ELECTRICAL AND STRUCTURAL CHARACTERIZATION OF NI GE/N-GAAS INTERFACE/

The structural and electrical behaviour of Ni/Ge layers deposited onto n-type GaAs by electron beam evaporation were studied. The samples ha ve been annealed for 20 min at different temperatures in flowing formi ng gas-H-2:N-2 (5%:95%)-in a tube furnace. When the annealing temperat ure was increased the Schottky barrier heights calculated from I-V and C-V characteristics decreased, and the I-V characteristics of the sam ples heat treated at 600 degrees C became linear. The contact resistan ce of the samples with linear characteristic was measured with Cox met hod. The calculated specific resistivity was 4.4 x 10(-4) ohmcm(2) in the case of sample heat treated at 550 degrees C and 5.1 x 10(-5) ohmc m(2) after annealing at 600 degrees C. In the sample annealed at 550 d egrees C protrusions appeared with the size of 20-30 nm at the interfa ce of semiconductor-metal. Detectable amount of Ge was found in additi on to Ni, As, and G in the protrusions. Moreover, those features conta in significantly less Ga than As. The protrusions containing Ge play a role in the formation of the low barrier contact. (C) 1998 Elsevier S cience Ltd. All rights reserved.