Electron-beam-induced current imaging for the characterisation of structural defects in Si1−xGex films grown by LE-PECVD

We present a comparison of two different techniques for the evaluation of Threading Dislocation Density (TDD) in Si1−xGex graded buffers: chemical etching and Electron-Beam-Induced-Current (EBIC) imaging. The samples analyzed consist of a series of linearly graded Si1−xGex buffers terminated by a constant composition layer with Ge concentration varying between 0.2 and 0.9. The films were deposited on Si(1 0 0) wafers by means of Low Energy Plasma Enhanced CVD (LE-PECVD). Our results indicates that EBIC proves to be a versatile method, which provides reliable information on the defect concentration up to a   Ge concentration of x=0.4x=0.4. For higher values of x  (x=0.7)(x=0.7) the information is approximated but yet reliable for the purpose of optimising the growth process. In order to perform EBIC   measurements on samples with higher Ge concentrations (x=0.9)(x=0.9), the Schottky diode fabrication has to be improved.