Dynamics of electronic transport in a semiconductor superlattice with a shunting side layer

Abstract

We study a model describing electronic transport in a weakly coupled semiconductor superlattice with a shunting side layer. Key parameters include the lateral size of the superlattice, the connectivity between the quantum wells of the superlattice and the shunt layer, and the conduction properties of the shunt layer. For a superlattice with small lateral extent and high quality shunt, static electric field domains are suppressed and a spatially uniform field configuration is predicted to be stable, results that may be useful for proposed devices such as a superlattice-based terahertz oscillators. As the lateral size of the superlattice increases, the uniform field configuration loses its stability to either static or dynamic field domains regardless of shunt properties. A lower quality shunt generally leads to regular and chaotic current oscillations and complex spatiotemporal dynamics in the field profile. Bifurcations separating static and dynamic behaviors are characterized and found to be dependent on the shunt properties.

Cross-section measurements of neutron-induced reactions on GaAs using monoenergetic beams from 7.5 to 15 MeV

“…It is often preferred over other semiconductors in the construction of microwave frequency integrated circuits, infrared light-emitting diodes, laser diodes, solar cells and optical windows. It is also of significance in research related to the electronic transport and optoelectronic processes in semiconductor microstructures and nanostructures [1]. Exposure of GaAs to a flux of fast neutrons is expected to initiate transmutation processes within the semiconductor, leading to an increase in the impurity content and a consequent modification of the semiconductor properties.…”

On the possibility of a shunt-stabilized superlattice terahertz emitter

“…We have predicted shunt stabilization for structures with widths up to a few microns. In contrast, previous work showed that shunt stabilization can be effective in weakly coupled SLs with widths up to a few hundred microns, 8 a difference largely due to the much smaller vertical current densities in those structures.…”

“…14,18 We bias the structures in the NDC region, with an average field U / l = 6.67ϫ 10 6 V / m, where the total applied voltage U = 12 V is held constant and l = 1.8 m is the length of the SL in z direction. We find that excess charge associated with accumulation or depletion layers in the SL moves laterally into the shunt mainly through diffusion, 8 so the diffusion constant D Ќ needs to be sufficiently high for the field to be stabilized. Since D Ќ = k B T / e , we can enhance the diffusion process by working at room temperature, T = 300 K. We assume a mobility =2 m 2 / Vs, achievable using InAs quantum wells.…”

“…7 Recently, we showed that a side shunting layer can stabilize a spatially uniform, time-independent electric field in weakly coupled SLs, provided that the lateral width of the SL-i.e., the spatial extent in the direction parallel to the quantum wells-is not too large. 8 In this case, the transport occurs as sequential resonant tunneling of electrons between successive quantum wells. 9 However, Bloch oscillations are expected for strongly-coupled SLs in which electronic transport occurs via miniband conduction.…”

“…9 However, Bloch oscillations are expected for strongly-coupled SLs in which electronic transport occurs via miniband conduction. 10,11 Here, we adapt the method for treating lateral dynamics in weakly coupled SLs 8,12,13 to model transport in a strongly coupled SL with a shunting layer.…”