ABSTRACT
The introduction of extra Si from SiNx cap during 950°C activation annealing of implanted Si in GaAs has been observed in two cases: one was the recoil of Si from SiNx mask due to through-nitride ion implantalion(T-N-II) of 28Si or 40Ar in GaAs and subsequent annealing; the other was the gettering of Si from SiNx cap after post-implantation annealing when SiF or SiF2 was implanted in GaAs as a Si source. For the T-N-II, the implantation condition was 4E13cm-2at 120KeV for Si or Ar with the initial nitride thicknesses in the range of 700 to 1500Å. The total Si dose of T-N-II after activation increased for nitride thicknesses less than 1100Å compared to the direct implantation without initial nitride, according to the secondary ion mass spectrometer (SIMS) depth profiles. However, the sheet resistance increased for all the Si T-N-H samples. Ar ions were implanted through-nitride of 700 to 1500Å thicknesses to find significant amount of Si in GaAs up to approximately 1000Å after annealing. The sheet resistances were not measurable for Ar T-N-II samples. Therefore, we suggest that the recoiled Si atoms were distributed in such a random fashion that the selective ordering redistribution of Si to the Ga sublattice sites was not enhanced for the activation condition of the present study. A dose of 4E 12cm-2 at the energy range of 30-130KeV has been implanted using SiF or SiF2 to find out that Si concentration increased significantly on the surface side of the projected ranges after activation annealing with SiNx cap according to SIMS. This is an evidence of the introduction of Si from the nitride during activation annealing. The TRIM-90 calculation was done to elucidate the mechanism of damage enhanced introduction of extra Si in GaAs during activation annealing.
