Accession Number : AD0451775


Title :   FIELD-EFFECT AND SPACE-CHARGE-LIMITED THINFILM TRIODES.


Descriptive Note : Rept. no. 4 (Final), 1 Jul 63-30 JKUN $,


Corporate Author : RAYTHEON CO WALTHAM MA


Personal Author(s) : Laznovsky, W H ; Shallcross, F V ; Weimer, P K ; Wennik, L P


Report Date : 31 Jul 1964


Pagination or Media Count : 86


Abstract : During this program, materials and techniques were studied to improve the reproducibility and stability of CdS TFTs, and to obtain an understanding of the failure mechanisms. Early in the program the average life of TFTs (as measured, for example, by the half-life of the value of g sub m) was on the order of days. At the conclusion of the program life has been extended to over a year. The fall-off in g sub m for CdS TFTs is now comparable to the degradation rate of germanium transistors which have not been aged. Success with vacuum-encapsulated hermetically sealed units shows the significance of adverse ambients, particularly oxygen. Vitreous selenium encapsulation is equally effective, judging from early results of testing. Crowding of characteristics is associated with oxidation of contact interfaces. A second type of instability-a short time variation-was studied; this is associated with trapped charge and charge migration under field. Control of this calls for control of charge included in the evaporated film. Results of the program show that a stable TFT may be achieved by proper fabrication and sealing. Indicatios are that a postfabrication aging process would yield extremely stable devices. (Author)


Descriptors :   SEMICONDUCTING FILMS , VAPOR PLATING , MANUFACTURING , STABILITY , ELECTRICAL CONDUCTIVITY , TRANSISTORS , LIFE EXPECTANCY(SERVICE LIFE) , ENCAPSULATION , TEMPERATURE , ELECTRODES , COATINGS , CADMIUM COMPOUNDS , SULFIDES , TELLURIUM , SURFACE PROPERTIES , SPACE CHARGE


Distribution Statement : APPROVED FOR PUBLIC RELEASE