Investigations on V-defects in quaternary AlInGaN epilayers

Liu, J. P.; Wang, Y. T.; Yang, Hui; Jiang, Desheng; Jahn, U.; Ploog, K.

doi:10.1063/1.1767959

Cited by 53 publications

(43 citation statements)

References 21 publications

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“…The pit apex of V-defects is often connected with a threading dislocation line. The monochromatic CL image taken at the energy gap of AlInGaN epilayer samples exhibits dark spots surrounded by a bright rim at the location of V-defects [20]. The CL contrast was influenced by the In composition fluctuation in alloy and hence a shift of the CL peak wavelength.…”

Section: Featurementioning

confidence: 99%

Optical analysis of dislocation‐related physical processes in GaN‐based epilayers

Jiang

Zhao

Yang

2007

Physica Status Solidi (b)

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In this paper, recent progresses in optical analysis of dislocation-related physical properties in GaN-based epilayers are surveyed with a brief review. The influence of dislocations on both near-band edge emission and yellow luminescence (YL) is examined either in a statistical way as a function of dislocation density or focused on individual dislocation lines with a high spatial resolution. Threading dislocations may introduce non-radiative recombination centers and enhance YL, but their effects are affected by the structural and chemical environment. The minority carrier diffusion length may be dependent on either dislocation density or impurity doping as confirmed by the result of photovoltaic spectra. The in situ optical monitoring of the strain evolution process is employed during GaN heteroepitaxy using an AlN interlayer. A typical transition of strain from compression to tension is observed and its correlation with the reduction and inclination of threading dislocation lines is revealed.

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Section: Featurementioning

confidence: 99%

Optical analysis of dislocation‐related physical processes in GaN‐based epilayers

Jiang

Zhao

Yang

2007

Physica Status Solidi (b)

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“…28 Liu et al show that In segregation in AlInGaN is responsible for V-defect formation and increased indium content leads to increased V-defect density. 18 Recent work by Florescu et al 19 and Ting et al 20 shows that V-defect formation in InGaN/GaN MQW structures may be caused by a combination of effects due to barrier growth temperature and the formation of In-rich regions within the quantum well under specific growth conditions.…”

Section: Introductionmentioning

confidence: 98%

“…13,14 In addition, this In segregation on particular crystallographic planes leads to the formation of microstructural defects such as V defects (pinholes). [15][16][17][18][19][20] The V-defect formation is commonly observed in InGaN/GaN heterostructures. A V defect is an open hexagonal, inverted pyramid with six {101 -1} planes and a base on the (0001) c plane.…”

Section: Introductionmentioning

confidence: 99%

Investigation of microstructure and V-defect formation in InxGa1−xN/GaN MQW grown using temperature-gradient metalorganic chemical vapor deposition

Johnson

Liliental‐Weber

Zakharov

et al. 2005

J. Electron. Mater.

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Temperature-gradient metalorganic chemical vapor deposition (MOCVD) was used to deposit In x Ga 1-x N/GaN multiple quantum well (MQW) structures with a concentration gradient of indium across the wafer. These MQW structures were deposited on low defect density (2 ϫ 10 8 cm Ϫ2 ) GaN template layers for investigation of microstructural properties and V-defect (pinhole) formation. Room temperature (RT) photoluminescence (PL) and photomodulated transmission (PT) were used for optical characterization, which show a systematic decrease in emission energy for a decrease in growth temperature. Triple-axis x-ray diffraction (XRD), scanning electron microscopy, and cross-sectional transmission electron microscopy were used to obtain microstructural properties of different regions across the wafer. Results show that there is a decrease in crystal quality and an increase in V-defect formation with increasing indium concentration. A direct correlation was found between V-defect density and growth temperature due to increased strain and indium segregation for increasing indium concentration.

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“…While p-InGaN hole injection and contact layers are beneficial for the improvement of luminescence and electrical forward bias characteristics, the InGaN layer often shows, depending on thickness and composition of InGaN, a surface morphology with a high density of pits related to the formation of V-defects (also called inverted hexagonal pyramids), which have been proven to be associated with threading dislocations at their apexes. [9][10][11][12][13] It has been suggested that these pits act as a path for reverse leakage current. 14 In this study, in order to improve the surface morphology and electrical properties of the green LEDs, we developed an InGaN:Mg/GaN:Mg shortperiod superlattice (SPSL) to be used for p-type hole injection and contact layers.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Green Light-Emitting Diodes Using an InGaN:Mg/GaN:Mg Superlattice as p-Type Hole Injection and Contact Layers

Liu

Limb

Ryou

et al. 2007

Journal of Elec Materi

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Mg-doped InGaN/GaN p-type short-period superlattices (SPSLs) are developed for hole injection and contact layers of green light-emitting diodes (LEDs). V-defect-related pits, which are commonly found in an InGaN bulk layer, can be eliminated in an InGaN/GaN superlattice with thickness and average composition comparable to those of the bulk InGaN layer. Mg-doped InGaN/GaN SPSLs show significantly improved electrical properties with resistivity as low as $0.35 ohm-cm, which is lower than that of GaN:Mg and InGaN:Mg bulk layers grown under optimized growth conditions. Green LEDs employing Mg-doped InGaN/GaN SPSLs for hole injection and contact layers have significantly lower reverse leakage current, which is considered to be attributed to improved surface morphology. The peak electroluminescence intensity of LEDs with a SPSL is compared to that with InGaN:Mg bulk hole injection and contact layers.

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Investigations on V-defects in quaternary AlInGaN epilayers

Cited by 53 publications

References 21 publications

Optical analysis of dislocation‐related physical processes in GaN‐based epilayers

Optical analysis of dislocation‐related physical processes in GaN‐based epilayers

Investigation of microstructure and V-defect formation in InxGa1−xN/GaN MQW grown using temperature-gradient metalorganic chemical vapor deposition

Characteristics of Green Light-Emitting Diodes Using an InGaN:Mg/GaN:Mg Superlattice as p-Type Hole Injection and Contact Layers

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