Growth of GaN film on a-plane sapphire substrates by plasma-assisted MOCVD

AbstractThe epitaxial lateral overgrowth (ELO) process for GaN has been studied using SiC and sapphire substrates. Both MBE and MOVPE growth processes were employed in the study. The use of SiO2 versus SiNx insulator stripes was investigated using window/stripe widths ranging from 2 μm/4 μm to 3 μm/15 μm. GaN film depositions were completed at temperatures ranging from 800°C to 1120°C. Characterization experiments included RHEED, TEM, SEM and cathodolumenescence studies. The MBE growth experiments produced polycrystalline GaN over the insulator stripes even at deposition temperatures as high as 990°C. In contrast, MOVPE growth produced single-crystal GaN stripes with no observable threading dislocations.

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On Compensation and Impurities in State-of-the-Art GaN Epilayers Grown on Sapphire

MRS Proceedings ◽

10.1557/proc-395-679 ◽

1995 ◽

Vol 395 ◽

Cited By ~ 24

Author(s):

A.E. Wickenden ◽

D.K. Gaskill ◽

D.D. Koleske ◽

K. Doverspike ◽

D.S. Simons ◽

...

Keyword(s):

Activation Energy ◽

Electron Transport ◽

State Of The Art ◽

Theoretical Calculations ◽

Recent Analysis ◽

Silicon Doping ◽

Sapphire Substrates ◽

Silicon Doped ◽

Gan Film

ABSTRACTA comparison between 300 K electron transport data for state-of-the-art wurtzite GaN grown on sapphire substrates and corresponding theoretical calculations shows a large difference, with experimental mobility less than the predicted mobility for a given carrier concentration. The comparison seems to imply that GaN films are greatly compensated, but the discrepancy may also be due to the poorly known values of the materials parameters used in the calculations. In this work, recent analysis of transport and SIMS measurements on silicon-doped GaN films are shown to imply that the compensation, NA/ND, is less than 0.3. In addition, the determination of an activation energy of 34 meV in a GaN film doped to a level of 6×1016 cm−3 suggests either that a second, native donor exists in the doped films at a level of between 6×1017 cm−3 and 1×1017 cm−3, or that the activation energy of Si in GaN is dependent on the concentration, being influenced by impurity banding or some other physical effect. GaN films grown without silicon doping are highly resistive.

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A Model for the Critical Height for Dislocation Annihilation and Recombination in GaN Columns Deposited by Patterned Growth

MRS Proceedings ◽

10.1557/proc-831-e11.29 ◽

2004 ◽

Vol 831 ◽

Cited By ~ 1

Author(s):

M. E. Twigg ◽

N. D. Bassim ◽

C. R. Eddy ◽

R. L. Henry ◽

R. T. Holm ◽

...

Keyword(s):

Grain Size ◽

Dislocation Density ◽

Column Height ◽

Critical Height ◽

Patterned Growth ◽

Sapphire Substrates ◽

Density Reduction ◽

Vertical Leakage ◽

Dislocation Annihilation ◽

Gan Film

ABSTRACTIn order to reduce vertical leakage in III-nitride detectors, we have grown a patterned array of hexagonal GaN columns on masked heteroepitaxial GaN template layers using a-plane sapphire substrates. In addition to eliminating cracking, we have found that for GaN columns tens of microns in diameter and several microns high, the dislocation density is also significantly reduced. We have developed a simple closed-form analytical model for predicting the critical column height for the onset of the reduction in the dislocation density. Among the predictions of this model is that the critical column height for the onset of dislocation density reduction is proportional to the product of column width and the grain size of the GaN film.

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High quality MOCVD GaN film grown on sapphire substrates using HT-AlN buffer layer

Journal of Non-Crystalline Solids ◽

10.1016/j.jnoncrysol.2006.01.099 ◽

2006 ◽

Vol 352 (23-25) ◽

pp. 2332-2334 ◽

Cited By ~ 12

Author(s):

B. Potì ◽

M.A. Tagliente ◽

A. Passaseo

Keyword(s):

Buffer Layer ◽

High Quality ◽

Sapphire Substrates ◽

Aln Buffer ◽

Gan Film

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Effects of the inclination direction of vicinal m-plane sapphire substrates on the crystal quality of m-plane GaN film

Journal of Crystal Growth ◽

10.1016/j.jcrysgro.2011.04.034 ◽

2011 ◽

Vol 325 (1) ◽

pp. 85-88 ◽

Cited By ~ 1

Author(s):

Youngji Cho ◽

Sungkuk Choi ◽

Gyung-Suk Kil ◽

Hyun-Jae Lee ◽

Takafumi Yao ◽

...

Keyword(s):

Crystal Quality ◽

Sapphire Substrates ◽

Gan Film

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Electric Field Induced Heating and Energy Relaxation in GaN

MRS Proceedings ◽

10.1557/proc-693-i11.25.1 ◽

2001 ◽

Vol 693 ◽

Author(s):

T. A. Eckhause ◽

Ö. Süzer ◽

Ç. Kurdak ◽

F. Yun ◽

H. Morkoç

Keyword(s):

Low Temperature ◽

Electric Field ◽

Power Dissipation ◽

Electron Gas ◽

Potential Scattering ◽

Excess Noise ◽

3 Dimensional ◽

Sapphire Substrates ◽

Dimensional Electron Gas ◽

Gan Film

AbstractWe report results of an investigation of electric field induced heating at low temperature in GaN 3-dimensional electron gas films grown on sapphire substrates. The excess noise of the electron gas in a patterned GaN film, while the substrate is held at low temperature, is used to determine the electron temperature. We calculate the rate of power dissipation and compare our results with a calculation of acoustic deformation potential scattering processes in GaN. We discuss the existence of a thermal boundary resistance between the GaN film and the sapphire substrate.

