A P-type mid-infrared transparent semiconductor LaSe2 film with small hole effective mass and high carrier concentration

Abstract

P-type transparent conductive materials (TCMs) are urgently needed in the development of photoelectric devices. In particular, the P-type TCMs that can be applied in the mid-infrared range are even rarer due to the conflict between the transparent range and the conductivity of materials. In this work, a P-type mid-infrared transparent conductive LaSe2 film is obtained by a two-step method combining the RF sputtering and a selenized annealing process. The crystal structure of the film has been confirmed by x-ray diffraction and Raman spectrum analysis. According to the Hall effect measurement results, the LaSe2 film has a higher conductivity (about 3.6 S/cm) than that of traditional P-type mid-infrared TCMs, which is attributed to its ten times higher carrier concentration (about 1019 cm−3) and a much smaller hole effective mass (about 0.34 me) compared to the conventional P-type mid-infrared TCMs. The transmittance (about 75%) is at the same level as that of the traditional P-type mid-infrared TCMs. In a sense, the LaSe2 is a promising candidate material for the development of mid-infrared photoelectric devices.