Minigap-induced negative differential resistance in multilayer MoS2 -based tunnel junctions

Despite extensive research, the high-energy band properties of transition metal dichalcogenides remain unexplored. Here, we reveal that a multilayer <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:mi>Mo</a:mi><a:msub><a:mi mathvariant="normal">S</a:mi><a:mn>2</a:mn></a:msub></a:mrow></a:math>-based tunnel junction exhibits substantial negative differential resistance (NDR) owing to the presence of a minigap, which is the energy gap between the upper and lower bands of the valence band at the Γ point. We fabricated a highly <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:mi>p</c:mi></c:math>-doped multilayer <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"><d:mrow><d:msup><d:mrow><d:mi>p</d:mi></d:mrow><d:mo>+</d:mo></d:msup><d:mtext>−</d:mtext><d:mi>Mo</d:mi><d:msub><d:mi mathvariant="normal">S</d:mi><d:mn>2</d:mn></d:msub></d:mrow><d:mo>/</d:mo><d:mi>h</d:mi></d:math>-BN/<f:math xmlns:f="http://www.w3.org/1998/Math/MathML"><f:mrow><f:msup><f:mrow><f:mi>p</f:mi></f:mrow><f:mo>+</f:mo></f:msup><f:mtext>−</f:mtext><f:mi>Mo</f:mi><f:msub><f:mi mathvariant="normal">S</f:mi><f:mn>2</f:mn></f:msub></f:mrow></f:math> tunnel junction. When a bias is applied across the junction, holes at the Fermi level at the Γ point in the valence band of the source-side <h:math xmlns:h="http://www.w3.org/1998/Math/MathML"><h:mrow><h:msup><h:mrow><h:mi>p</h:mi></h:mrow><h:mo>+</h:mo></h:msup><h:mtext>−</h:mtext><h:mi>Mo</h:mi><h:msub><h:mi mathvariant="normal">S</h:mi><h:mn>2</h:mn></h:msub></h:mrow></h:math> resonantly tunnel to the drain-side <j:math xmlns:j="http://www.w3.org/1998/Math/MathML"><j:mrow><j:msup><j:mrow><j:mi>p</j:mi></j:mrow><j:mo>+</j:mo></j:msup><j:mtext>−</j:mtext><j:mi>Mo</j:mi><j:msub><j:mi mathvariant="normal">S</j:mi><j:mn>2</j:mn></j:msub></j:mrow></j:math> with momentum conservation. When the energy of the injected hole coincides with the minigap of the drain-side <l:math xmlns:l="http://www.w3.org/1998/Math/MathML"><l:mrow><l:msup><l:mrow><l:mi>p</l:mi></l:mrow><l:mo>+</l:mo></l:msup><l:mtext>−</l:mtext><l:mi>Mo</l:mi><l:msub><l:mi mathvariant="normal">S</l:mi><l:mn>2</l:mn></l:msub></l:mrow></l:math>, the tunneling conductance is suppressed; thus, NDR is observed in the current-voltage characteristics. We identified minigap-induced NDR over a broad range of <n:math xmlns:n="http://www.w3.org/1998/Math/MathML"><n:mrow><n:mi>Mo</n:mi><n:msub><n:mi mathvariant="normal">S</n:mi><n:mn>2</n:mn></n:msub></n:mrow></n:math> thicknesses, including the bulk, that was observable even at room temperature.