Effect of Basal-plane Stacking Faults on X-ray Diffraction of Non-polar (1120) a-plane GaN Films Grown on (1102) r-plane Sapphire Substrates

Kim, Ji Hoon; Hwang, Soon Jung; Baik, Kwang Hyeon; Park, Jung Ho

doi:10.5573/jsts.2014.14.5.557

Cited by 11 publications

(6 citation statements)

References 29 publications

(53 reference statements)

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“…There are staking faults in the a -plane GaN which are generated during the growth procedure as a zinc blende insertion with compressive strain, they are parallel to the growth direction and hence perpendicular to the [0002] azimuth direction (Figure ). ,, It is very well known that at the interface there is a spontaneous polarization along the [0002] direction in III-nitrides. These small walls of stacking faults behave in a similar fashion and create a polarization center with a built-in electric field acting along the [0002] direction. − In turn, the overall effect of the built-in electric field acting along [0002] would push the electrons toward one of the electrodes.…”

Section: Resultsmentioning

confidence: 99%

“… ,, It is very well known that at the interface there is a spontaneous polarization along the [0002] direction in III-nitrides. These small walls of stacking faults behave in a similar fashion and create a polarization center with a built-in electric field acting along the [0002] direction. − In turn, the overall effect of the built-in electric field acting along [0002] would push the electrons toward one of the electrodes. As the electrons will accumulate near the edge of the electrode, it will eventually reduce the Schottky barrier height.…”

Section: Resultsmentioning

confidence: 99%

“…The highest responsivity of ∼400 A W –1 was observed at 5 V, 364 nm and the IV characteristics, temporal responses at 0 bias confirm the self-powered UV detection in these devices. Polarization generated because of basal plane defects pushes the electrons toward one of the Au/GaN Schottky barriers which in turn would create asymmetric electrodes. − This generates an effective total electric field along one direction and separates the photogenerated e–h pair at zero bias. Overall, robust self-powered metal semiconductor metal (Au/GaN) UV-A photodetectors can be realized with the exploitation of [0002] azimuth and the polarization centers created at basal plane defects.…”

Section: Introductionmentioning

confidence: 99%

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Highly Responsive, Self-Powered a-GaN Based UV-A Photodetectors Driven by Unintentional Asymmetrical Electrodes

Pant

Singh

Chowdhury

et al. 2020

ACS Appl. Electron. Mater.

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Optoelectronic properties of nonpolar a-plane GaN are superior along the [0002] azimuth direction compared to other azimuth directions. We have grown a-GaN on r-sapphire, and interdigitated electrode patterns of Au were fabricated to restrict the carrier transport only along [0002] azimuth. Surprisingly, the Schottky barriers of Au/GaN were found to be asymmetric in nature as the current on the positive side was different than negative for the same bias. Polarization on the boundaries of the basal plane defects has been already investigated for the possible reason of the Schottky barrier inhomogeneity. Thus, it can be expected that the overall effect of these polarization centers would change the Schottky barrier height of one of the electrodes. Electronic band-alignment based on asymmetrical contacts reveals that the difference in the Schottky barrier height would create a net electrical field toward the higher Schottky barrier, which is exploited here for self-powered photodetection and also enhanced photodetection at higher applied bias. The spectral response of all the devices was studied within 300–700 nm, and it was found that spectral response enhances with the applied voltage. The maximum responsivity and detectivity for a 364 nm light source observed at 5 V was around 400 A W–1 and 6.6 × 1012 jones, while at 0 V, it was 4.67 mA W–1 and 3.0 × 1013 jones, respectively, which is the highest known responsivity for a-plane GaN to the best of our knowledge. The spectral response shows that the devices work for a very narrow band of radiation and hence can be used for selective UV-A photodetection. Overall, these results demonstrate much-improved UV photodetection properties compared to existing GaN-based photodetectors.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Highly Responsive, Self-Powered a-GaN Based UV-A Photodetectors Driven by Unintentional Asymmetrical Electrodes

Pant

Singh

Chowdhury

et al. 2020

ACS Appl. Electron. Mater.

