Miron J. Cristea, Ph.D.

For info on my Power Semiconductor Devices course, please follow this link.

For my blog powsemdev.blogspot.com, click here.

My breakthrough research:

"Calculation of the Depletion Region Width and Barrier Capacitance of Diffused Semiconductor Junctions with Application to Reach-Through Breakdown Voltage of Semiconductor Devices with Diffused Base" presented at the International Semiconductor Conference CAS 2007 (an IEEE event), Sinaia, Romania.

"A very nice piece of analytical work with an explicit solution on the depletion capacitance of a Gaussian impurity profile"

C.T. Sah - Professor at University of Florida, IEEE Life Fellow, author of the article: C.T. Sah, R.N. Noyce, W. Shockley, "Carrier Generation and Recombination in p-n Junction and p-n Junction Characteristics", 1957.

"Let me first congratulate you with your results that seem to be very interesting for the theory of pn junctions"

N. Rinaldi - Professor at University of Naples, Italy, member of the Device Physics Committee of the IEEE Bipolar/BICMOS Circuits and Technology Meeting (see BCTM Boston, 2007 Committee).

"My congratulations for your new results about Gaussian p-n junctions"

B. Pellegrini - Professor at University of Pisa, author of the article: "A simplified model of ideal and almost ideal silicon p-n junctions: The role of oxigen", J. Appl. Phys., 1992.

For more than 50 years, nobody could infer an analytical formula for the depletion region width (barrier capacitance) of diffused (Gaussian) semiconductor junctions using only the basic depletion approximation. Until now. Why? Because the integration of the Poisson equation

cannot be done for a dependence like

- Gaussian function of the doping profile of diffused junctions, unless using the erf function, which is not analytical (elementary function), but tabulated (non-elementary), or using simple exponential exp(x) approximations (or a sum of simple exponentials), or by numerical integration (computer approach).

How was it done in this work? By using a new fundamental physics formula, applied to semiconductor junctions:

where x₁ and x₂ are the spatial limits of the space charge region - SCR (in the broadest sense), V_SCR is the voltage drop across the SCR (i.e. V(x₂)-V(x₁)) and E(x) is the electric field.

In the case of a reverse biased semiconductor junction

because the electric field is zero at both ends of the SCR. V_bi is the built-in junction potential and V_R is the externally applied reverse voltage.

This formula can be integrated in the case of Gaussian doping distribution. The results are presented in the conference paper.

^E-mail: miron.cristea@gmail.com

NEW C-V method devised and proved, based on the discovered formulas for Gaussian diffused junctions:

"C-V PARAMETER EXTRACTION TECHNIQUE FOR CHARACTERISATION OF DIFFUSED JUNCTIONS OF SEMICONDUCTOR DEVICES", presented at the International Semiconductor Conference CAS 2008, Sinaia, Romania. www.imt.ro/cas

An interesting event of 2007 was NADE with participation of Prof. C.T. Sah - by videoconference.