Effect of buffer layer structure on the structural properties of GaAs epitaxial layers grown on GaP substrates

High-quality epitaxial layers are directly related to internal quantum efficiency. The methods used to design such epitaxial layers are reviewed in this article. The ultraviolet C (UVC) light-emitting diode (LED) epitaxial layer structure exhibits electron leakage; therefore, many research groups have proposed the design of blocking layers and carrier transportation to generate high electron–hole recombination rates. This also aids in increasing the internal quantum efficiency. The cap layer, p-GaN, exhibits high absorption in deep UV radiation; thus, a small thickness is usually chosen. Flip chip design is more popular for such devices in the UV band, and the main factors for consideration are light extraction and heat transportation. However, the choice of encapsulation materials is important, because unsuitable encapsulation materials will be degraded by ultraviolet light irradiation. A suitable package design can account for light extraction and heat transportation. Finally, an atomic layer deposition Al2O3 film has been proposed as a mesa passivation layer. It can provide a low reverse current leakage. Moreover, it can help increase the quantum efficiency, enhance the moisture resistance, and improve reliability. UVC LED applications can be used in sterilization, water purification, air purification, and medical and military fields.

Download Full-text

Effect of the nand p-type Si(100) substrates with a SiC buffer layer on the growth mechanism and structure of epitaxial layers of semipolar AlN and GaN

Physics of the Solid State ◽

10.1134/s1063783415100042 ◽

2015 ◽

Vol 57 (10) ◽

pp. 1966-1971 ◽

Cited By ~ 2

Author(s):

V. N. Bessolov ◽

A. S. Grashchenko ◽

E. V. Konenkova ◽

A. V. Myasoedov ◽

A. V. Osipov ◽

...

Keyword(s):

Buffer Layer ◽

Growth Mechanism ◽

Epitaxial Layers ◽

P Type

Download Full-text

Magnetic Anisotropy in Electrodeposited CO Films and spin-valves on Gaas Substrates

MRS Proceedings ◽

10.1557/proc-562-21 ◽

1999 ◽

Vol 562 ◽

Cited By ~ 2

Author(s):

K. Attenborough ◽

M. Cerisier ◽

H. Boeve ◽

J. De Boeck ◽

G. Borghs ◽

...

Keyword(s):

Magnetic Anisotropy ◽

Buffer Layer ◽

Structural Properties ◽

Easy Axis ◽

Spin Valve ◽

X Ray Diffraction ◽

X Ray ◽

Cu Films ◽

Gaas Substrates ◽

Unique Spin

ABSTRACTWe have studied the magnetic and structural properties of thin electrodeposited Co and Cu layers grown directly onto (100) n-GaAs and have investigated the influence of a buffer layer. A dominant fourfold anisotropy with a uniaxial contribution is observed in 10 nm Co electrodeposited films on GaAs. An easy axis is observed in the [001] GaAs direction with two hard axes of differing coercivities parallel to the [011] and [011] directions. For thicker films the easy axes in the [001] direction becomes less pronounced and the fourfold anisotropy becomes less dominant. Co films of similar thicknesses deposited onto an electrodeposited Cu buffer layer were nearly isotropic. From X-ray diffraction 21 nm Co layers on GaAs were found to be hcp with the c-axis tending to be in the plane of the film. The anisotropy is ascribed to the Co/GaAs interface and is held responsible for the unique spin-valve properties seen recently in electrodeposited Co/Cu films.

Download Full-text

Influence of AlN buffer layer thickness on structural properties of GaN epilayer grown on Si (111) substrate with AlGaN interlayer

Chinese Physics B ◽

10.1088/1674-1056/19/3/036801 ◽

2010 ◽

Vol 19 (3) ◽

pp. 036801 ◽

Cited By ~ 3

Author(s):

Wu Yu-Xin ◽

Zhu Jian-Jun ◽

Chen Gui-Feng ◽

Zhang Shu-Ming ◽

Jiang De-Sheng ◽

...

Keyword(s):

Buffer Layer ◽

Layer Thickness ◽

Structural Properties ◽

Buffer Layer Thickness ◽

Aln Buffer

Download Full-text

Growth and Characterization of Uniform Carbon Nanotube Arrays on Active Substrates

MRS Proceedings ◽

10.1557/opl.2015.291 ◽

2015 ◽

Vol 1752 ◽

pp. 3-14

Author(s):

Qiuhong Zhang ◽

Betty T. Quinton ◽

Bang-Hung Tsao ◽

James Scofield ◽

Neil Merrett ◽

...

