TY - JOUR
T1 - Thermal stability of WSix and W ohmic contacts on GaN
AU - Cao, X. A.
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.
AU - Baca, A. G.
N1 - Funding Information:
The work at UF is partially supported by a DARPA/EPRI grant (E.R. Brown/J. Melcher). Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed–Martin company for the US Department of Energy under contract No. DEAC04-94AL85000.
PY - 1999/5/6
Y1 - 1999/5/6
N2 - We have sputter-deposited 500-1200 angstrom thick WSi0.45 and W metallization onto both 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 1400°C for 10 s and p+ (NA = 1018 cm-3) GaN. In the n-type epi samples Rc values of 10-4 Ω cm-2 were obtained and were stable to approx. 1000°C. The annealing treatments up to 600°C had little effect on the WSix/GaN interface, but the β-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 angstrom in some cases. This can create junction shorting in bipolar or thyristor devices. Rc values of approx. 10MIN6 Ω cm-2 were obtained on the implanted samples for 950°C annealing, with values of approx. 10-5 Ω cm-2 after 1050°C anneals. On p-GaN, the contacts are essentially leaky Schottky diodes at 25°C, but became ohmic at ≥ 250°C, with Rc in the 10-2 Ω cm-2 range. The W-based metallization is much more thermally stable than the more common Ni/Au.
AB - We have sputter-deposited 500-1200 angstrom thick WSi0.45 and W metallization onto both 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 1400°C for 10 s and p+ (NA = 1018 cm-3) GaN. In the n-type epi samples Rc values of 10-4 Ω cm-2 were obtained and were stable to approx. 1000°C. The annealing treatments up to 600°C had little effect on the WSix/GaN interface, but the β-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 angstrom in some cases. This can create junction shorting in bipolar or thyristor devices. Rc values of approx. 10MIN6 Ω cm-2 were obtained on the implanted samples for 950°C annealing, with values of approx. 10-5 Ω cm-2 after 1050°C anneals. On p-GaN, the contacts are essentially leaky Schottky diodes at 25°C, but became ohmic at ≥ 250°C, with Rc in the 10-2 Ω cm-2 range. The W-based metallization is much more thermally stable than the more common Ni/Au.
UR - http://www.scopus.com/inward/record.url?scp=0033528901&partnerID=8YFLogxK
U2 - 10.1016/S0921-5107(98)00351-1
DO - 10.1016/S0921-5107(98)00351-1
M3 - 会议文章
AN - SCOPUS:0033528901
SN - 0921-5107
VL - 59
SP - 362
EP - 365
JO - Materials Science and Engineering B: Solid-State Materials for Advanced Technology
JF - Materials Science and Engineering B: Solid-State Materials for Advanced Technology
IS - 1-3
T2 - Proceedings of the 1998 Symposium L: on Nitrides and Related Wide Band Gap Materials (E-MRS Meeting)
Y2 - 16 June 1998 through 19 June 1998
ER -