Characterization of free-standing Hydride Vapor Phase Epitaxy GaN

A free-standing GaN template grown by hydride vapor phase epitaxy has been characterized by transmission electron microscopy ~TEM!. The TEM investigation was augmented by x-ray diffraction, defect delineation etching process followed by imaging with atomic force microscopy and variable temperature photoluminescence. The density of dislocations near the N face was determined to be, in order, 3613107, 4613107, and about 13107 cm22 by cross-sectional TEM, plan-view TEM, and a defect revealing etch, respectively. The same methods on the Ga face revealed the defect concentration to be, in order, less than 13107 cm22 by plan-view TEM, less than 53106 cm22 by cross-sectional TEM, and 53105 cm22 by defect revealing hot H3PO4 acid, respectively. The full width at half maximum of the symmetric ~0002! x-ray diffraction peak was 69 and 160 arc sec for the Ga and N faces, respectively. That for the asymmetric (101I4) peak was 103 and 140 arc sec for Ga and N faces, respectively. The donor bound exciton linewidth was about 1meV each at 10 K, and a green band centered at about 2.44 eV was observed.