rack. II-43 One fortunate difference between SEB and SEGR is that non-destructive test procedures exist for SEB. In the simpler of these techniques, a load resistor attached to the drain of the MOSFET provides current limiting and prevents destructive SEB [217]. Current pulses at the source can be counted as SEB events and the SEB cross-section can be non-destructively obtained as a function of either the drain voltage or the particle LET. A newer technique, called Energetic Particle- Induced Charge Spectroscopy (EPICS), measures the collected charge from SEB events rather than sensing current pulses [218]. This technique was developed to give more information on the triggering mechanisms responsible for SEB, and has offered experimental confirmation of the mechanisms described above. An example of results using EPICS for power MOSFETs is shown in Figure 4.9 [218]. At low drain voltages (Fig. 4.9a), a single peak at a collected charge of about 10 pC was observed and corresponded to charge collection in the depletion layer. At moderate drain voltages (Fig. 4.9b), a second peak appears and indicates that the parasitic BJT has been turned on and the source is injecting current into the device. Note that the original peak also moves to the right (higher charge collection) somewhat. This movement was postulated to be due to avalanche multiplication of the primary ion-induced current [218]. At still higher drain voltages (Fig. 4.9c), the regenerative feedback mechanism is established and SEB occurs. This results in a new peak with 3-4 orders of magnitude more collected charge; this peak is the characteristic signature of SEB in EPICS measurements. A new variation on the EPICS technique was recently reported by Kuboyama, et al. [216]. In this study, the authors connected an EPICS system to both the base and collector electrodes of the bipolar transistors under test. Using the "2-dimensional" EPICS spectra, the authors were able to distinguish between SEB events due to ion strikes to different areas of the emitter. 2SK72