Surface reconstructions of (0001) AlN during metal‐organic vapor phase epitaxy

Pristovsek, Markus; Bellman, Konrad; Mehnke, Frank; Stellmach, Joachim; Wernicke, Tim; Kneissl, Michael

doi:10.1002/pssb.201600711

Cited by 10 publications

(12 citation statements)

References 25 publications

(40 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Both the predicted and observed step behavior can depend upon the chemical environment (e.g., OMVPE vs. MBE) and how it passivates the step edges. For example, arguments regarding dangling bonds at steps 6 , 8 depend on the effects of very high or low V/III ratios 14 and the presence of NH 3 or H 2 . Likewise, KMC studies 16 – 19 typically make assumptions about bonding that determine the rates of atomic-scale processes at steps.…”

Section: Discussionmentioning

confidence: 99%

“…The alternating nature of the steps on such surfaces has been imaged in several systems, including SiC 4 , GaN 6 , 8 , 10 – 13 , AlN 14 , and ZnO 15 . These systems typically show a tendency for local pairing of steps (i.e., alternating step spacings), and an interlaced structure in which the step pairs switch partners at corners where their azimuth changes by 60°, as shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…The difference between the kinetics at A and B steps is a reflection of the chemical states of the adatoms, steps, and terraces that affect the dynamics of A and B steps. Studies of islands on the FCC Pt (111) surface 25 , 26 have found that A steps have a higher growth rate than B steps, but that this relationship is reversed by the presence of adsorbates such as CO. An experimental study of AlN (0001) surfaces grown by OMVPE 14 found a change in the terrace fraction as a function of the V/III ratio used during growth. Ab initio calculations of kinetic barriers on GaN and AlN (0001) under MBE and OMVPE conditions 20 – 22 found that the barriers and adsorption energies at A and B steps depend in detail on the surface reconstruction induced by the environment.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

In situ microbeam surface X-ray scattering reveals alternating step kinetics during crystal growth

Thompson

et al. 2021

Nat Commun

View full text Add to dashboard Cite

The stacking sequence of hexagonal close-packed and related crystals typically results in steps on vicinal {0001} surfaces that have alternating A and B structures with different growth kinetics. However, because it is difficult to experimentally identify which step has the A or B structure, it has not been possible to determine which has faster adatom attachment kinetics. Here we show that in situ microbeam surface X-ray scattering can determine whether A or B steps have faster kinetics under specific growth conditions. We demonstrate this for organo-metallic vapor phase epitaxy of (0001) GaN. X-ray measurements performed during growth find that the average width of terraces above A steps increases with growth rate, indicating that attachment rate constants are higher for A steps, in contrast to most predictions. Our results have direct implications for understanding the atomic-scale mechanisms of GaN growth and can be applied to a wide variety of related crystals.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

In situ microbeam surface X-ray scattering reveals alternating step kinetics during crystal growth

Thompson

et al. 2021

Nat Commun

View full text Add to dashboard Cite

show abstract

“…The quality of interfaces in GaN/AlN heterostructures obtained using various technologies is determined by many factors, including, first of all, the surface mobility of precursors (adatoms) and the rate of altering incorporation. This does not only depend on supply, but also involves surface processes, like metal overlayer [ 7 , 8 , 9 ]. Another important factor for the sharpness of heterointerfaces is the atomic segregation either to the surface of structures or to internal defects (threading dislocations).…”

Section: Introductionmentioning

confidence: 99%

The Effect of Interface Diffusion on Raman Spectra of Wurtzite Short-Period GaN/AlN Superlattices

et al. 2021

Self Cite

View full text Add to dashboard Cite

We present an extensive theoretical and experimental study to identify the effect on the Raman spectrum due to interface interdiffusion between GaN and AlN layers in short-period GaN/AlN superlattices (SLs). The Raman spectra for SLs with sharp interfaces and with different degree of interface diffusion are simulated by ab initio calculations and within the framework of the random-element isodisplacement model. The comparison of the results of theoretical calculations and experimental data obtained on PA MBE and MOVPE grown SLs, showed that the bands related to A1(LO) confined phonons are very sensitive to the degree of interface diffusion. As a result, a correlation between the Raman spectra in the range of A1(LO) confined phonons and the interface quality in SLs is obtained. This opens up new possibilities for the analysis of the structural characteristics of short-period GaN/AlN SLs using Raman spectroscopy.

show abstract

“…Images of {0001} surfaces showing the alternating nature of the steps have been obtained for several HCPrelated systems, including SiC [9][10][11] , GaN 7, [12][13][14][15][16][17][18][19] , AlN 20 , and ZnO 21 . As shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of Atomic Steps on GaN (0001) during Vapor Phase Epitaxy

Ju,

Xu,

Thompson

et al. 2020

Preprint

View full text Add to dashboard Cite

Images of the morphology of GaN (0001) surfaces often show half-unit-cell-height steps separating a sequence of terraces having alternating large and small widths. This can be explained by the αβαβ stacking sequence of the wurtzite crystal structure, which results in steps with alternating A and B edge structures for the lowest energy step azimuths, i.e. steps normal to [0110] type directions. Predicted differences in the adatom attachment kinetics at A and B steps would lead to alternating α and β terrace widths. However, because of the difficulty of experimentally identifying which step is A or B, it has not been possible to determine the absolute difference in their behavior, e.g. which step has higher adatom attachment rate constants. Here we show that surface X-ray scattering can measure the fraction of α and β terraces, and thus unambiguously differentiate the growth dynamics of A and B steps. We first present calculations of the intensity profiles of GaN crystal truncation rods (CTRs) that demonstrate a marked dependence on the α terrace fraction fα. We then present surface X-ray scattering measurements performed in situ during homoepitaxial growth on (0001) GaN by vapor phase epitaxy. By analyzing the shapes of the (101L) and (011L) CTRs, we determine that the steady-state fα increases at higher growth rate, indicating that attachment rate constants are higher at A steps than at B steps. We also observe the dynamics of fα after growth conditions are changed. The results are analyzed using a Burton-Cabrera-Frank model for a surface with alternating step types, to extract values for the kinetic parameters of A and B steps. These are compared with predictions for GaN (0001).

show abstract

Surface reconstructions of (0001) AlN during metal‐organic vapor phase epitaxy

Cited by 10 publications

References 25 publications

In situ microbeam surface X-ray scattering reveals alternating step kinetics during crystal growth

In situ microbeam surface X-ray scattering reveals alternating step kinetics during crystal growth

The Effect of Interface Diffusion on Raman Spectra of Wurtzite Short-Period GaN/AlN Superlattices

Dynamics of Atomic Steps on GaN (0001) during Vapor Phase Epitaxy

Contact Info

Product

Resources

About