ABSTRACT
Present a transmission electron microscopy (TEM) analysis of a series of Si/SiGe resonant tunnelling diode structures which contain Si1-xGex quantum wells rown on a range of Sil-yGey virtual substrates. It is found that the dislocation density in the graded region of the virtual substrate increases with the y parameter, as expected. In resonant tunnelling diode (RTD) structures fabricated using III-V materials have reached a mature stage and exhibit good electrical characteristics. However, with the vast majority of the microelectronics industry being based on Si technology, there is increasing interest in developing strain-balanced Si/SiGe virtual substrate based RTD devices. Detailed surface topography observations were made by atomic force microscopy, using a Digital Instruments Nanoscope III equipped with a microfabricated silicon stylus, operating in tapping mode. TEM is used to investigate the microstructure of a selection of RTD based device structures.
