Thin films of bismuthhyphen;germanium have been fabricated by the method of codeposit vapor quenching onto liquid nitrogen or waterhyphen;cooled substrates. Structural, electrical, optical, and photoelectrical characterizations of these films have been accomplished. In this paper, Paper I of a twohyphen;paper series, the structural and electrical characterization results are reported. Xhyphen;ray diffraction measurements indicate that a stable amorphous phase exists for the BixGe1minus;xthinhyphen;film system for 0 le;xle; 0.12. Lowhyphen;field dc resistivity as a function of temperature from room temperature to liquidhyphen;nitrogen temperature and relative thermopower measurements show that in the amorphous range the BixGe1minus;xthin films arenhyphen;type semiconductors with a continuously decreasing thermal activation energy asxincreases. The resistivity of amorphous bismuthhyphen;germanium films decreases with an increase in bismuth concentration. Currenthyphen;voltage data taken on several films at 300 and 162deg;K indicate Ohmic behavior with no evidence of Poolehyphen;Frenkel, Schottkyhyphen;barrier, or switching effects. A structural model for the amorphous bismuthhyphen;germanium system is proposed with covalent hybrid bonding of monoatomic bismuth to a Polkhyphen;Turnbull amorphous germanium random network. An energyhyphen;band densityhyphen;ofhyphen;states model is proposed based on the Weairehyphen;Thorpe interpretation of the Polkhyphen;Turnbull network and considerations from the theory of heavily doped semiconductors. The proposed structural and energyhyphen;band models are utilized to explain the observed electrical and optical properties.
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