Abstract
Spontaneous self-sustained chaotic current oscillations are observed experimentally in lightly-doped weakly-coupled GaAs/Al0.45Ga0.55As superlattices at room temperature for the first time. The mole fraction of Aluminum in the barrier is chosen to be 0.45 to suppress the thermal carrier leakage through the X-band valley. The effective nonlinearity induced by the sequential well-to-well resonant tunneling can still be strong enough to induce spontaneous chaotic current oscillations even at room temperature. The frequency spectrum of the chaotic current oscillations is ranged from DC to 4 GHz, which can be used as ultra-wide-band noise sources with a bandwidth of several Giga Hertz.
Highlights
The study of semiconductor superlattices (SLs), one of the typical low dimensional structures, has formed a major branch of solid-state physics [1]
Electrons in the center of the shrunk Brillouin zone could be drifted into the boundary that negative differential conductance (NDC) could be resulted from, which was expected to used as microwave oscillation resources with a frequency much larger than that of Gunn diodes
A lightly-doped weak-coupled SL represent as an ideal one-dimensional nonlinear dynamical system with many degrees of freedom, and the effective nonlinearity is originated from NDC
Summary
The study of semiconductor superlattices (SLs), one of the typical low dimensional structures, has formed a major branch of solid-state physics [1]. The increase of temperature would reduce the nonlinearity in weakly-coupled SLs. The nonlinearity in SLs is characterized by NDC resulted from the well-to-well sequential resonant tunneling.
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