Optimizing GaN () hetero‐epitaxial templates grown on () sapphire

Pristovsek, Markus; Frentrup, Martin; Han, Yisong; Humphreys, C. J.

doi:10.1002/pssb.201552263

Cited by 19 publications

(20 citation statements)

References 32 publications

(77 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1(d) . Similar to the observation by SEM, the surface of (11–22) GaN layer exhibits “facet-like” features with a root mean square (RMS) roughness below 9 nm over 5 × 5 μm 2 surface area, which is comparable to previous reports 23 27 28 . The typical arrowhead-like surface morphology of semi-polar (11–22) GaN film was developed by using the heteroepitaxial growth.…”

Section: Resultssupporting

confidence: 88%

See 1 more Smart Citation

Anisotropic structural and optical properties of semi-polar (11–22) GaN grown on m-plane sapphire using double AlN buffer layers

Zhao

Wang

Yang

et al. 2016

Sci Rep

View full text Add to dashboard Cite

We report the anisotropic structural and optical properties of semi-polar (11–22) GaN grown on m-plane sapphire using a three-step growth method which consisted of a low temperature AlN buffer layer, followed by a high temperature AlN buffer layer and GaN growth. By introducing double AlN buffer layers, we substantially improve the crystal and optical qualities of semi-polar (11–22) GaN, and significantly reduce the density of stacking faults and dislocations. The high resolution x-ray diffraction measurement revealed that the in-plane anisotropic structural characteristics of GaN layer are azimuthal dependent. Transmission electron microscopy analysis showed that the majority of dislocations in the GaN epitaxial layer grown on m-sapphire are the mixed-type and the orientation of GaN layer was rotated 58.4° against the substrate. The room temperature photoluminescence (PL) spectra showed the PL intensity and wavelength have polarization dependence along parallel and perpendicular to the [1–100] axis (polarization degrees ~ 0.63). The realization of a high polarization semi-polar GaN would be useful to achieve III-nitride based lighting emission device for displays and backlighting.

show abstract

Section: Resultssupporting

confidence: 88%

“…Another challenge in heteroepitaxy of (11–22) III-nitrides on m-plane sapphire is (10-1-3) mixed phases. To reduce the contributions of unwanted (10-1-3)-oriented phases, a few methods for MOCVD growth of (11–22) III-nitrides have also been reported 20 21 22 23 . The common procedure of these methods is nucleation of AlN or AlN buffer layer.…”

mentioning

confidence: 99%

Anisotropic structural and optical properties of semi-polar (11–22) GaN grown on m-plane sapphire using double AlN buffer layers

Zhao

Wang

Yang

et al. 2016

Sci Rep

View full text Add to dashboard Cite

show abstract

“…This effect of SiH 4 has been deliberately used to reduce defects by inducing three dimensional growth. 11,19 A similar effect of SiH 4 was reported on the topography of (1120) GaN. 18 Overall, the incorporation of Si on (1122) behaves similarly to that on (1120).…”

Section: Doping and Contactsmentioning

confidence: 56%

Comparative study of (0001) and InGaN based light emitting diodes

Pristovsek

Humphreys

Bauer

et al. 2016

Jpn. J. Appl. Phys.

Self Cite

View full text Add to dashboard Cite

We have systematically investigated the doping of (1122) with Si and Mg by metal-organic vapour phase epitaxy for light emitting diodes (LEDs). By Si doping of GaN we reached electron concentrations close to 10 20 cm −3 , but the topography degrades above mid 10 19 cm −3. By Mg doping we reached hole concentrations close to 5×10 17 cm −3 , using Mg partial pressures about 3× higher than those for (0001). Exceeding the maximum Mg partial pressure led to a quick degradation of the sample. Low resistivities as well as high hole concentrations required a growth temperature of 900 • C or higher. At optimised conditions the electrical properties as well as the photoluminescence of (1122) p-GaN were similar to (0001) p-GaN. The best ohmic p-contacts were achieved by NiAg metallisation. A single quantum well LED emitting at 465 nm was realised on (0001) and (1122). Droop (sub-linear increase of the light output power) occurred at much higher current densities on (1122). However, the light output of the (0001) LED was higher than that of (1122) until deep in the droop regime. Our LEDs as well as those in the literature indicate a reduction in efficiency from (0001) over semi-polar to non-polar orientations. We propose that reduced fields open a loss channel for carriers.

show abstract

“…Dislocation reduction is realized through either a direct blocking by the SiN mask or through an annihilation among dislocations passing through the holes in the SiN mask. However, SiN on the semi-polar (11-22) plane has been reported to be not as effective as that on the a-and c-plane [4]. continue.…”

Section: Dislocation Reduction Using a Sin Interlayermentioning

confidence: 96%

Toward defect‐free semi‐polar GaN templates on pre‐structured sapphire

Han

Caliebe

Hage

et al. 2015

Physica Status Solidi (b)

Self Cite

View full text Add to dashboard Cite

The microstructure of semi‐polar (11–22) GaN templates grown on pre‐structured r‐plane sapphire by MOVPE has been characterized by TEM. Cross‐sectional observations indicate that defects are generated in three regions of the layers: threading dislocations at the inclined GaN/sapphire interface, basal plane stacking faults (BSFs) at the c−‐wing, BSFs and threading dislocations at the coalescence between neighboring GaN stripes. An in situ SiN interlayer deposited at an early stage of the growth is shown to be effective in blocking the propagation of dislocations, which is mainly attributed to SiN formed on the c‐plane rather than on the (11–22) plane. Si‐doped marker layers have been used to study the evolution of the growth front before coalescence as a function of temperature. A high growth temperature is associated with the formation of highly faceted GaN stripes. Dislocations originally running along the c‐direction are bent to the [11–20] direction driven by a progressing (11–22) facet. An efficient defect reduction is realized as a result of terminating these dislocations at voids partially defined by the (11–20) facet.

show abstract

Optimizing GaN () hetero‐epitaxial templates grown on () sapphire

Cited by 19 publications

References 32 publications

Anisotropic structural and optical properties of semi-polar (11–22) GaN grown on m-plane sapphire using double AlN buffer layers

Anisotropic structural and optical properties of semi-polar (11–22) GaN grown on m-plane sapphire using double AlN buffer layers

Comparative study of (0001) and InGaN based light emitting diodes

Toward defect‐free semi‐polar GaN templates on pre‐structured sapphire

Contact Info

Product

Resources

About