Keyword(s):

Buffer Layer ◽

Layer Structure ◽

Substrate Surface ◽

Composite Layer ◽

Carbon Composite ◽

Thermal Interface Material ◽

Chemical Vapor Deposition Method ◽

Sem Images ◽

Reactive Material ◽

Aspect Ratios

ABSTRACTCarbon nanotubes (CNTs) have unique thermal/electrical/mechanical properties and high aspect ratios. Growth of CNTs directly onto reactive material substrates (such as metals and carbon based foam structures, etc.) to create a micro-carbon composite layer on the surface has many advantages: possible elimination of processing steps and resistive junctions, provision of a thermally conductive transition layer between materials of varying thermal expansion coefficients, etc. Compared to growing CNTs on conventional inert substrates such as SiO2, direct growth of CNTs onto reactive substrates is significantly more challenging. Namely, control of CNT growth, structure, and morphology has proven difficult due to the diffusion of metallic catalysts into the substrate during CNT synthesis conditions. In this study, using a chemical vapor deposition method, uniform CNT layers were successfully grown on copper foil and carbon foam substrates that were pre-coated with an appropriate buffer layer such as Al2O3 or Al. SEM images indicated that growth conditions and, most notably, substrate surface pre-treatment all influence CNT growth and layer structure/morphology. The SEM images and pull-off testing results revealed that relatively strong bonding existed between the CNT layer and substrate material, and that normal interfacial adhesion (0.2‒0.5 MPa) was affected by the buffer layer thickness. Additionally, the thermal properties of the CNT/substrate structure were evaluated using a laser flash technique, which showed that the CNT layer can reduce thermal resistance when used as a thermal interface material between bonded layers.

Download Full-text

Enhanced optical and structural properties of V-doped binary SnS2 buffer layer

Solar Energy ◽

10.1016/j.solener.2020.04.095 ◽

2020 ◽

Vol 204 ◽

pp. 654-659 ◽

Cited By ~ 1

Author(s):

Shafi Ullah ◽

Amal Bouich ◽

Hanif Ullah ◽

Bernabé Mari ◽

Miguel Mollar

Keyword(s):

Buffer Layer ◽

Structural Properties

Download Full-text

Epitaxial growth of metallic buffer layer structure andc-axis oriented Pb(Mn1/3,Nb2/3)O3–Pb(Zr,Ti)O3thin film on Si for high performance piezoelectric micromachined ultrasonic transducer

Japanese Journal of Applied Physics ◽

10.7567/jjap.56.127201 ◽

2017 ◽

Vol 56 (12) ◽

pp. 127201 ◽

Cited By ~ 2

Author(s):

Pham Ngoc Thao ◽

Shinya Yoshida ◽

Shuji Tanaka

Keyword(s):

Epitaxial Growth ◽

Buffer Layer ◽

High Performance ◽

Layer Structure ◽

Ultrasonic Transducer

Download Full-text

Strain in Epitaxial GaAs on CaF2/Si(111)

MRS Proceedings ◽

10.1557/proc-160-527 ◽

1989 ◽

Vol 160 ◽

Author(s):

L.J. Schowalter ◽

J.E. Ayers ◽

S.K. Ghandhi ◽

Shin Hashimoto ◽

W.M. Gibson ◽

...

Keyword(s):

Layer Structure ◽

High Energy ◽

Buffer Layers ◽

Epitaxial Layers ◽

X Ray Diffraction ◽

Double Crystal ◽

Ion Channeling ◽

Gaas Films ◽

Mev Protons ◽

Good Agreement

AbstractEpitaxial layers of (111) GaAs of approximately 1 µm thickness were grown on epitaxial CaF2 buffer layers which were either 140 or 380 nm thick on Si(111) substrates. The best nucleation temperature for the GaAs on CaF2/Si(111) we have observed was 620 °C. This resulted in high quality GaAs films which exhibited channeling minimum yields of 4%. The density of threading dislocations in the GaAs layers was observed by TEM to be ~108 cm-2. Double-crystal x-ray diffraction measurements showed that the strain (ε┴.) was less than 2.2×10-4 in both sets of GaAs samples. Ion channeling, however, revealed a large tetragonal strain of 3.5×10-3 (ε┴ = 1.7×10-3) in the thinner (140 nm) CaF2 buffer layers. By doing ion channeling with high energy (2.5 MeV) protons, it was possible to determine strain more accurately. Using this technique, we were able to set an upper limit for the tetragonal strain of 2.5×10-4 in both the GaAs (which implies ε┴ < 8×10-5 and CaF2 (ε┴ < 1.5×10-4) layers for the thicker (380 nm) CaF2 buffer layer structure. These results are in good agreement with the strain predicted from previous strain measurements of CaF2 epitaxial layers on Si.

Download Full-text