W. Österle^a, P. Ressel^b

Published in:

Mater. Sci. Eng., B, vol. 40, no. 1, pp. 42-49 (1996).

Abstract:

Cross-sectional transmission electron microscopy, in combination with energy dispersive X-ray spectroscopy and focused beam microdiffraction, was applied to study the solid-state reactions taking place during contact formation of the system Ge(115 nm)/Pd(50 nm)-In_0.53Ga_0.47As. In order to get information about the sequence of the different processes, rapid thermal, annealing experiments in the range 225-400 °C were performed. The following features were observed: at 225 °C Pd reacted with the substrate forming the quaternary phase Pd_xIn_0.53Ga_0.47As (x ≈ 4), and with the Ge-layer forming mainly PdGe and Pd₂Ge. Between Pd_xIn_0.53Ga_0.47As and In_0.53Ga_0.47As, a 5 nm thick amorphous Pd-In-Ga-As layer remained, indicating that the first reaction step was solid-state amorphization. After annealing at 350 °C, Pd_xIn_0.53Ga_0.47As disappeared and regrowth of In_0.53Ga_0.47As occured. Finally, at 400 °C, residual Ge from the amorphous top layer diffused to the interface and grew epitaxially on the regrown In_0.53Ga_0.47As, thus separating the III-V compound semiconductor from the Pd-Ge reaction products. The interface remained flat, while only about 10 nm of the active In_0.53Ga_0.47As layer had been modified during the annealing processes.

Keywords:

XTEM investigations; Solid-state reactions; Rapid thermal annealing.

© Copyright 1996 Elsevier B.V. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the Elsevier B.V..

Full version in pdf-format.