Structural properties of GaN grown on AlGaN/AlN stress mitigating layers on 100-mm Si (111) by ammonia molecular beam epitaxy

The behavior of dislocations in a GaN layer grown on a 4-inch Si(111) substrate with an AlGaN/AlN strained layer superlattice using horizontal metal-organic chemical vapor deposition was observed by transmission electron microscopy. Cross-sectional observation indicated that a drastic decrease in the dislocation density occurred in the GaN layer. The reaction of a dislocation (b=1/3[-211-3]) and anothor dislocation (b =1/3[-2113]) to form one dislocation (b =2/3[-2110]) in the GaN layer was clarified by plan-view observation using weak-beam dark-field and large-angle convergent-beam diffraction methods.

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“…[14][15][16][17][18][19] As mentioned in Ref. 18, Burgers vector analysis is required to prove this.…”

Section: Introductionmentioning

confidence: 97%

Analysis of reaction between c+a and -c+a dislocations in GaN layer grown on 4-inch Si(111) substrate with AlGaN/AlN strained layer superlattice by transmission electron microscopy

et al. 2016

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“…The determination of (Q X , Q Z ) for a certain GaN layer is commonly done by combining measurements from two reflections, e.g., GaN (10-14) and (0002). 6 In the studied AlGaN/ GaN HEMT structure, we found (Q X , Q Z ) ¼ (3.6186, 7.7197) nm À1 for the GaN (10-14), which is obviously different from the relaxed point of (3.6208, 7.7138) nm À1 . In Fig.…”

mentioning

confidence: 80%

“…Therefore, the research community often uses GaN epilayers as the reference. [4][5][6] In our paper, we used the phrase "currently favored method" to refer to the method used by some researchers where the GaN epilayer is chosen as the reference with the implicit assumption that it is relaxed. This is typically exemplified in papers where XRD measurements of strain and alloy composition are reported based solely on 2h-x (or x-2h) curves or based on reciprocal space maps with no absolute referencing (either to a substrate or properly selfreferenced epilayers).…”

mentioning

confidence: 99%

Comment on “Determination of alloy composition and strain in multiple AlGaN buffer layers in GaN/Si system” [Appl. Phys. Lett. 105, 232113 (2014)]

Liu

Dolmanan

Bhat

et al. 2015

Applied Physics Letters

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In a recent letter, 1 Si (313) rather than was used as a reference to determine the alloy composition and the in-plane strain built in the AlGaN buffer layers of a GaNon-Si heterostructure via reciprocal space mapping (RSM) of the nitride (10-14) atomic planes. 1 The authors claimed that this method is more accurate than currently favored method which uses GaN as the reference. Unfortunately, the crystallographic tilt, i.e., the angle intrinsically formed between III-nitrides (0002) and Si (111), is unintentionally ignored by the authors. Another flaw is that the authors assume the GaN, as the reference in currently favored method, to be completely relaxed. As a result, the accuracy comparison made by the authors is misleading.Crystallographic tilt has been observed in various GaNon-Si heterostructures grown by metalorganic chemical vapor deposition (MOCVD) on either unintentionally or intentionally miscut Si (111) substrates. [2][3][4] The unintentionally miscut, particularly those of large-diameter Si wafers, is up to 0.5 . We found that such an unintentionally miscut could lead to a tilt of $0.2 between the GaN (0002) and Si (111) atomic planes, contributed by the Nagai tilt, misfit dislocations, and/ or dislocation bendings. 2 However, the crystal orientation of the III-nitride layers always follows that of the first nitride buffer immediately on the Si substrate. Obviously, the tilt between nitrides (0002) and Si (111) has different components towards the three 120 -rotated Si (313) planes. As a result, the nitrides (10-14) RSMs carried out in different azimuths (120 -rotated) using Si (313) as references would lead to different alloy compositions and/or strains. The worst case is that the tilt is right in one of the three 120 -rotated azimuths and the (10-14) RSM is happened to be carried out in this orientation. In this case, a tilt of 0.2 can cause a change of 0.029 Å to the lattice constant a of relaxed GaN, which leads to an inaccuracy of De a ¼ 0.92% in its in-plane strain measurement. This inaccuracy is even larger than the largest in-plane strain (typically that of AlN) of the nitride layers in GaN-on-Si. 1,5 To experimentally demonstrate the inaccuracy when using Si (313) as the reference, we have measured nitride (10-14) RSMs from an AlGaN/GaN high electron mobility transistor (HEMT) structure grown by MOCVD on an onaxis 200-mm diameter Si (111) wafer (miscut of 0.5 ). The nitride stack has the similar buffer structure as that measured in Ref. 1. The HRXRD system (Panalytical X'PERT PRO MRD XL) and its setup employed in this demonstration are also the same as those used in Ref. 1. We carried out the nitrides (10-14) RSM measurements in the three 120 -rotated azimuths using Si (313) atomic planes of the Si (111) substrate as the references. Figure 1(a) presents the (10-14) RSM results, and the reciprocal points in each set of the RSMs were collectively shifted, following Ref. 1, by locating Si (313) to (Q X , Q Z ) ¼ (3.0067, 7.4412) nm À1 . The Al compositions [Fig. 1(b)] and the in-plane strains ...

