Abstract
Crystalline Ge and Si1-xGex alloys (x = 0.83, 0.77) of (100) orientation were implanted with 140 keV Ge- ions at fluences between 5 x10(15) to 3 x 10(17) ions/cm (2), and at temperatures between 23 degrees C and 200 degrees C. The energy deposition of the ions leads to the formation of porous structures consisting of columnar pores separated by narrow sidewalls. Their sizes were characterized with transmission electron microscopy, scanning electron microscopy, and small angle x-ray scattering. We show that the pore radius does not depend significantly on the ion fluence above 5 x 10(15) ions/cm (2), i.e., when the pores have already developed, yet the pore depth increases from 31 to 516 nm with increasing fluence. The sidewall thickness increases slightly with increasing Si content, while both the pore radius and the sidewall thickness increase at elevated implantation temperatures. Published by AIP Publishing.