(Physicist, MBA)

- Investigation of hot electrons by Evolutionary
Algorithms

- Mutation-Operator-Monte-Carlo-method (MOMC)

- Local-Iterative-Monte-Carlo-method (LIMO)

- Monte-Carlo simulation of the Quantum-State-Transfer (QST)

## Investigation of hot electrons with the aid of Evolutionary Algorithms

By means of Evolutionary Algorithms, a class of robust optimization techniques used in Operations Research, it is possible to backward calculate electron distributions from measurement results.**HgCdTe**

The observation of EEW in HgCdTe makes it possible to investigate the electric field distribution of electrons in this material for T<30 K. EAs revealed that in order to achieve energy balance in moderate electric fields, the electron distribution differs slightly from a Fermi distribution.

-*Genetic algorithms: A new approach to energy balance equations*, J. Jakumeit, Appl. Phys. Lett. 66, 1812, 1995**Silizium (Si-MOSFETs)**

In collaboration with the group of Prof. K. Hess and Prof. U. Ravaioli at the Beckman Institut of the University of Illinois ( National Center for Computational Electronics) the EAs were used to investigate the distribution of hot electrons in silicon. The object was to calculate sustrate and gate currents in Si-MOSFETs. With help of a physical mutation operator, which is based on the Monte-Carlo technique, results comparable to full band calculations could be obtained.

-*Calculation of hot electron distributions in silicon by means of an Evolutionary Algorithm*, J. Jakumeit, U.~Ravaioli, K.~Hess, J. Appl. Phys., Okt. 96, (postscript, gezipt, 153kb)

-*Evolutionary algorithms for the calculation of electron distributions in Si-MOSFETs*, J, Jakumeit, Proceedings of the IV. International Conference on Parallel Problem Solving from Nature (Berlin 1996), Lecture Notes in Computer Science 1141, Springer Verlag, 1996, S. 819 (postscript, gezipt, 186kb)

## Mutation-Operator-Monte-Carlo method (MOMC)

An important part of the quasi backward calculation of electron distributions by EAs is the physic based mutation. Calling the physical mutation operator without using the optimization of the EA leads to a new type of Monte-Carlo technique, the Mutation-Operator-Monte-Carlo method (MOMC). For the calculation of the distribution of hot electrons in bulk silicon a better resolution of the high energy tail of the distribution could be obtained by the new method when compared to a Full-Band-Monte-Carlo-simulation. The MOMC requires also less time to compute.

-*Simulation of Si-MOSFETs with the Mutation Operator Monte Carlo Method*,J. Jakumeit, A. Duncan, U. Ravaioli, K. Hess, Proceedings of the 5th International Workshop on Computational Electronics (Notre Dame 1997), to be published in VLSI-Design

## Local-Iterative-Monte-Caro-Technik (LIMO)

The combination of many short and therefore local Monte Carlo steps with and iteration process leads to the local iterative Monte Carlo technique (LIMO). This new approach results in a isotropic distribution of the computation time over the phase space, so that regions with low carrier density are simulated with the same accuracy as those regions with high density. The computation time can significantly be reduced by memorizing the results of many local Monte Carlo steps in a drift table. The LIMO technique can easily be combined with an evolutionary optimization algorithm.

The LIMO technique with and without optimization is base of the ELIMO-package for the simulation of silicon and Si-MOSFETs. The package includes all necessary informations and the source codes for a test of this new Monte Carlo technique as well as some examples.

-*Iterative Local Monte Carlo Technique for the Simulation of Si-MOSFETs*,J. Jakumeit, T. Sontowski, U. Ravaioli, Proceedings of the 6th International Workshop on Computational Electronics (Osaka 1998), to be published in VLSI-Design (postscript, gezipt, 63 kb)

- ELIMO-package (getart, gezipt, 2.7 Mb)

## Monte-Carlo simulation of the Quantum-State-Transfer (QST)

The QST is a special form of the Real-Space-Transfers, using quantum mechanical tunneling of hot electrons between quantum wells with different mobilities. While performing research with the group of Prof. D. Pavlidis at the University of Michigan, I investigated the possibilities and limits of the QST by means of the Monte-Carlo technique. .

-*Quantum state transfer in double-quantum-well devices*, Jakumeit*et al.*, J. Appl. Phys. 76, 7428, 1994