Biomedical subjects

R Escobedo

Publications and source records attributed to R Escobedo.

3 recordsLinked to original sources

PubMed2003

Free-boundary problems describing two-dimensional pulse recycling and motion in semiconductors.

An asymptotic analysis of the Gunn effect in two-dimensional samples of bulk n GaAs with circular contacts is presented. A moving pulse far from contacts is approximated by a moving free boundary separating regions where the electric potential solves a Laplace equation with subsidiary boundary conditions. The dynamical condition for the motion of the free boundary is a Hamilton-Jacobi equation. We obtain the exact solution of the free-boundary problem (FBP) in simple one-dimensional and axisymmetric geometries. The solution of the FBP is obtained numerically in the general case and compared with the numerical solution of the full system of equations. The agreement is excellent so that the FBP can be adopted as the basis for an asymptotic study of the multidimensional Gunn effect.

Journal Article↗

PubMed2001

Axisymmetric pulse recycling and motion in bulk semiconductors.

The Kroemer model for the Gunn effect in a circular geometry (Corbino disks) has been numerically solved. The results have been interpreted by means of asymptotic calculations. Above a certain onset dc voltage bias, axisymmetric pulses of the electric field are periodically shed by an inner circular cathode. These pulses decay as they move towards the outer anode, which they may not reach. As a pulse advances, the external current increases continuously until a new pulse is generated. Then the current abruptly decreases, in agreement with existing experimental results. Depending on the bias, more complex patterns with multiple pulse shedding are possible.

Journal Article↗

PubMed2001

Two-dimensional oscillatory patterns in semiconductors with point contacts.

Planar samples of n-GaAs with attached point contacts at different dc voltages may display a variety of spatiotemporal patterns arising from the dynamics of curved charge dipole waves. Patterns rank from oscillations due to recycling and motion of simple quasiplanar or cylindrical wave fronts to more complex patterns that include merging and splitting of different fronts. Results of numerical simulations are interpreted by means of simple one-dimensional asymptotic theories.

Journal Article↗