scholarly journals Mosaic Defects of AlN Buffer Layers in GaN/AlN/4H-SiC Epitaxial Structure

2021 ◽  
pp. 1-1
Author(s):  
Tuğçe ATAŞER ◽  
Durmuş DEMİR ◽  
Ahmet Kursat BILGILI ◽  
Mustafa ÖZTÜRK ◽  
Süleyman ÖZÇELİK
Keyword(s):  
Buffer Layers ◽  
Epitaxial Structure ◽  
Aln Buffer

Exciton dynamics in thick GaN MOVPE epilayers deposited on sapphire.

1997 ◽  
Vol 2 ◽  
Author(s):  
J. Allègre ◽  
P. Lefebvre ◽  
J. Camassel ◽  
B. Beaumont ◽  
Pierre Gibart
Keyword(s):  
Layer Thickness ◽  
Buffer Layers ◽  
Rate Equations ◽  
Time Resolved ◽  
Versus Layer ◽  
Level Model ◽  
Shallow Impurities ◽  
Aln Buffer ◽  
Time Resolved Photoluminescence

Time-resolved photoluminescence spectra have been recorded on three GaN epitaxial layers of thickness 2.5 μm, 7 μm and 16 μm, at various temperatures ranging from 8K to 300K. The layers were deposited by MOVPE on (0001) sapphire substrates with standard AlN buffer layers. To achieve good homogeneities, the growth was in-situ monitored by laser reflectometry. All GaN layers showed sharp excitonic peaks in cw PL and three excitonic contributions were seen by reflectivity. The recombination dynamics of excitons depends strongly upon the layer thickness. For the thinnest layer, exponential decays with τ ~ 35 ps have been measured for both XA and XB free excitons. For the thickest layer, the decay becomes biexponential with τ1 ~ 80 ps and τ2 ~ 250 ps. These values are preserved up to room temperature. By solving coupled rate equations in a four-level model, this evolution is interpreted in terms of the reduction of density of both shallow impurities and deep traps, versus layer thickness, roughly following a L−1 law.

Effects of the Sputtering Time of AlN Buffer Layer on the Quality of ZnO Thin Films

2014 ◽  
Vol 881-883 ◽  
pp. 1117-1121 ◽  
Author(s):  
Xiang Min Zhao
Keyword(s):  
Thin Films ◽  
Buffer Layer ◽  
Rf Magnetron Sputtering ◽  
Buffer Layers ◽  
Zno Thin Films ◽  
Zno Films ◽  
Si Substrates ◽  
Atomic Force ◽  
Structure Morphology ◽  
Aln Buffer

ZnO thin films with different thickness (the sputtering time of AlN buffer layers was 0 min, 30 min,60 min, and 90 min, respectively) were prepared on Si substrates using radio frequency (RF) magnetron sputtering system.X-ray diffraction (XRD), atomic force microscope (AFM), Hall measurements setup (Hall) were used to analyze the structure, morphology and electrical properties of ZnO films.The results show that growth are still preferred (002) orientation of ZnO thin films with different sputtering time of AlN buffer layer,and for the better growth of ZnO films, the optimal sputtering time is 60 min.

III-Nitride Growth on Lithium Niobate: A New Substrate Material for Polarity Engineering in III-Nitride Heteroepitaxy

2002 ◽  
Vol 743 ◽  
Author(s):  
W. Alan Doolittle ◽  
Gon Namkoong ◽  
Alexander Carver ◽  
Walter Henderson ◽  
Dieter Jundt ◽  
...  
Keyword(s):  
Lithium Niobate ◽  
Lattice Mismatch ◽  
Substrate Material ◽  
Buffer Layers ◽  
Initial Growth ◽  
Periodically Poled ◽  
Film Adhesion ◽  
Electro Optic ◽  
Bandgap Semiconductors ◽  
Aln Buffer

ABSTRACTHerein, we discuss the use of a novel new substrate for III-Nitride epitaxy, Lithium Niobate. It is shown that Lithium Niobate (LN) has a smaller lattice mismatch to III-Nitrides than sapphire and can be used to control the polarity of III-Nitride films grown by plasma assisted molecular beam epitaxy. Results from initial growth studies are reported including using various nitridation/buffer conditions along with structural and optical characterization. Comparisons of data obtained from GaN and AlN buffer layers are offered and details of the film adhesion dependence on buffer layer conditions is presented. Lateral polarization heterostructures grown on periodically poled LN are also demonstrated. While work is still required to establish the limits of the methods proposed herein, these initial studies offer the promise for mixing III-Nitride semiconductor materials with lithium niobate allowing wide bandgap semiconductors to utilize the acoustic, pyroelectric/ferroelectric, electro-optic, and nonlinear optical properties of this new substrate material as well as the ability to engineer various polarization structures for future devices.

