Investigation of Multicarrier Transport in LPE-Grown Hg1-xCdxTe Layers

A detailed study is presented of multicarrier transport properties in liquid-phase epitaxy (LPE)-grown n-type HgCdTe films using advanced mobility spectrum analysis techniques over the temperature range from 95 K to 300 K. Three separate electron species were identified that contribute to the total conduction, and the temperature-dependent characteristics of carrier concentration and mobility were extracted for each individual carrier species. Detailed analysis allows the three observed contributions to be assigned to carriers located in the bulk long-wave infrared (LWIR) absorbing layer, the wider-gap substrate/HgCdTe transition layer, and a surface accumulation layer. The activation energy of the dominant high-mobility LWIR bulk carrier concentration in the high temperature range gives a very good fit to the Hansen and Schmit expression for intrinsic carrier concentration in HgCdTe with a bandgap of 172 meV. The mobility of these bulk electrons follows the classic mu similar to T-3/2 dependence for the phonon scattering regime. The much lower sheet densities found for the other two, lower-mobility electron species show activation energies of the order of similar to 20 meV, and mobilities that are only weakly dependent on temperature and consistent with expected values for the wider-bandgap transition layer and a surface accumulation layer.