Effects of biased and unbiased illuminations on two-dimensional electron gases in dopant-free GaAs/AlGaAs

Article

关键词: PERSISTENT PHOTOCONDUCTIVITY;    UNDOPED HETEROSTRUCTURE;    MOBILITY ENHANCEMENT;    HOLE GASES;    DEEP DONOR;    DX-CENTER;    GAAS;    SCATTERING;    LAYERS;    TRANSPORT;   

DOI  :  10.1103/PhysRevB.105.075302

来源: SCIE

【 摘 要 】

Illumination is performed at low temperature on dopant-free two-dimensional electron gases (2DEGs) of varying depths, under unbiased (gates grounded) and biased (gates at a positive or negative voltage) conditions. Unbiased illuminations in 2DEGs located more than 70 nm away from the surface result in a gain in mobility at a given electron density, primarily driven by the reduction of background impurities. In 2DEGs closer to the surface, unbiased illuminations result in a mobility loss, driven by an increase in surface charge density. Biased illuminations performed with positive applied gate voltages result in a mobility gain, whereas those performed with negative applied voltages result in a mobility loss. The magnitude of the mobility gain (loss) weakens with 2DEG depth, and is likely driven by a reduction (increase) in surface charge density. Remarkably, this mobility gain/loss is fully reversible by performing another biased illumination with the appropriate gate voltage, provided both n-type and p-type Ohmic contacts are present. Experimental results are modeled with Boltzmann transport theory, and possible mechanisms are discussed.

【 授权许可】

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