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Semi-insulating InP single crystals co-doped with Zn and Ti and co-doped with Ti and Mn were grown by Czochralski technique. Wafers of these crystals were annealed for a long time at a high temperature and cooled slowly. The samples were characterized by temperature dependent resistivity and Hall coefficient measurements. The binding energies of Ti in semi-insulating InP co-doped with Ti and Zn and co-doped with Ti and Mn were found to differ which shows that Ti may occupy different sites in InP. The curves of Hall coefficient vs. reciprocal temperature deviate from straight lines at low temperatures due to electron and hole mixed conductance. The value of resistivity of the annealed semi-insulating InP co-doped with Ti and Mn reaches high resistivity at a reduced temperature easily achievable by thermo-electric devices which could make this material useable in X-ray detection. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Copper doped InP crystals were synthesized by Bridgman method and further grown by Czochralski technique. Samples of as grown crystals were of n-type conductivity with the estimated concentration of copper smaller than 5 × 1015 cm–3. The electron mobility in these samples is largely reduced at low temperatures, which is attributed to a strong scattering of electrons on copper impurities similar to other atomic impurities with partly occupied 3d shells. The samples were converted to p-type semi-insulating state after annealing at 500 °C and quenched to room temperature. The energy of copper acceptor causing the semi-insulating state was determined by temperature dependent Hall measurements as 0.29 eV in agreement with the low temperature photoluminescence spectroscopy. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

High purity InP crystals were grown by liquid encapsulated Czochralski method from undoped InP melt. Wafers from the grown crystals were annealed in phosphorus ambient for 95 hours at 950 °C and cooled slowly. Conversion to semi-insulating state by annealing was studied by temperature dependent Hall measurements and low temperature optical absorption spectroscopy.

High purity InP crystals were grown by liquid encapsulated Czochralski method from undoped InP melt. Wafers from the grown crystals were annealed in phosphorus ambient for 95 hours at 950 °C and cooled slowly. Conversion to semi-insulating state by annealing was studied by temperature dependent Hall measurements and low temperature optical absorption spectroscopy.

As observed for many types of cancers, heritable variants of ultraviolet light-induced tumors often grow more aggressively than the parental tumors. The aggressive growth of some variants is due to the loss of a T cell-recognized tumor-specific antigen; however, other variants retain such antigens. We have analyzed an antigen retention variant and found that the variant tumor cells grow at the same rate as the parental tumor cells in vitro, but grew more rapidly than the parental cells in the T cell-deficient host. The growth of the variant cells was stimulated in vitro by factors released from tumor-induced leukocytes and by several defined growth factors. In addition, the variant cancer cells actually attracted more leukocytes in vitro than the parental cells. Furthermore, elimination of granulocytes in vivo in nude mice by a specific antigranulocyte antibody inhibited the growth of the variant cancer, indicating that this tumor requires granulocytes for rapid growth.