MEASUREMENT OF INTERFACIAL CHARGE-TRANSFER RATE CONSTANTS AT N-TYPE INP CH3OH JUNCTIONS/

Steady-state current density vs potential methods have been used to me asure interfacial electron-transfer rate constants at n-type indium ph osphide/liquid junctions. n-InP/CH3OH-1,1'-dimethylferrocene(+/0), n-I nP/CH3OH- ferrocene(+/0), nP/CH3OH-tetrahydrofuran-decamethylferrocene (+/0), and n-InP/CH3OH-1,1'-diphenyl-4,4'-dipyridinium(2+/+.) contacts displayed bimolecular kinetic behavior in which the observed current density was first order in the concentration of electrons at the semic onductor surface and in the concentration of accepters in the solution . Differential capacitance potential measurements were used to determi ne the energetics for the charge-transfer process as well as to determ ine the concentration of electrons at the semiconductor surface as a f unction of applied potential. These measurements indicated that the vo ltage dropped across the semiconductor space charge region varied line arly with changes in the Nernst potential of the solution, as expected for an ideally behaving semiconductor/liquid junction. The measured c harge-transfer rate constants, k(et) for these systems were approximat e to 10(-16) cm(4) s(-1), in excellent agreement with previous theoret ical predictions.