Sb-doped n-type (111) oriented Ge was etched by inductively coupled plasma, using argon, and the defects that this process introduced were studied, as well as the effect of the etching upon Schottky barrier diode quality. Deep-level transient spectroscopy revealed that inductively coupled plasma etching introduced only one prominent defect, EP0.31, in Ge with a level at 0.31eV below the conduction band. The properties of this defect were different to those of defects introduced by other particle-related processing steps, e.g. sputter deposition and electron beam deposition, that each introduces a different set of defects. Deep-level transient spectroscopy depth profiling revealed that the EP0.31 concentration was a maximum (3.6 x 1013/cm3) close to the Ge surface and then it decreased more or less exponentially into the Ge. Annealing at 250C reduced the EP0.31 concentration to below the deep-level transient spectroscopy detection limit. Finally, current–voltage (I–V) measurements as a function of temperature revealed that the quality of Schottky contacts fabricated on the inductively coupled plasma-etched surfaces was excellent at −100K the reverse leakage current at −1V was below 1013A (the detection limit of the present I–V instrumentation).

Defect Introduction in Ge during Inductively Coupled Plasma Etching and Schottky Barrier Diode Fabrication Processes. F.D.Auret, S.M.M.Coelho, G.Myburg, P.J.J.van Rensburg, W.E.Meyer: Thin Solid Films, 2010, 518[9], 2485-8