Reduction of the defect density in GaN films using ultra-thin AlN buffer layers on 6H-SiC

1997 ◽  
Vol 170 (1-4) ◽  
pp. 329-334 ◽  
Author(s):  
Satoru Tanaka ◽  
Sohachi Iwai ◽  
Yoshinobu Aoyagi
Keyword(s):  
Defect Density ◽  
Buffer Layers ◽  
Aln Buffer

Investigation of AlN buffer layers on 6H-SiC for AlInN HEMTs grown by MOVPE

2011 ◽  
Vol 316 (1) ◽  
pp. 42-45 ◽  
Author(s):  
H. Behmenburg ◽  
C. Giesen ◽  
R. Srnanek ◽  
J. Kovac ◽  
H. Kalisch ◽  
...  
Keyword(s):  
Buffer Layers ◽  
Aln Buffer

Growth and Characterization of GaN on Si(111)

1994 ◽  
Vol 339 ◽  
Author(s):  
A. Ohtani ◽  
K. S. Stevens ◽  
R. Beresford
Keyword(s):  
Growth Temperature ◽  
Electron Cyclotron Resonance ◽  
Microwave Plasma ◽  
Buffer Layers ◽  
X Ray Diffraction ◽  
Ion Density ◽  
Nitrogen Ion ◽  
Gan On Si ◽  
Aln Buffer

ABSTRACTWurtzite GaN films on AlN buffer layers were grown on Si (111) by electron cyclotron resonance microwave plasma assisted MBE (ECR-MBE). High resolution x-ray diffraction studies indicate that the mosaic disorder decreases with increasing growth temperature. The grain size is related to the growth temperature. The best (0002) diffraction peak full width at half maximum was 22 min. for a film 1.7 μm thick. Prominent exciton luminescence is observed at 3.46 eV at 10 K.The plasma I-V characteristics were measured with a Langmuir probe near the growth position. The nitrogen ion density has been extracted from the data, and is a strong function of the N2 flow rate, the microwave power and the aperture size of the ECR source. The crystal quality of AlN is strongly affected by the plasma conditions.

Microstructure of GaN epitaxy on SiC using AlN buffer layers

1995 ◽  
Vol 67 (3) ◽  
pp. 410-412 ◽  
Author(s):  
F. A. Ponce ◽  
B. S. Krusor ◽  
J. S. Major ◽  
W. E. Plano ◽  
D. F. Welch
Keyword(s):  
Buffer Layers ◽  
Aln Buffer

GaN ON SILICON SUBSTRATE WITH AlN BUFFER LAYER FOR UV PHOTODIODE

2012 ◽  
Vol 21 (01) ◽  
pp. 1250014 ◽  
Author(s):  
L. S. CHUAH ◽  
S. M. THAHAB ◽  
Z. HASSAN
Keyword(s):  
Schottky Barrier ◽  
Buffer Layer ◽  
Barrier Height ◽  
Silicon Substrate ◽  
Dark Current ◽  
Schottky Barrier Height ◽  
Buffer Layers ◽  
Current Ratio ◽  
Principal Mechanism ◽  
Aln Buffer

Nitrogen plasma-assisted molecular beam epitaxy (PAMBE) deposited GaN thin films on (111) n-type silicon substrate with different thickness AlN buffer layers are investigated and distinguished by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and Raman scattering. The thickness of AlN buffer layer ranged from 200 nm to 300 nm. Besides that, the electrical characteristics of the GaN thin film for ultraviolet detecting utilizations are studied by calculating the photo current/dark current ratio on a metal-semiconductor-metal (MSM) photodiode with and without the illumination of Hg-lamp source. The devices have been tested over room temperature (RT). The photocurrent analysis, together with the study of Schottky barrier height (SBH) development, ascertain that the principal mechanism of photo transport is thermionic emission. The photocurrent value is rigorously dependent on Schottky barrier height. The GaN/AlN(200 nm)/n-Si MSM photodiode produces the highest photo/dark current ratio for the lowest strain that consists of the GaN film grown on the AlN (200 nm) buffer layer.

scholarly journals Effect of Buffer Layer and III/V Ratio on the Surface Morphology of Gan Grown by MBE

1999 ◽  
Vol 4 (S1) ◽  
pp. 417-422 ◽  
Author(s):  
E. C. Piquette ◽  
P. M. Bridger ◽  
R. A. Beach ◽  
T. C. McGill
Keyword(s):  
Surface Morphology ◽  
Buffer Layer ◽  
Flux Ratio ◽  
Plasma Source ◽  
Growth Conditions ◽  
Nitrogen Plasma ◽  
Layer Growth ◽  
Buffer Layers ◽  
Flat Surfaces ◽  
Aln Buffer

The surface morphology of GaN is observed by atomic force microscopy for growth on GaN and AlN buffer layers and as a function of III/V flux ratio. Films are grown on sapphire substrates by molecular beam epitaxy using a radio frequency nitrogen plasma source. Growth using GaN buffer layers leads to N-polar films, with surfaces strongly dependent on the flux conditions used. Flat surfaces can be obtained by growing as Ga-rich as possible, although Ga droplets tend to form. Ga-polar films can be grown on AlN buffer layers, with the surface morphology determined by the conditions of buffer layer deposition as well as the III/V ratio for growth of the GaN layer. Near-stoichiometric buffer layer growth conditions appear to support the flattest surfaces in this case. Three defect types are typically observed in GaN films on AlN buffers, including large and small pits and “loop” defects. It is possible to produce surfaces free from large pit defects by growing thicker films under more Ga-rich conditions. In such cases the surface roughness can be reduced to less than 1 nm RMS.

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