Metal-insulator-IV-VI compound semiconductor tunnel junctions were formed for both single and polycrystalline semiconductor material. I-V and conductance characteristics were taken as a function of temperature, and magnetic field. The experimental results were interpreted in terms of a conventional tunneling theory, and yielded information on Fermi energies, band gaps, temperature dependence of band gaps, work functions and electron affinities. Also obtained was information on deep levels which have large anisotropic g values and exist within the band gap of some of the semiconductors