Selenium vacancies induced surface oxygen adsorption and sensitization mechanism of PbSe film: Experimental and computational.

[Display omitted] • Oxygen sensitization mechanism of PbSe films is verified by the experiment and theoretical calculation. • The effect of Se vacancies on the conductive type of PbSe and their role in the process of oxygen sensitization are described. • New energy levels formed by O atoms decreases carrier concentration and enhances carrier mobility is demonstrated. • Oxygen sensitization inhibites the dark current and improves the mobility of photon-generated carriers, leads to the enhancement of photodetection performance. Lead selenide (PbSe) is widely considered to be an ideal material for room temperature mid-wave infrared (MWIR) detection. The MWIR response of PbSe leaps obviously after sensitization in a particular oxidizing process. However, the mechanism of such characteristics has not been specifically understood. Here, the oxygen (O) sensitization reaction process is affirmed by experiment and computation. In the process of film preparation, Se atoms fractionate from the (2 0 0) plane of PbSe lattice and leave Se vacancies (V Se). Then, O 2 molecules adsorbed at V Se and subsequently disintegrate into O atoms occupying V Se. The O indrawing forms new energy levels and reduces the band gap (E g), realizes the conductivity transformation from n- to p-type, decreases carrier concentration, and enhances carrier mobility. The variation of conductivity inhibits the dark current of PbSe detectors and increases the mobility of photon-generated carriers at the same time, resulting in the improvement of the IR detection performance. [ABSTRACT FROM AUTHOR]