Improvements in (112̅2) semipolar GaN crystal quality by graded superlattices

Xu, Shengrui; Zhang, J.C.; Cao, Yanrong; Zhou, Xiaowei; Xue, JunShuai; Lin, Zhiyu; Ma, Jinbang; Bao, Feng; Hao, Yue

doi:10.1016/j.tsf.2011.09.049

Cited by 16 publications

(13 citation statements)

References 24 publications

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“…The decrease in striation density indicates the reduction of the BSF density in sample "B2". 18,20 Fig . 8a shows the XRD ω-2θ scans of samples "A2" and "B2".…”

Section: Resultsmentioning

confidence: 99%

In situ asymmetric island sidewall growth of high-quality semipolar (112̄2) GaN on m-plane sapphire

Shen

Liu

et al. 2016

CrystEngComm

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In situ asymmetric island sidewall growth (AISG) was developed to enhance Ga-face facet growth and improve the crystalline quality of (1122) GaN epilayers on m-plane sapphire substrates. In the early growth stage island shaping and sidewall faceting were distinct and controlled by growth design. Using in situ AISG, {0002} instead of {1103} sidewall facets were formed on the Ga-rich island surface, which eliminated formation of a {1103} phase during subsequent layer growth of semipolar GaN. Enhanced Ga-face sidewall facet growth led to +c regions overlapping −c regions, which reduced defect density. Pure semipolar (1122) epilayers with a reduced surface striation density and a basal-plane stacking fault density of 8 × 10 3 cm −1 were obtained. The observation of a narrow E H 2 peak and an intense E 1 (LO) peak in Raman spectra indicates that almost strain-free high-quality semipolar (1122) GaN films were achieved. The photoluminescence emission intensity from the (1122) GaN film prepared by in situ AISG was dominated by band-edge emission and enhanced ∼4 times more than that from conventional (1122) GaN.

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“…The decrease in striation density indicates the reduction of the BSF density in sample "B2". 18,20 Fig . 8a shows the XRD ω-2θ scans of samples "A2" and "B2".…”

Section: Resultsmentioning

confidence: 99%

In situ asymmetric island sidewall growth of high-quality semipolar (112̄2) GaN on m-plane sapphire

Shen

Liu

et al. 2016

CrystEngComm

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“…15,31 It should be noted that the (n0-n0) plane XRCs are greatly influenced by the BSFs, while the (000n) plane XRCs are correlated with the partial dislocations and/or perfect dislocations. 20,28,29,32 The (n0-n0) series measurement in Figure 1c suggests that the density of the BSFs type I 1 (in conjunction with (10−10) plane XRC) and I 2 (in conjunction with (20−20) plane XRC) is receded as the AlN/GaN period was increased. This might be because the increase in the ML period would further facilitate the reduction of the BSFs.…”

Section: ■ Results and Discussionmentioning

confidence: 94%

“…Studies have shown that the typical undulated features of semipolar GaN is well correlated to the defect propagations. 24,32 It is presumed that the higher density of the undulations is a consequence of higher defect density propagating throughout the epilayer. 24 In order to further clarify the origins of the undulations, higher magnification of the surface was conducted with the scan size of 500 × 500 nm.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Impact of a Strained Periodic Multilayer on the Surface and Crystal Quality of a Semipolar (11–22) GaN Template

Makinudin

Omar

Anuar

et al. 2019

Crystal Growth & Design

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Efficient reduction of defects and dislocations in a semipolar (11− 22) GaN epilayer with the use of an AlN/GaN strained periodic multilayer is demonstrated. On-and off-axis X-ray rocking curve analyses have shown significant improvement in the crystalline qualities with remarkable narrowing in their respective full width at half-maximum upon utilization of increased AlN/GaN pairs. X-ray reciprocal space mapping revealed a prominent increment in the degree of relaxation state, with notable shrinkage in the diffuse scattering streak. Structural evaluation via transmission electron microscopey illuminates the interruption of defect and dislocation propagation due to the strained periodic multilayers. It was observed that the first 20th pairs exhibited a three-dimensional growth mode owning to numerous defects originating from the AlN/sapphire interface. Such a phenomenon was found to have a positive impact toward accumulating the propagation of defects. The surface morphology analysis elucidates the reduced stripe-like undulations, whereby the terrace-like features in the lower scales endured an enhanced rearrangement favoring the reduced defect density.

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“…In fact, the use of superlattice interlayer in buffer layer to modify the dislocation of GaN epitaxy and the introduction of thick graded AlGaN buffer layer into growth of GaN films to reduce the large lattice mismatch between GaN and Si (111) substrates take advantage of the strain management for the dislocation inclination and annihilation. 16,17,[32][33][34] In summary, all these investigations reveal that the BHEI structure is a promising method to guarantee the stable operation in future device application for the GaN terahertz Gunn diodes.…”

Section: Discussionmentioning

confidence: 90%

Dislocation blocking by AlGaN hot electron injecting layer in the epitaxial growth of GaN terahertz Gunn diode

Yang

Zhang

et al. 2013

Journal of Applied Physics

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This paper reports an efficient method to improve the crystal quality of GaN Gunn diode with AlGaN hot electron injecting layer (HEI). An evident reduction of screw dislocation and edge dislocation densities is achieved by the strain management and the enhanced lateral growth in high temperature grown AlGaN HEI layer. Compared with the top hot electron injecting layer (THEI) structure, the bottom hot electron injecting layer (BHEI) structure enhances the crystal quality of transit region due to the growth sequence modulation of HEI layer. A high Hall mobility of 2934 cm2/Vs at 77 K, a nearly flat downtrend of Hall mobility at the temperature ranging from 300 to 573 K, a low intensity of ratio of yellow luminescence band to band edge emission, a narrow band edge emission line-width, and a smooth surface morphology are observed for the BHEI structural epitaxy of Gunn diode, which indicates that AlGaN BHEI structure is a promising candidate for fabrication of GaN Gunn diodes in terahertz regime.

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Improvements in (112̅2) semipolar GaN crystal quality by graded superlattices

Cited by 16 publications

References 24 publications

In situ asymmetric island sidewall growth of high-quality semipolar (112̄2) GaN on m-plane sapphire

In situ asymmetric island sidewall growth of high-quality semipolar (112̄2) GaN on m-plane sapphire

Impact of a Strained Periodic Multilayer on the Surface and Crystal Quality of a Semipolar (11–22) GaN Template

Dislocation blocking by AlGaN hot electron injecting layer in the epitaxial growth of GaN terahertz Gunn diode

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