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“…have great potential for high frequency, high power, and high temperature applications because of their excellent material properties such as wide bandgap, high break down field, high saturation velocity, and high electron mobility. [1] The Al x Ga 1−x N thin films are extremely important materials with widespread applications for optoelectronic devices because they have a direct wide energy bandgap, which ranges from 6.2 to 3.4 eV. Due to their wide band gap range, the alloys are very attractive materials for applications in light emitting diodes, high electron mobility transistors, high density optical storage devices, [2,3] ultraviolet emitters and photodetectors.…”

Section: Introductionmentioning

confidence: 99%

Ni/Ag Schottky contacts on Al_0.11Ga_0.89N grown on Si (1 1 1) substrate by plasma-assisted MBE

Yusoff

Hassan

et al. 2015

Composite Interfaces

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Al 0.11 Ga 0.89 N/GaN samples are grown by plasma-assisted molecular beam epitaxy method on (1 1 1) silicon substrates. High purity gallium (7N) and aluminum (6N5) were used to grow Al 0.11 Ga 0.89 N, GaN, and AlN, respectively. The surface morphology, structural and optical properties of the sample has been investigated by scanning electron microscope (SEM), and high-resolution X-ray diffraction (HR-XRD), respectively. HR-XRD measurement showed that the sample has a typical diffraction pattern of hexagonal Al 0.11 Ga 0.89 N/GaN heterostructures. Ni/Ag bilayers are deposited on Al 0.11 Ga 0.89 N as the Schottky contacts. The effect of annealing in oxygen ambient on the electrical properties of Ni/Ag/Al 0.11 Ga 0.89 N is studied by currentvoltage measurement. The annealing at a temperature of 700°C for 10 min results in an increase in the ideality factor from 1.033 to 1.042 and an increase in the Schottky barrier height from 0.708 to 0.811 eV. Furthermore, the annealing in oxygen ambient also leads to an increase in the surface roughness of the contacts from 0.0098 to 0.1360 μm which is in agreement with the SEM results.

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Structural properties of GaN grown on AlGaN/AlN stress mitigating layers on 100-mm Si (111) by ammonia molecular beam epitaxy

Cited by 15 publications

References 24 publications

Analysis of reaction between c+a and -c+a dislocations in GaN layer grown on 4-inch Si(111) substrate with AlGaN/AlN strained layer superlattice by transmission electron microscopy

Analysis of reaction between c+a and -c+a dislocations in GaN layer grown on 4-inch Si(111) substrate with AlGaN/AlN strained layer superlattice by transmission electron microscopy

Comment on “Determination of alloy composition and strain in multiple AlGaN buffer layers in GaN/Si system” [Appl. Phys. Lett. 105, 232113 (2014)]

Ni/Ag Schottky contacts on Al_0.11Ga_0.89N grown on Si (1 1 1) substrate by plasma-assisted MBE

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Structural properties of GaN grown on AlGaN/AlN stress mitigating layers on 100-mm Si (111) by ammonia molecular beam epitaxy

Cited by 15 publications

References 24 publications

Analysis of reaction between c+a and -c+a dislocations in GaN layer grown on 4-inch Si(111) substrate with AlGaN/AlN strained layer superlattice by transmission electron microscopy

Analysis of reaction between c+a and -c+a dislocations in GaN layer grown on 4-inch Si(111) substrate with AlGaN/AlN strained layer superlattice by transmission electron microscopy

Comment on “Determination of alloy composition and strain in multiple AlGaN buffer layers in GaN/Si system” [Appl. Phys. Lett. 105, 232113 (2014)]

Ni/Ag Schottky contacts on Al0.11Ga0.89N grown on Si (1 1 1) substrate by plasma-assisted MBE

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Ni/Ag Schottky contacts on Al_0.11Ga_0.89N grown on Si (1 1 1) substrate by plasma-assisted MBE