Critical thickness for GaN thin film on AlN substrate

Coppeta, Raffaele; Ceric, H.; Holec, David

doi:10.1109/iirw.2013.6804177

Cited by 6 publications

(3 citation statements)

References 9 publications

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“…To the extent of our knowledge, this is the first systematic investigation of interfacial energetics as a function of the QW thickness. It completes previous works from the literature focusing on how the last influences strain partition and related electronic properties of such superlattices [16,17,20,25,27].…”

Section: Introductionsupporting

confidence: 69%

“…Superlattices are essential in manufacturing devices, e.g., optoelectronic, and present electronic properties highly conditioned by the strain partitioning in the superlattice. Above a critical layer thickness, the elastic energy stored therein is lowered via the spontaneous formation of interfacial misfit-dislocations [10][11][12][13][14][15][16][17][18]. It has been shown that the energy gaps of superlattices differ from those reached by alloyed constituents, which offer a means for bandgap tuning [19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

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Energetics of Interfaces and Strain Partition in GaN/AlN Pseudomorphic Superlattices

Karakostas,

Komninou,

Pontikis

2023

Crystals

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We present the results of a twofold experimental and computational study of (0001) GaN/AlN multilayers forming pseudomorphic superlattices. High-Resolution Transmission Electron Microscopy (HRTEM) shows that heterostructures with four c-lattice parameters thick GaN Quantum Wells (QW) are misfit-dislocation free. Accurate structural data are extracted from HRTEM images via a new methodology optimizing the residual elastic energy stored in the samples. Total energy calculations are performed with several models analogous to the experimental QWs with increasing thicknesses of GaN, whereas this of the AlN barrier is kept fixed at n = 8 c-lattice parameters. With vanishing external stresses, minimum energy configurations of the studied systems correspond to different strain states. Linear elasticity accurately yields the corresponding lattice parameters, suppressing the need for on-purpose total energy calculations. Theoretically justified parabolic fits of the excess interfacial energy yield the values of interfacial stress and elastic stiffness as functions of the GaN QW thickness. Total species-projected densities of states and gap values extracted from there allow deciphering the effect of the evolving strain on the electronic structure of the superlattice. It is found that the gap energy decreases linearly with increasing the strain of the QW. These results are briefly discussed in the light shed by previous works from the literature.

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Section: Introductionsupporting

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Energetics of Interfaces and Strain Partition in GaN/AlN Pseudomorphic Superlattices

Karakostas,

Komninou,

Pontikis

2023

Crystals

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“…The nominal HIL thicknesses for LED-A and LED-B were 200 nm and 20 nm, respectively. The critical thickness for the p-Al 0.53 Ga 0.47 N HIL on the Al 0.8 Ga 0.2 N EBL is estimated to be several dozen nanometers [33]. Therefore, we predict that the strain of the p-AlGaN HIL was relaxed completely in LED-A, but partly or completely remained in LED-B.…”

Section: Simulations and Experimentsmentioning

confidence: 85%

Enhancement of current injection efficiency of AlGaN-based deep-ultraviolet light-emitting diodes by controlling strain relaxation

Hao

Taniguchi

Inoue

2020

J. Phys. D: Appl. Phys.

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The external quantum efficiency (EQE) in electrically injected AlGaN-based deep-ultraviolet light-emitting diodes (DUV-LEDs) is severely limited by their poor current injection efficiency (CIE). We report improvement in the CIE via controlling the relaxation of strains in the p-AlGaN hole injection layer (HIL) and the electron blocking layer (EBL). Simulation results show that an unrelaxed strain in the HIL associated with a relaxed strain in EBL can significantly enhance CIE. Deeper analysis indicates that high hole concentrations can be generated at HIL/EBL interface by strain-induced piezoelectric fields, which can then provide abundant numbers of holes for injection into quantum wells. Two sub-280 nm DUV-LEDs were fabricated with specific designs for different strain relaxations in the p-AlGaN HIL by changing the HIL thickness from 200 to 20 nm. The strain difference was identified using Raman spectroscopy. Electroluminescence measurements demonstrated much higher EQE in the strained-HIL DUV-LEDs. By separating the EQE contributions of three efficiencies, i.e. the CIE, the radiative recombination efficiency and the light extraction efficiency, we found that the EQE enhancement could mainly be attributed to the improved CIE, which agreed well with the simulation results.

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In Al1–N/Al0.53Ga0.47N multiple quantum wells on Al0.5Ga0.5N buffer with variable in-plane lattice parameter

Zubialevich

Rzheutski

et al. 2018

Journal of Luminescence

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Critical thickness for GaN thin film on AlN substrate

Cited by 6 publications

References 9 publications

Energetics of Interfaces and Strain Partition in GaN/AlN Pseudomorphic Superlattices

Energetics of Interfaces and Strain Partition in GaN/AlN Pseudomorphic Superlattices

Enhancement of current injection efficiency of AlGaN-based deep-ultraviolet light-emitting diodes by controlling strain relaxation

In Al1–N/Al0.53Ga0.47N multiple quantum wells on Al0.5Ga0.5N buffer with variable in-plane lattice parameter

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