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The Effect of a GaN Nucleation Layer on GaN Film Properties Grown by Metalorganic Chemical Vapor Deposition

MRS Proceedings ◽

10.1557/proc-395-231 ◽

1995 ◽

Vol 395 ◽

Cited By ~ 9

Author(s):

W. Van Der Stricht ◽

I. Moerman ◽

P. Demeester ◽

J.A Crawley ◽

E.J. Thrush ◽

...

Keyword(s):

Metalorganic Chemical Vapor Deposition ◽

Chemical Vapor ◽

Rotating Disk ◽

X Ray Diffraction ◽

Film Properties ◽

Double Crystal ◽

Nucleation Layer ◽

X Ray ◽

Sapphire Substrates ◽

Gan Film

ABSTRACTIn this paper GaN films are examined, which are grown on basal plane (0001) sapphire substrates. Growth is performed in a novel type of vertical rotating disk reactor. Results on the effect of a GaN nucleation layer on the properties of the overgrown GaN epilayer are presented. Characterisation includes surface morphology studies, DC X-ray diffraction and optical characterisation. Best film quality so far has a double crystal X-ray half width of 85 arcsec at approximately 1 μm thickness.

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Structural Anisotropy and Optical Properties of Nonpolar a-Plane GaN Epitaxial Layers

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2015.11188 ◽

2015 ◽

Vol 15 (10) ◽

pp. 7787-7790 ◽

Cited By ~ 1

Author(s):

Yong Gon Seo ◽

Sun Hye Shin ◽

Doo Soo Kim ◽

Hyung-Do Yoon ◽

Sung-Min Hwang ◽

...

Keyword(s):

Optical Properties ◽

Compressive Strain ◽

Dangling Bond ◽

Structural Anisotropy ◽

X Ray ◽

Sapphire Substrates ◽

Pl Intensity ◽

Peak Widths ◽

Gan Film ◽

Specific Crystal Orientation

In-plane structural anisotropy is characteristic of nonpolar (1120) a-plane GaN (a-GaN) films grown on r-plane sapphire substrates. The anisotropic peak broadenings of X-ray rocking curves (XRCs) are clearly observed with M- or W-shaped dependence on the azimuth angles. We investigated the optical properties of both M- and W-shaped a-GaN samples with room and low-temperature photoluminescence (PL) measurements. The W-shaped a-GaN film showed higher PL intensity and more compressive strain compared to the M-shaped a-GaN film, whereas the XRC peak widths of the M-shaped a-GaN film on the azimuth angles are lower than those of W-shaped specimens, indicating that better crystalline quality was obtained. We speculate that the PL intensity and strain state of a-GaN layers may be more influenced by the crystallinity of a specific crystal orientation or direction, especially along the m-axis as opposed to the c-axis. This occurrence is most likely due to anisotropic defect distributions, resulting from differences in dangling bond densities of (0001) and {1-100} facets.

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Characterization of the N-polar GaN film grown on C-plane sapphire and misoriented C-plane sapphire substrates by MOCVD

Chinese Physics B ◽

10.1088/1674-1056/ac3bad ◽

2021 ◽

Author(s):

Xiaotao Hu ◽

Yimeng Song ◽

Zhaole Su ◽

Haiqiang Jia ◽

Wenxin Wang ◽

...

Keyword(s):

Misorientation Angle ◽

Tilt Angle ◽

Coherence Length ◽

Lattice Strain ◽

Crystalline Quality ◽

Organic Chemical ◽

X Ray Diffraction ◽

X Ray ◽

Sapphire Substrates ◽

Gan Film

Abstract Gallium nitride (GaN) thin film of the nitrogen polarity (N-polar) was grown on C-plane sapphire and misoriented C-plane sapphire substrates respectively by metal-organic chemical vapor deposition (MOCVD). The misorientation angle is off-axis from C-plane toward M-plane of the substrates, and the angle is 2° and 4° respectively. The nitrogen polarity was confirmed by examining the images of the scanning electron microscope before and after the wet etching in potassium hydroxide (KOH) solution. The morphology was studied by the optical microscope and atomic force microscope. The crystalline quality was characterized by the X-ray diffraction. The lateral coherence length, the tilt angle, the vertical coherence length, and the vertical lattice-strain were acquired using the pseudo-Voigt function to fit the X-ray diffraction curves and then calculating with four empirical formulae. The lateral coherence length increases with the misorientation angle, because higher step density and shorter distance between adjacent steps can lead to larger lateral coherence length. The tilt angle increases with the misorientation angle, which means that the misoriented substrate can degrade the identity of crystal orientation of the N-polar GaN film. The vertical lattice-strain decreases with the misorientation angle. The vertical coherence length does not change a lot as the misorientation angle increases and this value of all samples is near to the nominal thickness of the N-polar GaN layer. This study helps to understand the influence of the misorientation angle of misoriented C-plane sapphire on the morphology, the crystalline quality, and the microstructure of N-polar GaN films.

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