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, 3 +/- 1 X 10(7), 4 +/- 1 x 10(7), and about 1 X 10(7) cm(-2) 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 1 X 10(7) cm(-2) by plan-view TEM, less than 5 x 10(6) cm(-2) by cross-sectional TEM, and 5 X 10(5) cm(-2) 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 are sec for the Ga and N faces, respectively. That for the asymmetric (10(1) over bar4) peak was 103 and 140 are sec for Ga and N faces, respectively. The donor bound exciton linewidth was about 1 meV each at 10 K, and a green band centered at about 2.44 eV was observed. (C) 2001 American Institute of Physics.