  We demonstrate the application of two-photon absorption transient current
technique to wide bandgap semiconductors. We utilize it to probe charge
transport properties of single-crystal Chemical Vapor Deposition (scCVD)
diamond. The charge carriers, inside the scCVD diamond sample, are excited by a
femtosecond laser through simultaneous absorption of two photons. Due to the
nature of two-photon absorption, the generation of charge carriers is confined
in space (3-D) around the focal point of the laser. Such localized charge
injection allows to probe the charge transport properties of the semiconductor
bulk with a fine-grained 3-D resolution. Exploiting spatial confinement of the
generated charge, the electrical field of the diamond bulk was mapped at
different depths and compared to an X-ray diffraction topograph of the sample.
Measurements utilizing this method provide a unique way of exploring spatial
variations of charge transport properties in transparent wide-bandgap
semiconductors.
