Contactless THz-based bulk semiconductor mobility measurements using two-photon excitation.

We perform contactless bulk mobility measurements for ZnSe, ZnTe, GaP, CdS, and GaSe in an optical pump THz probe experiment. As opposed to above-gap excitation or contact methods, two-photon absorption excites the entire sample thickness producing measurable signals with 1013 carriers/cm3 and higher density. For ZnTe and GaSe samples, the measured mobility using two-photon excitation is higher than that measured with one-photon excitation.