METHODS FOR MAGNETOTRANSPORT CHARACTERIZATION OF IR DETECTOR MATERIALS

Advanced techniques for the magnetotransport characterization of semiconductor IR detector materials are reviewed. Both conventional mixed-conduction and 'mobility spectrum' analyses of the resistivity tensor as a function of magnetic field and temperature are discussed, as well as a hybrid approach which exploits the advantages of both methods. Assuming that the data are sufficiently sensitive, one obtains concentrations and mobilities for each electron and hole species present in a given sample. This is particularly valuable for narrow-gap infrared detector materials such as Hg1-xCdxTe, since the coexistence of multiple species tends to be the rule rather than the exception, and 'anomalous' Hall data are easily misinterpreted if inferences are drawn from measurements at only a single magnetic field. In addition to bulk electron and hole densities and mobilities, one can determine inversion and accumulation layer properties from the anomalous Hall effect, acceptor binding energies and compensation ratios from the low-temperature freeze-out of free holes, and energy gaps from the temperature dependence of the intrinsic carrier concentration. Shubnikov-de Haas and quantum Hall measurements provide additional information about the spatial distribution of the carriers. Electron and hole mobilities in Hg1-xCdxTe detector materials will be briefly reviewed, and theoretical and experimental results compared.