Origins of hillock defects on GaN templates grown on Si(111)


Surface hillocks are observed on GaN-on-Si wafers with AlGaN and AlN layers.
Their origin has been identified by a combined use of FIB, TEM and XRD.
Ga-rich precipitates in the AlGaN layer are found underneath the hillocks.
Growth conditions to avoid their formation are suggested.


The origin of surface hillocks (also known as pancake defects) on GaN-on-Si wafers grown by MOVPE has been investigated. FIB/TEM observations confirmed that the appearance of the hillocks is due to the formation of Ga-rich precipitates within the AlGaN buffer layer. XRD (002) FWHM measurements also show that the surface hillocks are associated with a high degree of crystal tilt in the AlN nucleation layer. Two factors are considered to be the cause of such a phase separation: (1) a high density of surface steps associated with the regions of large crystal tilt which act as nucleation centers and (2) a lower mobility of Al adatoms at the growth surface compared with Ga, leading to a preferential incorporation of Ga in the precipitates. The impact of these precipitates on the wafer bow of the structures is considered.


  • A1. Characterization
  • A1. Defects
  • A1. X-ray diffraction
  • A3. Metalorganic vapor phase epitaxy
  • B1. Nitrides
  • B2. Semiconducting III–V materials
        • Source:Sciencedirect 

          If you find them interesting,please contact us: or visit our website:

No comments: