Properties of metal semiconductor contacts—I voltage-current characteristics of contacts on intrinsic semiconductors

Abstract

In the general case (two carriers, arbitrary lifetime, arbitrary dielectric relaxation time), the transport equations relating to barrier characteristics have to be solved by numerical methods. The single-carrier case is already (abundantly) familiar, but the two-carrier case can also be solved explicitly. However, the solution is at all simple only for contacts on high lifetime intrinsic material. Such a solution is here obtained by conventional analytic methods, based on the diffusion theory and reasonable approximations, and is compared with computed results obtained on the complete (unapproximated) system. Analysis and computation lead to new and hitherto unrecognized dependence of the current on the applied voltage across the barrier in accordance with exp[2 qV a / kT], instead of the more familiar exp[ qV a / kT]. The computational aspects as such receive detailed attention in Part II. The conclusions have important implications for the interpretation of non-ideality factors. The intrinsic case here treated reflects general modes of behavior; more specific results for extrinsic systems will be presented in Part III.