ELECTRONIC TRANSPORT IN SI AND GE POLYMERS

Time-resolved transport studies which have now been carried out on a w ide variety of alkyl- and aryl-substituted Si and Ge backbone polymers demonstrate the ability of these unipolar systems to transmit holes t hrough the specimen bulk with negligible loss of these positive carrie rs to deep traps, making these materials attractive candidates for ele ctronic device applications. Transport has been studied by measuring d rift mobilities as a function of field, temperature and composition, u sing the small-signal time-of-flight technique. Transport occurs among chain backbone derived states, yet exhibits behavior essentially iden tical to systems in which transiting carriers are known to undergo the rmally activated tunneling transitions among discrete molecular sites. On this basis it is suggested that disorder causes the chain backbone to be sub-organized into domain-like units of varying conjugation len gth. The sensitivity of transport to large-scale thermodynamic process es, side-group substituent and effect of specific dopants is demonstra ted.