Abstract
The coupling between photons and electrons is at the heart of many fundamental phenomena in nature. Despite tremendous advances in controlling electrons by photons in engineered energy-band systems, control over their coupling is still widely lacking. Here we demonstrate an unprecedented ability to couple photon-electron interactions in real space, in which the incident electromagnetic wave directly tailors energy bands of solid to generate carriers for sensitive photoconductance. By spatially coherent manipulation of metal-wrapped material system through anti-symmetric electric field of the irradiated electromagnetic wave, electrons in the metals are injected and accumulated in the induced potential well (EIW) produced in the solid. Respective positive and negative electric conductances are easily observed in n-type and p-type semiconductors into which electrons flow down from the two metallic sides under light irradiation. The photoconductivity is further confirmed by sweeping the injected electrons out of the semiconductor before recombination applied by sufficiently strong electric fields. Our work opens up new perspectives for tailoring energy bands of solids and is especially relevant to develop high effective photon detection, spin injection, and energy harvesting in optoelectronics and electronics.
Highlights
The motion of electrons can be controlled by photons through band-gap engineering to solids[1]
The field-driven variation of photoconductivity by the electromagnetic wave represents an intrinsic property of the coherently coupling interaction of light wave and materials, in contrast to the special photoconductivity arising from defects[22] or spatial separation of charges by the built-in field in some heterojunctions[23]
We have firstly demonstrated the direct tailoring of photon-electron coupling for extremely sensitive photoconductivity by the injection and accumulation of electrons in the electromagnetic induced well (EIW) with excited lower energy levels, which is formed by the interaction of the anti-symmetric electric field of the irradiation with the wrapped MSM structure
Summary
The annealed samples were n-type single crystalline semiconductor with electron concentration were ne 7.3 × 1015 cm−3 and 1.5 × 1015 cm−3, as 11,000 cm2/V ⋅ s for MCT-1 and MCT-2, respectively. The ST epitaxial layer of d = 2 μm thickness was grown on glass substrate by RF sputtering method at the temperature of 250 °C with hole concentration of nh manufactured b7y.8m×icr1o0e1l9eccmtro−n3 iacnpdrhoocleessmtoebchilnitoylμohg y w96it chmg2o/Vld ⋅f silamt s30to[0] KwrbaypHthaell measurement. Mesas with fixed width of 50 μm were formed by UV photolithography process and mesa etching It left a space gap of a = 30 μm for MCT-1 and ST, and a = 5 μm for MCT-2 on the top surface of the semiconductor along x axis to form a metal-semiconductor-metal (MSM) structure. Two wires from the end of the two metallic electrodes were connected to a preamplifier, respectively
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