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“…The XRC ω-scan was performed at phi angle intervals of 30°, where the X-ray beam was placed parallel to the c - and m -axes along the (11–20) plane at 0° and 90° phi angles, respectively. The FWHM plot exhibits the same trend as the nonpolar XRC measurements, that is, the anisotropy of nonpolar GaN results in an “M”-shaped plot with respect to the phi angle 10 , 15 , 31 . The lowest FWHMs are observed at a phi angle of 0°, corresponding to 1224, 1044, 864 and 756 arcsec for samples S1, S2, S3 and S4, respectively.…”

Section: Resultsmentioning

confidence: 53%

“…However, the growth of a -plane GaN on foreign substrates has been hindered thus far by the formation of high densities of basal stacking faults (BSFs) and threading dislocations (TDs) during the growth process 9 , 10 . The anisotropic properties of nonpolar GaN have become the main challenge in growing a -plane GaN.…”

Section: Introductionmentioning

confidence: 99%

Impact of sandwiched strain periodic multilayer AlN/GaN on strain and crystalline quality of a-plane GaN

Kamarundzaman

Shuhaimi

Azman

et al. 2021

Sci Rep

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We demonstrated high-quality single crystalline a-plane undoped-gallium nitride grown on a nonpatterned r-plane sapphire substrate via metal–organic chemical vapor deposition. The effect of four different numbers of sandwiched strain-periodic AlN/GaN multilayers on the strain state, crystal quality, optical and electrical properties was investigated. Field emission scanning electron microscopy and atomic force microscopy showed that the surface morphology was improved upon insertion of 120 pairs of AlN/GaN thin layers with a root-mean-square roughness of 2.15 nm. On-axis X-ray ω-scan rocking curves showed enhanced crystalline quality: the full width at half maximum decreased from 1224 to 756 arcsec along the [0001] direction and from 2628 to 1360 arcsec along the [1–100] direction for a-GaN grown with 120 pairs of AlN/GaN compared to a-GaN without AlN/GaN pairs. Reciprocal space mapping showed that a-plane GaN with a high number of AlN/GaN pairs exhibits near-relaxation strain states. Room-temperature photoluminescence spectra showed that the sample with the highest number of AlN/GaN pairs exhibited the lowest-intensity yellow and blue luminescence bands, indicating a reduction in defects and dislocations. The a-plane InGaN/GaN LEDs with 120 pairs of SSPM-L AlN/GaN exhibited a significant increase (~ 250%) in light output power compared to that of LEDs without SSPM-L AlN/GaN pairs.

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Annealing of the sputtered AlN buffer layer on r‐plane sapphire and its effect on a‐plane GaN crystalline quality

Jinno

Otsuki

Niimi

et al. 2017

Physica Status Solidi (b)

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We demonstrated how annealing of the sputtered AlN buffer layer (sp‐AlN) on r‐plane sapphire could be used to produce a high‐crystalline‐quality a‐plane GaN (a‐GaN). The sp‐AlN with large grains was confirmed by annealing at 1600 °C in N2 ambient, consequently its crystalline orientation and quality were significantly improved. Moreover, it was found that a‐GaN grown on annealed sp‐AlN showed better crystalline quality, including a reduction of basal stacking fault density, than a‐GaN grown on untreated sp‐AlN (as sputtered). The implication is that the a‐GaN growth method using annealed sp‐AlN is an effective way to obtain high crystalline quality.

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Effect of Basal-plane Stacking Faults on X-ray Diffraction of Non-polar (1120) a-plane GaN Films Grown on (1102) r-plane Sapphire Substrates

Cited by 11 publications

References 29 publications

Highly Responsive, Self-Powered a-GaN Based UV-A Photodetectors Driven by Unintentional Asymmetrical Electrodes

Highly Responsive, Self-Powered a-GaN Based UV-A Photodetectors Driven by Unintentional Asymmetrical Electrodes

Impact of sandwiched strain periodic multilayer AlN/GaN on strain and crystalline quality of a-plane GaN

Annealing of the sputtered AlN buffer layer on r‐plane sapphire and its effect on a‐plane GaN crystalline quality

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