Microstructural Characterization
Failure of semiconductor devices is often apparent in microstructural changes; it causes defect formation, gate sinking and other undesirable effects. We use transmission electron microscopy and focused ion beam based techniques, to gain insight into failure modes of devices to improve our understanding of the microstructure of novel material systems such as GaN-on-diamond – amongst others.
Figure 1 . Computed x-ray tomography
Figure 2. Two bright field TEM images of the GaN on Polycristalline Diamond sample in (a) g=(0002) and (b) g=(10-10) two-beam conditions. Two white arrows indicate the positions where threading dislocations (in the g=(0002) conditions) terminate at stacking faults. The inset of (a), taken from region ‘A’, shows the annihilation of two dislocations and the interaction of threading dislocations with stacking faults. A selected area electron diffraction pattern taken from a region including the GaN/diamond interface is shown in (c). This shows a [11-20] zone axis diffraction pattern of the GaN and two additional spots from the diamond substrate (highlighted in blue).