TY - JOUR
T1 - Effect of Ga dissolution in Au of Ni-Au system on ohmic contact formation to p-type GaN
AU - Yang, Jiin Long
AU - Chen, J. S.
N1 - Funding Information:
The authors gratefully acknowledge the financial support from the National Science Council of Taiwan, R.O.C. (grant No. 90-2216-E-006-069). The authors also thank the supports of the TEM facility at National Sun Yat-sen University and XPS system (VG Microlab 250) at National Taiwan University.
PY - 2006/8/10
Y1 - 2006/8/10
N2 - The effect of Ga dissolution in Au of Ni-Au system on ohmic contact formation to p-type GaN was carried out in this study. The Au (8 - x nm)/Ni (2 nm)/Au(x nm) deposited on p-GaN by magnetron sputtering system, where x = 0, 2, 4, and 6. It was discovered that after annealing in O2 ambient, the samples show ohmic characteristic when x is equal to 4 and 6. The TEM cross-sectional observation indicated that Ni did not diffuse to the GaN surface during annealing and the Ni transformed to NiO at the same time. The final microstructure became Au(8 - x)/NiO/Au(x)/p-GaN, where Au(8 - x) layer agglomerated into the semi-continuous and NiO was considered a barrier to prevent the diffusion of Ga atoms. Therefore, the presence of Au(x) plays a role to dissolve the Ga atoms from p-GaN, leaving Ga vacancies below the contact, thus increased the hole concentration of p-GaN. It is concluded that amount of Au(x) contacting to p-GaN is a key to achieve ohmic characteristics on p-GaN in this study.
AB - The effect of Ga dissolution in Au of Ni-Au system on ohmic contact formation to p-type GaN was carried out in this study. The Au (8 - x nm)/Ni (2 nm)/Au(x nm) deposited on p-GaN by magnetron sputtering system, where x = 0, 2, 4, and 6. It was discovered that after annealing in O2 ambient, the samples show ohmic characteristic when x is equal to 4 and 6. The TEM cross-sectional observation indicated that Ni did not diffuse to the GaN surface during annealing and the Ni transformed to NiO at the same time. The final microstructure became Au(8 - x)/NiO/Au(x)/p-GaN, where Au(8 - x) layer agglomerated into the semi-continuous and NiO was considered a barrier to prevent the diffusion of Ga atoms. Therefore, the presence of Au(x) plays a role to dissolve the Ga atoms from p-GaN, leaving Ga vacancies below the contact, thus increased the hole concentration of p-GaN. It is concluded that amount of Au(x) contacting to p-GaN is a key to achieve ohmic characteristics on p-GaN in this study.
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U2 - 10.1016/j.jallcom.2005.09.075
DO - 10.1016/j.jallcom.2005.09.075
M3 - Article
AN - SCOPUS:33745264403
SN - 0925-8388
VL - 419
SP - 312
EP - 318
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
IS - 1-2
ER -