Defect introduction in Ge during inductively coupled plasma etching and Schottky barrier diode fabrication processes

We have etched Sb-doped n-type (111) oriented Ge by inductively coupled plasma (ICP), using argon, and subsequently studied the defects that this process introduced as well as the effect of this etching on Schottky barrier diode quality. Deep level transient spectroscopy (DLTS) revealed that ICP etching introduced only one prominent defect, EP0.31, in Ge with a level at 0.31 eV below the conduction band. The properties of this defect are 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. DLTS depth profiling revealed the EP0.31 concentration was a maximum (3.6 × 1013 cm− 3) close to the Ge surface and then it decreased more or less exponentially into the Ge. Annealing at 250 °C reduced the EP0.31 concentration to below the DLTS detection limit. Finally, current–voltage (I–V) measurements as a function of temperature revealed that the quality of Schottky contacts fabricated on the ICP-etched surfaces was excellent at − 100 K the reverse leakage current at − 1 V was below 10 13 A (the detection limit of our I–V instrumentation).