Regrowth of GaN buffer layer on nanoporous GaN at chamber temperatures of

750, 850 and 1000C were used to study the mechanism behind threading

dislocations reduction in the GaN film subsequently overgrown. The growth of a

100nm GaN buffer layer at 850C causes dislocations to bend into the underlying

GaN and annihilated at the interface of GaN buffer/nanoporous GaN. Thermal

treatment of nanoporous GaN in MOCVD growth chamber at 850 C in NH3 and N2

ambient leads to the pinning of the threading dislocations at its surface edge steps

by impurity -vacancy complexes of SiNx. The SiNx were formed by the impinging

adatoms of NH3 which interact with Si dangling bonds at the sub-grain boundaries

of the nanoporous Si-doped GaN. When the nanoporous GaN sample undergoes

rapid thermal annealing in N2 ambient, no effective filling of these voids were

observed and dislocations density was not substantial reduced. Regrowth of GaN at

850 C re-structured the nanoporous GaN, forming a SiNx complex at the voids or

pores which pinned dislocation propagation. This explained the mechanism behind

dislocation annihilation in regrown GaN on nanoporous GaN template with the use

of additional interfacial GaN buffer layer.

Threading Dislocations Annihilation in Regrown GaN Film on Nanoporous GaN

Template. C.B.Soh, H.Hartono, S.Y.Chow, S.J.Chua, S.Tripathy: Physica Status

Solidi), 2009, 6[S2], S699-702