Bifunctional ultraviolet light-emitting/detecting device based on a SnO₂ microwire/p-GaN heterojunction

Abstract

<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m1"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>SnO</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:math> has attracted considerable attention due to its wide bandgap, large exciton binding energy, and outstanding electrical and optoelectronic features. Owing to the lack of reliable and reproducible p-type <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m2"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>SnO</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:math> , many challenges on developing <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m3"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>SnO</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:math> -based optoelectronic devices and their practical applications still remain. Herein, single-crystal <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m4"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>SnO</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:math> microwires (MWs) are acquired via the self-catalyzed approach. As a strategic alternative, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m5"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">n</mml:mi> <mml:mtext>-</mml:mtext> <mml:mi>SnO</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> MW/p-GaN heterojunction was constructed, which exhibited selectable dual-functionalities of light-emitting and photodetection when operated by applying an appropriate voltage. The device illustrated a distinct near-ultraviolet light-emission peaking at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m6"> <mml:mrow> <mml:mo form="prefix">∼</mml:mo> <mml:mn>395.0</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>nm</mml:mi> </mml:mrow> </mml:math> and a linewidth <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m7"> <mml:mrow> <mml:mo form="prefix">∼</mml:mo> <mml:mn>50</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>nm</mml:mi> </mml:mrow> </mml:math> . Significantly, the device characteristics, in terms of the main peak positions and linewidth, are nearly invariant as functions of various injection current, suggesting that quantum-confined Stark effect is essentially absent. Meanwhile, the identical <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m8"> <mml:mrow> <mml:mi mathvariant="normal">n</mml:mi> <mml:mtext>-</mml:mtext> <mml:msub> <mml:mrow> <mml:mi>SnO</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> MW/p-GaN heterojunction can also achieve photovoltaic-type light detection. The device can steadily feature ultraviolet photodetecting ability, including the ultraviolet/visible rejection ratio ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m9"> <mml:msub> <mml:mi>R</mml:mi> <mml:mrow> <mml:mn>360</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>nm</mml:mi> </mml:mrow> </mml:msub> <mml:mo>/</mml:mo> <mml:msub> <mml:mi>R</mml:mi> <mml:mrow> <mml:mn>400</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>nm</mml:mi> </mml:mrow> </mml:msub> </mml:math> ) <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m10"> <mml:mrow> <mml:mo form="prefix">∼</mml:mo> <mml:mn>1.5</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mn>3</mml:mn> </mml:msup> </mml:mrow> </mml:math> , high photodark current ratio of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m11"> <mml:mrow> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mn>5</mml:mn> </mml:msup> </mml:mrow> </mml:math> , fast response speed of 9.2/51 ms, maximum responsivity of 1.5 A/W, and detectivity of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m12"> <mml:mrow> <mml:mn>1.3</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>13</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> Jones under 360 nm light at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m13"> <mml:mrow> <mml:mo form="prefix">−</mml:mo> <mml:mn>3</mml:mn> <mml:mtext> </mml:mtext> <mml:mi mathvariant="normal">V</mml:mi> </mml:mrow> </mml:math> bias. Therefore, the bifunctional device not only displays distinct near-ultraviolet light emission, but also has the ability of high-sensitive ultraviolet photodetection. The novel design of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m14"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">n</mml:mi> <mml:mtext>-</mml:mtext> <mml:mi>SnO</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> MW/p-GaN heterojunction bifunctional systems is expected to open doors to practical application of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m15"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>SnO</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:math> microstructures/nanostructures for large-scale device miniaturization, integration and multifunction in next-generation high-performance photoelectronic devices.

Topics & Concepts