Indirect bandgap MoSe₂ resonators for light-emitting nanophotonics

Abstract

Transition metal dichalcogenides (TMDs) are a promising for new generation nanophotonics due to their unique optical properties. However, in contrast to direct bandgap TMDs monolayers, bulk samples have an indirect...

High‐Performance N‐MoSe2/P‐GeSn/N‐Ge van der Waals Heterojunction Phototransistor for Short‐Wave Infrared Photodetection

“…The electron affinity and bandgap of multilayer MoSe 2 are obtained from previous work. [ 20–22 ] For the partially relaxed GeSn epilayer, considering the Sn content and the degree of strain relaxation, the direct and indirect bands were calculated using the 30‐band k·p model. [ 33–35 ] According to the calculated results, the band diagram of GeSn is composed of the heavy hole valence band ($$E_{{\mathrm{V\ }}}^{{\mathrm{HH}}}$$(GeSn)), the direct conduction band minimum at the Γ valley ($$E_{{\mathrm{C\ }}}^{{\Gamma}}$$(GeSn)), and the indirect conduction band minimum at the L valley ($$E_{{\mathrm{C\ }}}^{\mathrm{L}}$$(GeSn)).…”

“…The Snrich p-GeSn epilayer greatly extends the photodetection cutoff wavelength beyond 2400 nm. The 20-nm-thick unintentionally n-doped MoSe 2 , which has a bandgap of ≈1.4 eV and an electronic affinity of ≈3.9 eV, [20][21][22] forms a type-I PN heterojunction with p-GeSn. The large bandgap offset between the n-MoSe 2 /p-Ge 0.829 Sn 0.171 heterojunction results in an ultrahigh electron/hole injection ratio, providing a high photocurrent gain for the HPT under the amplification mode (V CE > 0).…”