In situ stress measurements during MOCVD growth of thick N-polar InGaN

Zakaria Y. Al Balushi1 and Joan M. Redwing1,2

1Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA2Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, USA

Supplementary information:

Supplementary Figure S1. Low magnification Nomarski DIC optical micrographs of the

surface of III-polar InGaN (a), and N-polar InGaN (b).

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Supplementary Figure S2. Low magnification scanning electron micrographs (SEM) of the

surface of III-polar InGaN that exhibit a high density of V-pits (a), and N-polar InGaN that is

free of hexagonal hillocks (b).

Supplementary Figure S3. Energy dispersive x-ray (EDX) line scans from cross-section

specimens of III-polar and N-polar InGaN films using a SuperX EDX detector at 300 kV in a

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FEI Titan transmission electron microscope, revealing higher indium incorporation in N-polar

InGaN.

Supplementary Figure S4. (a-c) Additional TEM analysis of the III-polar InGaN (a-b) and N-

polar InGaN (c) dislocation microstructure using weak beam dark field mode. (Color online).

Supplementary Figure S5. Stacked overall curvature data (a) and stress-thickness versus

thickness curves (b) highlighting the incremental stress in the N-polar InGaN on different N-

polar GaN base layers, where the initial low temperature (LT) N-polar GaN layers in the two-

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step temperature growth varied in growth temperature (875°C top-green, 900°C middle-blue and

925°C bottom-red). Note: the vertical curvature axis in (a) are in 0.5 m -1 increments. (Color

online)

Incremental stress of N-polar GaN base layer (GPa)

Incremental stress of N-polar InGaN (GPa)

N-polar InGaN peak position (nm)

A B

+ 0.21 - 6.10 ~ 434.61 ~ 454.08

+ 0.04 - 6.37 ~ 431.32 ~ 452.93

- 0.04 - 6.82 ~ 428.02 ~ 443.02

Supplementary Table S1. PL peak positions of N-polar InGaN with corresponding constant

incremental stress values of N-polar InGaN and the N-polar GaN base layers.

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