We report on the first demonstration of p-type doping in large area few-layer films of (0001)-oriented chemical vapor deposited (CVD) MoS 2 . Niobium was found to act as an efficient acceptor up to relatively high density in MoS 2 films. For a hole density of 4 x 10 20 cm -3Hall mobility of 8.5 cm 2 V -1 s -1 was determined, which matches well with the theoretically expected values. XRD and Raman characterization indicate that the film had good out-of-plane crystalline quality. Absorption measurements showed that the doped sample had similar characteristics to high-quality undoped samples, with a clear absorption edge at 1.8 eV. This demonstration of p-doping in large area epitaxial MoS 2 could help in realizing a wide variety of electrical and opto-electronic devices based on layered metal dichalcogenides.
We report on the vapor-solid growth of single crystalline few-layer MoS2 films on (0001)-oriented sapphire with excellent structural and electrical properties over centimeter length scale. Highresolution X-ray diffraction scans indicated that the films had good out-of-plane ordering and epitaxial registry. A carrier density of ~2 x 10 11 cm -2 and a room temperature mobility of 192 cm 2 /Vs were extracted from space-charge limited transport regime in the films. The electron mobility was found to exhibit in-plane anisotropy with a ratio of ~ 1.8. Theoretical estimates of the temperature-dependent electron mobility including optical phonon, acoustic deformation potential and remote ionized impurity scattering were found to satisfactorily match the measured data. The synthesis approach reported here demonstrates the feasibility of device quality few-layer MoS2 films with excellent uniformity and high quality.
Electrical and optical characterization of two-dimensional/three-dimensional (2D/3D) pmolybdenum disulfide/n-gallium nitride (p-MoS 2 /n-GaN) heterojunction diodes are reported.Devices were fabricated on high-quality, large-area p-MoS 2 grown by chemical vapor deposition (CVD) on hexagonal sapphire substrates. The processed devices were transferred onto GaN/sapphire substrates, and the transferred films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). On-axis XRD spectra and surface topology
The growth and electrical characterization of the heterojunction formed between two-dimensional (2D) layered p-molybdenum disulfide (MoS 2 ) and nitrogen-doped 4H silicon carbide (SiC) are reported. The integration of 2D semiconductors with the conventional three-dimensional (3D) substrates could enable semiconductor heterostructures with unprecedented properties. In this work, direct growth of p-type MoS 2 films on SiC was demonstrated using chemical vapor deposition, and the MoS 2 films were found to be high quality based on x-ray diffraction and Raman spectra. The resulting heterojunction was found to display rectification and current-voltage characteristics consistent with a diode for which forward conduction in the low-bias region is dominated by multistep recombination tunneling. Capacitance-voltage measurements were used to determine the built-in voltage for the p-MoS 2 /n-SiC heterojunction diode, and we propose an energy band line up for the heterostructure based on these observations. The demonstration of heterogeneous material integration between MoS 2 and SiC enables a promising new class of 2D/3D heterostructures. V C 2014 AIP Publishing LLC. [http://dx.
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