Temperature and Composition Dependence of Photovoltaic Spectra of Pb$\text{}_{1-x}$Mn$\text{}_{x}$Se Diodes

Photovoltaic spectra of Pb$\text{}_{1-x}$Mn$\text{}_{x}$Se homojunctions have been measured in the infrared spectral region within the temperature range 15-300 K. The junctions have been formed by cadmium diffusion into the p-type Pb$\text{}_{1-x}$Mn$\text{}_{x}$Se crystals with manganese content 0 ≤ x ≤ 0.08. From the positions of the photovoltaic maxima the energy band gap of the diode material has been determined. A phenomenological expression describing the energy band gap of Pb$\text{}_{1-x}$Mn$\text{}_{x}$Se as a function of temperature and crystal composition has been proposed. In diodes containing high manganese content x = 0.06 and x = 0.08 a second photovoltaic maximum caused by indirect optical transitions between the main conduction band and the secondary valence band located along the $\Sigma$-axis of the Brillouin zone has been observed.