implantation damage. PL measurements at LT of 80 keV Mg+ (5×1014 cm-2) implanted and annealed GaN showed two peaks : one ∼100 meV and another ∼140 meV away from the band edge.

Oxidation protective barrier coatings for high-temperature polymer matrix composites

1994 ◽  
Vol 9 (6) ◽  
pp. 1583-1595 ◽  
Author(s):  
David R. Harding ◽  
James K. Sutter ◽  
Marla A. Schuerman ◽  
Elizabeth A. Crane
Keyword(s):  
Chemical Vapor Deposition ◽  
Silicon Nitride ◽  
Vapor Deposition ◽  
Elevated Temperatures ◽  
Polymer Matrix Composites ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Coating Materials ◽  
Factors Affecting ◽  
Major Factors

Three coating techniques (metal-organic chemical vapor deposition, magnetron sputtering, and plasma-enhanced chemical vapor deposition) were employed to deposit different coating materials (alumina, a superalloy, and silicon nitride) on graphite-fiber-reinforced polyimide composites to protect against oxidation at elevated temperatures. Adhesion and integrity of the coatings were evaluated by isothermal aging (371 °C for 500 h) and thermal cycling (25 to 232 °C for 1000 cycles and −18 to 232 °C for 300 cycles). Best results were achieved with a plasma-deposited, amorphous silicon nitride (a-SiN: H) coating, which withstood stresses from 0.18 to −1.6 GPa. The major factors affecting the suitability of a-SiN: H as an oxidation protective coating are the surface finish of the polymer composite and the presence of a sizable hydrogen content in the coating.

scholarly journals Fabrication and Characterization of GaN Junctionfield Effect Transistors

2000 ◽  
Vol 5 (S1) ◽  
pp. 376-383
Author(s):  
L. Zhang ◽  
L. F. Lester ◽  
A. G. Baca ◽  
R. J. Shul ◽  
P. C. Chang ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Field Effect Transistors ◽  
Chemical Vapor ◽  
Drain Current ◽  
Organic Chemical ◽  
Microwave Measurement ◽  
Theoretical Predictions ◽  
Metal Organic ◽  
Current Reduction ◽  
Increasing Temperature

Junction field effect transistors (JFET) were fabricated on a GaN epitaxial structure grown by metal organic chemical vapor deposition. The DC and microwave characteristics, as well as the high temperature performance of the devices were studied. These devices exhibited excellent pinch-off and a breakdown voltage that agreed with theoretical predictions. An extrinsic transconductance (gm) of 48 mS/mm was obtained with a maximum drain current (ID) of 270 mA/mm. The microwave measurement showed an fT of 6 GHz and an fmax of 12 GHz. Both the ID and the gm were found to decrease with increasing temperature, possibly due to lower electron mobility at elevated temperatures. These JFETs exhibited a significant current reduction after a high drain bias was applied, which was attributed to a partially depleted channel caused by trapped electrons in the semi-insulating GaN buffer layer.

Formation of Gallium Nitride (GaN) Transition Layer by Plasma Immersion Ion Implantation and Rapid Thermal Annealing

2000 ◽  
Vol 618 ◽  
Author(s):  
D. T. K. Kwok ◽  
A. H. P. Ho ◽  
X. C. Zeng ◽  
C. Chan ◽  
P. K. Chu ◽  
...  
Keyword(s):  
Gallium Nitride ◽  
Ion Implantation ◽  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Ion Beam ◽  
Chemical Vapor ◽  
Crystal Form ◽  
Organic Chemical ◽  
Plasma Immersion Ion Implantation ◽  
Amorphous Surface

ABSTRACTRecent advances in the preparation of gallium nitride (GaN) and related compounds have made possible the production of blue semiconductor laser. Conventional preparation involves growing GaN thin films on lattice-mismatching sapphire using metal-organic chemical vapor deposition (MOCVD). In this article, we describe an alternative method to produce a lattice-matching strained layer in GaAs for subsequent GaN growth by plasma immersion ion implantation (PIII) followed by rapid thermal annealing. Our novel approach uses broad ion impact energy distribution and multiple implant voltages to form a spread-out nitrogen depth profile and an amorphous surface layer. This approach circumvents the retained dose and low nitrogen content problems associated with ion beam implantation at fix energy. Based on our Raman study, the resulting structure after PIII and rapid thermal annealing is strained and contains some GaN possibly in crystal form

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