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Electrical conduction in amorphous GeTe films
JOURNALOFNON-CRYSTALLINE SOLIDS2 (1970)239© North-HollandPublishingCo.,Amsterdam
E L E C T R I C A L C O N D U C T I O N IN A M O R P H O U S GeTe FILMS S. K. BAHL and K. L. CHOPRA Kennecott Copper Corp., Lexington, Massachusetts, U.S.A.
In contrast to the degenerate (metallic) conduction in crystalline GeTe films, the amorphous GeTe films exhibit intrinsic dc conduction with an apparent band gap ,-~0.6-0.8 eV. The ac conductivity of the amorphous form increases as o~" (n < 1) to approach a constant value above o~=90 kc/s. Simultaneously, the activation energy for conduction decreases continuously to zero. The observed behavior is explained in terms of conduction (a) in the conduction band by intrinsic excitation and (b) by a hopping process in the trap-like localized levels above the Fermi level in the valence band. The results of detailed studies of the structural optical, and electrical properties of amorphous versus crystalline GeTe films are being published by the authors as follows: 1) J. Vacuum Sci. Technol., July-August, 1969. 2) J. Appl. Phys., September, 1969 (I - Structural properties). 3) J. Appl. Phys., October, 1969 (II - Optical properties). 4) J. Appl. Phys., February, 1970 ( I I I - Electrical properties).
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E L E C T R I C A L C O N D U C T I O N IN A M O R P H O U S GeTe FILMS S. K. BAHL and K. L. CHOPRA Kennecott Copper Corp., Lexington, Massachusetts, U.S.A.
In contrast to the degenerate (metallic) conduction in crystalline GeTe films, the amorphous GeTe films exhibit intrinsic dc conduction with an apparent band gap ,-~0.6-0.8 eV. The ac conductivity of the amorphous form increases as o~" (n < 1) to approach a constant value above o~=90 kc/s. Simultaneously, the activation energy for conduction decreases continuously to zero. The observed behavior is explained in terms of conduction (a) in the conduction band by intrinsic excitation and (b) by a hopping process in the trap-like localized levels above the Fermi level in the valence band. The results of detailed studies of the structural optical, and electrical properties of amorphous versus crystalline GeTe films are being published by the authors as follows: 1) J. Vacuum Sci. Technol., July-August, 1969. 2) J. Appl. Phys., September, 1969 (I - Structural properties). 3) J. Appl. Phys., October, 1969 (II - Optical properties). 4) J. Appl. Phys., February, 1970 ( I I I - Electrical properties).
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