MoTe₂ PN Homojunction Constructed on a Silicon Photonic Crystal Cavity for High-Performance Photodetector

Abstract

We demonstrate a straightforward construction of MoTe2 PN homojunction on a silicon photonic crystal cavity, which promises the realizations of cavity-enhanced optoelectronic devices integrated on silicon photonic chips. The employed silicon photonic crystal cavity has an air-slot in the middle to split it into two parts, which directly function as two individual back-gate electrodes of the top-coated few-layer MoTe2. Beneficial from MoTe2’s ambipolar property, reconfigured (PN, NN, PP, NP) homojunctions are realized by controlling the gate voltages of the two separated silicon electrodes. For instance, on/off ratios exceeding 104 are obtained from the PN or NP homojunctions, and the ideality factors could approach 1.00. On the other hand, the silicon photonic crystal cavity could enhance light absorption in the coated MoTe2, promising high-performance photodetection. By coupling the resonant mode with the MoTe2 PN junction, a high photoresponsivity of 156 mA/W is obtained at the wavelength of 1353.7 nm, though it is the limit of MoTe2’s absorption bandedge. As attributes of the PN junction, the photodetector has a dark current as low as 0.14 nA and a response bandwidth exceeding 1.1 GHz. The proposed device geometry has advantages of employing silicon photonic crystal cavity as the back gates of MoTe2 PN junction directly and simultaneously to enhance light–MoTe2 interactions, which might open a new avenue to construct MoTe2-based laser diodes and electro-optic modulators on silicon photonic chips.

Reconfigurable InSe Electronics with van der Waals Integration

“…The photodetection performance of the device is comparable to other p-n homojunction photodiodes based on 2D semiconductors, such as WSe 2 and MoTe 2 . [17,18,22] In Figure S3 (Supporting Information), we present the short-circuit current I sc , open-circuit voltage V oc , power conversion efficiency γ, and fill factor FF of the InSe p-n diode as a function of incident laser power. The conversion efficiency of γ ≈ 2.3% and the fill factor of FF ≈ 0.38 are obtained, respectively.…”

“…[ 8–12 ] Gate‐tunable polarity has been implemented with a few 2D semiconductors such as black phosphorus and some transition metal dichalcogenides, [ 13–16 ] which enable reconfigurable field‐effect transistors (FETs) and p–n diodes with a simple dual‐gate structure that boost the development of digital technology and complementary electronics. [ 17–22 ]…”

“…[8][9][10][11][12] Gatetunable polarity has been implemented with a few 2D semiconductors such as black phosphorus and some transition metal dichalcogenides, [13][14][15][16] which enable reconfigurable field-effect transistors (FETs) and p-n diodes with a simple dual-gate structure that boost the development of digital technology and complementary electronics. [17][18][19][20][21][22] Indium selenide (InSe) is a layered metal-chalcogenide semiconductor assembled by van der Waals (vdW) interactions. Atoms in each InSe layer (≈0.8 nm thick) are close-packed in the Se-In-In-Se atomic sequence.…”

Electrically Tunable Second Harmonic Generation in Atomically Thin ReS2

“…Two Au electrodes with a thickness of 100 nm were then transferred on the ReS2 flake acting as the drain and source electrodes. [25][26][27][28][29] The heavily doped Si substrate could function as a bottom electrical gate. By applying an electrical voltage between the heavily doped Si substrate and the source electrode, i.e.…”

2D materials-enabled optical modulators: From visible to terahertz spectral range

“…[3][4][5] Recently, two-dimensional (2D) materials with layered structures have emerged as an attractive active medium for constructing optoelectronic devices. [6][7][8][9][10][11][12][13][14] It has been reported that versatile single-elementary and compound materials have layered stacking forms, which could be exfoliated into a 2D material with a thickness of few-atom layer. Therefore, plentiful electrical, optical, magnetic, and mechanical properties could be acquired from 2D materials.…”