Effects of the AlN nucleation layer thickness on the crystal structures of an AlN epilayer grown on the 6H-SiC substrate


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Arslan E., Ozturk M. K. , Ozcelik S. , ÖZBAY E.

Philosophical Magazine, cilt.99, sa.14, ss.1715-1731, 2019 (SCI Expanded İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 99 Konu: 14
  • Basım Tarihi: 2019
  • Doi Numarası: 10.1080/14786435.2019.1600757
  • Dergi Adı: Philosophical Magazine
  • Sayfa Sayıları: ss.1715-1731

Özet

© 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group.The influence of the LT-AlN(NL) growth times on the mosaic structure parameters of the AlN layer grown on the LT-AlN(NL)/6H-SiC structures as well as the dislocation densities and the strain behaviours in the AlN epilayers has been investigated using XRD measurements. The growth times of the LT-AlN(NL) were changed to 0, 60, 120, 180, and 240 s. We observed that the mosaic structure parameters of the AlN epilayers were slightly affected by the LT-AlN(NL) growth times. However, the dislocation densities in the AlN layer are affected by the growth times of the LT-AlN(NL) layer. The highest edge dislocation density (5.48 × 1010 ± 2.3 × 109 cm−2) was measured for the sample in which 120 s grown LT-AlN(NL) was used. On the other hand, highest screw type dislocation density (1.21 × 1010 ± 1.7 × 109 cm−2) measured in the sample E that contains 240 s growth LT-AlN(NL). The strain calculation results show that the samples without LT-AlN(NL) suffered maximum compressive in-plane strain (−10.9 × 10−3 ± 1.8 × 10−4), which can be suppressed by increasing the LT-AlN(NL) growth times. The out-of-plane strain also has a compressive character and its values increase with LT-AlN(NL) growth times between 60 and 180 s. Same out-of-plane strain values were measured for the LT-AlN(NL) growth times of 180 and 240 s. Furthermore, the form of the biaxial stress in the AlN epilayer changed from compressive to tensile when the LT-AlN(NL) growth times were greater than 120 s.