Abstract
A commercially available 4H-SiC power device and a GaN on SiC HEMT were examined with Ga-FIB sectioning and various junction analysis techniques. The impact of Ga-FIB on the electronic properties of such power devices is observed to be less significant than anticipated. A field of view was FIB-milled into the structure, exposing a row of devices. In this window, p/n junctions were evaluated by Passive Voltage Contrast (PVC), Electron Beam Induced Current (EBIC), and Kelvin Force Probe Microscopy (KFPM). Results showed excellent fidelity to expectations and each technique brought out new insights. In further work, the gate voltage was varied and the changing of depletion zones upon device turn-on was observed. This work: 1) Demonstrates complete sufficiency of Ga-FIB cross sections for regular cross-sectional work. 2) Demonstrates a novel method for investigating junction properties from Ga-FIB sections of power devices which largely leaves the rest of the device intact. 3) Provides some assurance that the Ga-FIB does not severely impact the evaluation of junction properties in some power semiconductors. 4) Points to alternative mechanism for device turn-on.
