HVPE of GaN on Needle-shaped Seeds

Structural defects in these newly grown crystals have been studied by DSE in molten KOH-NaOH eutectics of both polar and nonpolar cross section samples sliced from the bulk material [14]. Current results of these studies can be summarized as follows  

In some cases, the array of dislocations converts into a misoriented parasitic grain. 

These and other etch figures are being calibrated 

The crystals described in this section were of n-type electrical conductivity with free electron concentration of about 5 x 10 cm . However, as it was shown by micro-Raman scattering measurements [18], at the interfaces 

For obtaining low defect densities larger bulk crystals by HVPE seeded with high-pressure needles, careful selection and preparation of seeds is necessary to avoid parasitic 3D nucleation on seed imperfections. It is shown that the HVPE growth on the needle-shaped seeds is a very stable process. Therefore, it seems that there are no physical obstacles for growing much larger crystals by this method. 

---