The effects of two-stage HT-GaN growth with different V/III ratios during 3D-2D transition

ALTUNTAŞ İ., DEMİR İ., KASAPOĞLU A. E., Mobtakeri S., GÜR E., Elagoz S.

JOURNAL OF PHYSICS D-APPLIED PHYSICS, vol.51, no.3, 2018 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 51 Issue: 3
  • Publication Date: 2018
  • Doi Number: 10.1088/1361-6463/aa9bd6
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Keywords: GaN growth, MOCVD, V/III ratio, edge dislocation, screw dislocation, DEFECT STRUCTURE, BUFFER LAYERS, LASER-DIODES, IN-SITU, INGAN, NUCLEATION, TEMPERATURE, FILMS, BLUE
  • Eskisehir Osmangazi University Affiliated: No


The aim of the study is to understand the effects of two stages of HT-GaN growth with different V/III ratios on optical, chemical and structural characteristics of the HT-GaN layer. In addition, the effects of two-stage growth on the transport properties has been presented through fabricated Schottky diodes. As the V/III ratio in the 1st stage growth of HT-GaN layer is varied, it has been observed that recovery of reflectance is faster with higher V/III ratios, while no significant effect has been observed by changing the V/III ratios in the 2nd stage of HT-GaN growth. The 2nd stage growth is caused to decrease in screw dislocation densities obtained from the high-resolution x-ray diffraction measurements. The lowest edge type dislocation densities have been obtained for samples with lower V/III ratios in both the 1st and 2nd stages of HT-GaN growth. Well-defined terraces and a few GaN atomic layer surface roughness have been realized through the atomic force microscopy measurements on all the samples. Ga atom bound oxygen states has been investigated through the x-ray photoelectron spectroscopy to find out the V/III ratio effect on the impurity incorporation. An increase in the V/III ratio has given rise to a higher percentage of oxygen incorporation during the 2nd stage of growth. The lowest internal quantum efficiency has been obtained for the samples grown at the highest V/III ratio for both the 1st and 2nd growth stages. Fine excitonic transitions have been indicated by the low temperature high-resolution photoluminescence measurements. Current-voltage measurements performed on the Schottky diodes have shown the effects on the diode parameters.