An investigation of pnp polysilicon emitter transistors

The d.c. characteristics are computed for pnp polysilicon emitter transistors (PETs) in which a thin insulating layer is incorporated in the emitter structure. Both devices with, and without, a post-polysilicon deposition annealing treatment are modeled. The effects of the annealing are taken to be a reduction in the insulator thickness and the creation of a p-type monosilicon emitter region. The simulations reveal that moderate current gains, around 300, are possible with these devices

Distribution of base dopant for transit time minimization in a bipolar transistor

A means to determine the doping profile minimizing base transit time in a bipolar transistor is presented, assuming that the width of (he neutral base is held constant. It is found that the optimum profile is not close to the exponential decrease from emitter to collector predicted by earlier studies

An Analytic Model for the MIS Tunnel Junction

A comprehensive analytic model describing current flow in the MIS tunnel junction under steady-state conditions is developed. The tunnel junction is viewed as imposing boundary conditions on the usual set of differential equations governing the electrostatic potential and carrier distributions within the semiconductor. These equations are then solved using the approximation techniques applied in conventional p-n junction theory. Full Fermi-Dirac statistics are used where necessary in the model, and surface states are treated using a Shocklley-Read-Hall approach. In computing the band-to-metal tunnel currents, it is assumed that each valley in the conduction band and peak in the valence band can be assigned a single tunneling probability factor describing all transitions between that valley or peak and the metal. On making the above approximations, it is found that the state of the junction is described by two coupled nonlinear algebraic equations, which can be solved by routine iterative techniques. The model is applied to generate current-voltage characteristics for a minority-carrier Al-SiOxpSi diode, operated both in the dark and as a solar cell, and for a negative barrier Al-SiOx-nSi contact exhibiting photocurrent multiplication. The results obtained are in good agreement with those predicted by more precise numerical methods. Copyrigh