Lateral Surface Superlattices and Quasi-One-Dimensional Structures in GaAs
Two types of field-effect transistors on a modulation-doped GaAs/GaA1As heterostructure will be discussed. The first type has a gate electrode that consists of a 0.2 µm-period Ti/Au grid which presents a tunable, two-dimensional periodic potential modulation (lateral surfacesuperlattice, LSSL) to electrons traveling from source to drain. The other type consists of 100 parallel GaAs/GaAlAs channels, each about 40 nm-wide where the electron density is controlled by backgate bias or illumination. Conductance measurements at 4.2 K exhibit clearly a super-lattice effect (i.e., coherent back-diffraction) and provide evidence of sequential resonant tunneling in the LSSL-type device. Similar measurements show clear evidence of quasi-one-dimensional (Q1D) density of states and corresponding electron mobility modulation in the Q1D type devices.
KeywordsFermi Energy Substrate Bias Gate Bias Negative Differential Resistance AlGaAs Layer
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