Study of impurity states in p-type Hg_1-xCd_xTe using far-infrared spectroscopy

This letter reports the far-infrared (FIR) transmission spectra of undoped and Sb-doped p-type Hg_1-xCd_xTe films grown by a liquid-phase epitaxy (LPE) or molecular-beam epitaxy (MBE) technique. The activation energies of cation vacancy acceptor are found to be ∼10-12 meV and are almost independent on Cd composition. The absorption strength per Hg vacancy, useful for evaluating the cation vacancy density from the absorption spectra, is derived as 3.4×10^-12cm. Further, Zeeman splitting resulting from two different acceptors is observed from magnetotransmission measurement for the Sb-doped LPE sample, and light hole effective mass is estimated. FIR transmission seems to be a powerful tool for nondestructive characterization of impurity states in Hg_1-xCd_xTe.