High performance near-infrared MoTe2/Ge heterojunction photodetector fabricated by direct growth of Ge flake on MoTe2 film substrate

Abstract

We demonstrated a feasible strategy to fabricate MoTe2/Ge heterojunction by direct growth of Ge flake on a MoTe2 film substrate with a two-step chemical vapor deposition method. A thin transition layer (∼4 nm) mainly composed of polycrystalline germanium at the MoTe2/Ge interface was verified during the Ge flake growth. The MoTe2/Ge heterojunction-based photodetector exhibits both the response speed with a rise/fall time of 7/4 μs and the photoresponsivity and detectivity with 4.87 A W−1 and 5.02 × 1011 Jones under zero bias in the near-infrared regime, respectively. The characteristics of device performance imply its practical applicability as building block for potential near-infrared integrated photonics.

Two-dimensional molybdenum ditelluride waveguide-integrated near-infrared photodetector

“…The enlarged I-V curves of the photodetector at 50 mV is displayed in figure 5 It is evident that the I ph of this device gradually increases from 2.6 nA at 800 nm to 9.7 nA at 1100 nm. This trend is due to the bandgap of the thicker MoTe 2 film close to ∼0.98 eV [2,16,23], corresponding to the peak absorption wavelength of ∼1270 nm. Therefore, the photodetector tends to increase the absorption of NIR with a wavelength of 800-1100 nm.…”

“…Near-infrared (NIR) photodetectors, as key building blocks of photonic integrated circuits, exhibit attractive potential applications in optical communications, biomedical imaging, spectroscopy, and gas sensing [1][2][3][4]. To fabricate high-performance NIR photodetectors, various narrow-bandgap semiconductor materials, such as Si, Ge, InP, InGaAs, and two-dimensional (2D) transition metal dichalcogenides (TMDCs) [5][6][7][8][9][10][11], have attracted increasing attention.…”

“…In this regard, 2D TMDCs are particularly appealing for use in photodetectors due to their high carrier mobility, broadband light absorption, mechanical flexibility, quantum confinement effect, and easy for integration [1,[12][13][14][15]. Specifically, 2Htype molybdenum ditelluride (MoTe 2 ) is considered to be one of the most ideal candidates for NIR photodetectors due to its suitably small bandgap ranging from 0.83 eV in bulk to 1.1 eV in monolayers [2,16,17]. In recent years, attempts to prepare high-performance NIR photodetectors based on MoTe 2 have aroused progressively interests.…”

“…Besides, Si 3 N 4 has a wide transmission spectrum from visible light to mid-infrared light due to the ultrawide bandgap [19]. Currently, the NIR photodetectors integrating Si 3 N 4 waveguide and 2D MoTe 2 have not yet been demonstrated.…”

Multilayer SnS2/few-layer MoS2 heterojunctions with in-situ floating photogate toward high-performance photodetectors and optical imaging application

“…Thus far, a number of 2DLMs, including graphene [15], glassy graphene [16], graphdiyne [17], chalcogenides [18][19][20][21][22][23][24][25], MXenes [26], nitrides [27], phosphides [28], metal phosphorus trichalcogenides [29], as well as related heterostructures [30][31][32][33][34][35][36][37][38][39][40], have been developed for photoelectric detection research, and these materials have manifested a variety of intriguing characteristics. For example, by exploiting low-symmetry SiP 2 nanoflake as the photosensitive channel, Wang et al [28] demonstrated a unique polarization-sensitive photodetector with a dichroic ratio of ~1.…”