Dopant Profiling in the TEM: Progress Towards Quantitative Electron Holography

Off-axis electron holography promises to fulfil the demands of the semiconductor industry for a technique that can provide information about dopants with nm-scale resolution. Typically, when examining focused-ion-beam-prepared specimens containing p-n junctions, the theoretical built-in potential is not recovered, even after accounting for the presence of damaged surface layers. Here we show that the potentials measured in simple GaAs n-p junctions are strongly dependent on the intensity of the incident electron beam, and that by attaching electrical connections to the specimen, the correct built-in potential call be recovered.