Annealing Study of Al/GaSb Contact with the Use of Doppler Broadening Technique
H.Y. Wanga,bH.M. Wengb, C.C. Linga, B.J. Yeb, X.Y. Zhoub and R.D. Hanb
aDepartment of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
bDepartment of Modern Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
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Received: 20 09 2004;
Using a monoenergetic positron beam, annealing study of the Al/n-GaSb system was performed by monitoring the Doppler broadening of the annihilation radiation as a function of the positron implanting energy. The S-parameter against positron energy data was successfully fitted by a three-layer model (Al/interface/GaSb). The annealing out of the open volume defects in the polycrystalline Al layer was revealed by the decrease in the S-parameter and the increase in the effective diffusion length of the Al layer. For the as-deposited samples, a∼5 nm interfacial region with S-parameter larger than those of the Al overlayer and the bulk was identified. After the 400^ºC annealing, this interfacial region extends to over 40 nm and its S-parameter dramatically drops. This is possibly due to the new phase formation at the interface. Annealing behaviors of SB and L+,B of the GaSb bulk showed the annealing out of positron traps (possibly the VGa-related defect) at 250ºC. However, a further annealing at 400ºC induces the formation of positron traps, which are possibly of another kind of VGa-related defect and the positron shallow trap GaSb antisite.
DOI: 10.12693/APhysPolA.107.874
PACS numbers:78.70.Bj, 68.35.Ct, 73.40.Sx