Bulk Voltage Research Articles

Experimental study of bulk limitation of the current in hydrogenated amorphous silicon diodes

We have utilized a series model to separate the bulk limitation of current from junction effects in amorphous silicon p-i-n devices. The equivalent circuit consists of a forward bias junction in series with the nonlinear bulk behavior. Analysis of our experimental data shows that the bulk current density can be described by power law dependences upon the bulk voltage and intrinsic layer thickness. This identification of the bulk behavior allows us to make quantitative comparisons between the p-i-n and n-i-n devices under steady state conditions.

The forward biased, Abrupt p- n junction

The abrupt, forward biased pn-junction is solved very accurately for its terminal characteristics and injection efficiency for all values of forward bias. This is accomplished by using a three-region approach and formulating the transport problem in terms of the local pn-product. Analytic solutions are derived for low, medium and high injection conditions. The low injection regime is characterized by negligible majority carrier density increases. However, in this injection region bulk width modulations due to decreasing transition layer widths modify the standard diffusion model results. The medium injection condition prevails if majority carrier density changes due to injection are significant on the lightly doped side of the junction. This as well as an inreasing bulk voltage drop are taken into account to establish new relationships for injection efficiency, which is decreasing with injection, and the terminal characteristics. The high injection regime involves significant majority carrier modulation in both bulk regions. The injection efficiency becomes a constant which is determined by mobility differences since diffusion currents are negligible. The transition region vanishes in width and its total voltage drop goes to zero. The current through the device is governed by a power law because it is a conductivity modulated resistor.

On some general laws of DC-DC regulators

Some general properties and limits of regulator technology are examined independent of circuit topology or device physics. As foundation, the work of Moore and Wilson on DC-DC conversion circuits is used. Their work showed the need for some intermediate DC-AC inversion in the converter. These findings are extended and applied to a dc-dc regulator, defined as a special network deriving all its power from a bulk source and supplying regulated DC to a load. It is subject to changes in environment bulk voltage fluctuations, load changes, etc. A dc-dc regulation can be performed with maximum efficiency and without circuit redundancy by two classes of regulators. They are the modulated source and modulated transmission regulators. The operating frequency of the modulated source regulator is established via sampled-data theory. A similar constraint on the modulated transmission regulator is governed indirectly, by the Manley-Rowe type power gain relationship.

Double injection in PπN silicon devices

Investigation of the d.c. electrical behavior of semiconductor P + πN + double injection devices is presented. The samples studied were fabricated from indium-doped silicon partially compensated by shallow donor impurities and were biased into the double injection (post-breakdown) regime at a temperature of 77°K. A numerical computer solution of the steady-state characteristic has been completed in order to explain the experimental d.c. data. The analysis reveals that electron-hole scattering is largely responsible for the increase in bulk voltage with current. In order to obtain agreement between the numerical solution and the experimental data, the filamentary nature of the double injection current is demonstrated.