TY - JOUR
T1 - Thermal stability for reflectance and specific contact resistance of Ni/Ag-based contacts on p-Type GaN
AU - Lin, Ray Ming
AU - Chou, Yi Lun
AU - Tseng, Wan Ching
AU - Tsai, Chia Lung
AU - Li, Jen Chih
AU - Wu, Meng Chyi
PY - 2009
Y1 - 2009
N2 - In this study, we investigated the thermal stability of Ni/Ag-based alloy contacts on p-type GaN. We observed the morphology of aggregated Ag for the Ni/Ag bilayer on p-type GaN after annealing it at 500°C in an O2 ambient. To improve the thermal stability, we deposited a Ni/Ag/Au trilayer onto p-type GaN. In this case, Ag aggregation was retarded after thermal annealing, and the specific contact resistance exhibited improved stability. Furthermore, because strong interdiffusion of the Au and Ag layers leads to poor reflectance, we added a diffusion barrier layer into the system; i.e., we deposited Ni/Ag/Ti/Au onto p-type GaN, with the Ti layer playing the role of the diffusion barrier. After annealing, the contact exhibited diminished Ag aggregation and a lower level of interdiffusion of the Au and Ag layers. We investigated the effect of the annealing time (at 500°C in an O2 ambient) on the properties of the Ni/Ag (1/150 nm), Ni/Ag/Au (1/150/150 nm), and Ni/Ag/Ti/Au (1/150/500/150 nm) layers, namely, their values of specific contact resistance, determined using a modified transmission line model, and reflectance at 465 nm. According to analyses by using scanning electron microscopy and secondary-ion mass spectrometry, we determined that the aggregation of Ag and the interdiffusion of Au and Ag within the Ni/Ag/Ti/Au construct were both minimized with the presence of the Ti layer, thereby improving the thermal stability of the contact on the p-type GaN.
AB - In this study, we investigated the thermal stability of Ni/Ag-based alloy contacts on p-type GaN. We observed the morphology of aggregated Ag for the Ni/Ag bilayer on p-type GaN after annealing it at 500°C in an O2 ambient. To improve the thermal stability, we deposited a Ni/Ag/Au trilayer onto p-type GaN. In this case, Ag aggregation was retarded after thermal annealing, and the specific contact resistance exhibited improved stability. Furthermore, because strong interdiffusion of the Au and Ag layers leads to poor reflectance, we added a diffusion barrier layer into the system; i.e., we deposited Ni/Ag/Ti/Au onto p-type GaN, with the Ti layer playing the role of the diffusion barrier. After annealing, the contact exhibited diminished Ag aggregation and a lower level of interdiffusion of the Au and Ag layers. We investigated the effect of the annealing time (at 500°C in an O2 ambient) on the properties of the Ni/Ag (1/150 nm), Ni/Ag/Au (1/150/150 nm), and Ni/Ag/Ti/Au (1/150/500/150 nm) layers, namely, their values of specific contact resistance, determined using a modified transmission line model, and reflectance at 465 nm. According to analyses by using scanning electron microscopy and secondary-ion mass spectrometry, we determined that the aggregation of Ag and the interdiffusion of Au and Ag within the Ni/Ag/Ti/Au construct were both minimized with the presence of the Ti layer, thereby improving the thermal stability of the contact on the p-type GaN.
UR - http://www.scopus.com/inward/record.url?scp=67651230707&partnerID=8YFLogxK
U2 - 10.1149/1.3152593
DO - 10.1149/1.3152593
M3 - 文章
AN - SCOPUS:67651230707
SN - 1099-0062
VL - 12
SP - H315-H318
JO - Electrochemical and Solid-State Letters
JF - Electrochemical and Solid-State Letters
IS - 9
ER -