TY - GEN
T1 - High temperature stable WSix ohmic contacts on GaN
AU - Pearton, S. J.
AU - Donovan, S. M.
AU - Abernathy, C. R.
AU - Ren, F.
AU - Zolper, J. C.
AU - Cole, M. W.
AU - Zeitouny, A.
AU - Eizenberg, M.
AU - Shul, R. J.
N1 - Publisher Copyright:
© 1998 IEEE.
PY - 1998
Y1 - 1998
N2 - We have sputter-deposited 500-1200 Å thick WSi0.45 metallization onto n+ GaN (n≥1019 cm-3) doped either during MOCVD growth or by direct Si+ ion implantation (5×1015 cm-2, 100 keV) activated by RTA at 1100°C for 30 secs. In the epi samples Rc values of ∼10-14 ω cm2 were obtained, and were stable to ∼1000°C. The annealing treatments up to 600°C had little effect on the WSix/GaN interface, but the beta/-W2N phase formed between 700-800°C, concomitant with a strong reduction (approximately a factor of 2) in near-surface crystalline defects in the GaN. Spiking of the metallization down the threading and misfit dislocations was observed at 800°C, extending >5000 Å in some cases. This can create junction shorting in bipolar or thyristor devices, Rc values of <10-6 ωcm2 were obtained on the implanted samples for 950°C annealing, with values of after 1050°C anneals. The lower Rc values compared to epi samples appear to be a result of the higher peak doping achieved, ∼5×1020 cm-3. We observed wide spreads in Rc values over a wafer surface, with the values on 950°C annealed material ranging from 10-7 to 10-4 ω cm2. There appear to be highly nonuniform doping regions in the GaN, perhaps associated with the high defect density (1010 cm-2) in heteroepitaxial material, and this may contribute to the variations observed. We also believe that near-surface stoichiometry is variable in much of the GaN currently produced due to the relative ease of preferential N2 loss and the common use of HT containing growth (and cool-down) ambients. Finally the ohmic contact behavior of WSix on abrupt and graded composition InxAl1-xN layers has been studied as a function of growth temperature, InN mole fraction x=0.5-1) and post WSix deposition annealing treatment. Rc values in the range 10-3/-10sup-5/ ω cm2 are obtained for auto-doped n+ alloys, with the n-type background being little affected by growth conditions (n∼1020 cm-3). InN is the least temperature-stable alloy (les/700°C), and WSix contact morphology is found to depend strongly on the epi growth conditions.
AB - We have sputter-deposited 500-1200 Å thick WSi0.45 metallization onto n+ GaN (n≥1019 cm-3) doped either during MOCVD growth or by direct Si+ ion implantation (5×1015 cm-2, 100 keV) activated by RTA at 1100°C for 30 secs. In the epi samples Rc values of ∼10-14 ω cm2 were obtained, and were stable to ∼1000°C. The annealing treatments up to 600°C had little effect on the WSix/GaN interface, but the beta/-W2N phase formed between 700-800°C, concomitant with a strong reduction (approximately a factor of 2) in near-surface crystalline defects in the GaN. Spiking of the metallization down the threading and misfit dislocations was observed at 800°C, extending >5000 Å in some cases. This can create junction shorting in bipolar or thyristor devices, Rc values of <10-6 ωcm2 were obtained on the implanted samples for 950°C annealing, with values of after 1050°C anneals. The lower Rc values compared to epi samples appear to be a result of the higher peak doping achieved, ∼5×1020 cm-3. We observed wide spreads in Rc values over a wafer surface, with the values on 950°C annealed material ranging from 10-7 to 10-4 ω cm2. There appear to be highly nonuniform doping regions in the GaN, perhaps associated with the high defect density (1010 cm-2) in heteroepitaxial material, and this may contribute to the variations observed. We also believe that near-surface stoichiometry is variable in much of the GaN currently produced due to the relative ease of preferential N2 loss and the common use of HT containing growth (and cool-down) ambients. Finally the ohmic contact behavior of WSix on abrupt and graded composition InxAl1-xN layers has been studied as a function of growth temperature, InN mole fraction x=0.5-1) and post WSix deposition annealing treatment. Rc values in the range 10-3/-10sup-5/ ω cm2 are obtained for auto-doped n+ alloys, with the n-type background being little affected by growth conditions (n∼1020 cm-3). InN is the least temperature-stable alloy (les/700°C), and WSix contact morphology is found to depend strongly on the epi growth conditions.
UR - http://www.scopus.com/inward/record.url?scp=0347515545&partnerID=8YFLogxK
U2 - 10.1109/HITEC.1998.676807
DO - 10.1109/HITEC.1998.676807
M3 - 会议稿件
AN - SCOPUS:0347515545
SN - 0780345401
SN - 9780780345409
T3 - 1998 4th International High Temperature Electronics Conference, HITEC 1998
SP - 296
EP - 300
BT - 1998 4th International High Temperature Electronics Conference, HITEC 1998
PB - Institute of Electrical and Electronics Engineers Inc.
T2 - 1998 4th International High Temperature Electronics Conference, HITEC 1998
Y2 - 14 June 1998 through 18 June 1998
ER -