A photoionization detector (PID) is disclosed that includes an ionization chamber configured to allow a flow of a gas sample therethrough, the ionization chamber defining an ionization region and a detection region, a photoionization source configured to generate ionizing radiation for irradiating the flow of the gas sample in the ionization region, an electric-field ionization source configured to apply an ionizing electric field inside the ionization chamber to intersect the flow of the gas sample in the ionization region, the ionizing radiation and the ionizing electric field being configured to ionize the gas sample, and an ion detector configured to detect, in the detection region, an ionization current resulting from the ionized gas sample. The PID may also include an optical window, for example, made of a window material including sapphire, configured to allow at least part of the ionizing radiation to pass therethrough prior to entering the ionization region.