TY - GEN
T1 - Defect investigation of GaN thin films etched by photo-electrochemical and hot wet etching by atomic force and transmission electron microscopy
AU - Visconti, P.
AU - Jones, K. M.
AU - Reshchikov, M. A.
AU - Cingolani, R.
AU - Morkoç, H.
AU - Molnar, R. J.
AU - Smith, David
PY - 2001
Y1 - 2001
N2 - The availability of reliable and quick methods to investigate defects in GaN films is of great interest. Photo-electrochemical (PEC), and hot wet etching using both H3PO4 acid and molten KOH have been used to study structural defects in GaN layers grown by hydride vapor phase epitaxy and molecular beam epitaxy. The purpose of this work is to determine whether, and under what conditions, these different methods of investigation are consistent and to get to a more accurate estimation of the defect density. As-grown and etched surfaces were investigated by atomic force microscopy (AFM), and plan-view and cross-sectional transmission electron microscopy (TEM). Free-standing whisker-like features and hexagonal etch pits were formed on the etched sample surfaces by PEC and wet etching, respectively. Using plan-view AFM, we found the density of whiskers (8×108-1 × 10 9 cm-2) to be similar to the etch pit densities when etched in both H3PO4 and molten KOH under precise etching conditions. During the wet etching process, a careful balance must be struck to ensure that every defect is delineated, but not overetched to cause merging which would lead to an underestimation of the defect density. Additionally, TEM observations confirmed the dislocation densities obtained by etching, which increased our confidence in the consistency of the methods used.
AB - The availability of reliable and quick methods to investigate defects in GaN films is of great interest. Photo-electrochemical (PEC), and hot wet etching using both H3PO4 acid and molten KOH have been used to study structural defects in GaN layers grown by hydride vapor phase epitaxy and molecular beam epitaxy. The purpose of this work is to determine whether, and under what conditions, these different methods of investigation are consistent and to get to a more accurate estimation of the defect density. As-grown and etched surfaces were investigated by atomic force microscopy (AFM), and plan-view and cross-sectional transmission electron microscopy (TEM). Free-standing whisker-like features and hexagonal etch pits were formed on the etched sample surfaces by PEC and wet etching, respectively. Using plan-view AFM, we found the density of whiskers (8×108-1 × 10 9 cm-2) to be similar to the etch pit densities when etched in both H3PO4 and molten KOH under precise etching conditions. During the wet etching process, a careful balance must be struck to ensure that every defect is delineated, but not overetched to cause merging which would lead to an underestimation of the defect density. Additionally, TEM observations confirmed the dislocation densities obtained by etching, which increased our confidence in the consistency of the methods used.
UR - http://www.scopus.com/inward/record.url?scp=34249911996&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=34249911996&partnerID=8YFLogxK
U2 - 10.1557/proc-680-e5.8
DO - 10.1557/proc-680-e5.8
M3 - Conference contribution
AN - SCOPUS:34249911996
SN - 1558996168
SN - 9781558996168
T3 - Materials Research Society Symposium Proceedings
SP - 162
EP - 167
BT - Wide-Bandgap Electronics
PB - Materials Research Society
T2 - 2001 MRS Spring Meeting
Y2 - 16 April 2001 through 20 April 2001
ER -