silicon and molybdenum-disulfide

A phototransistor based on a chemical vapor deposited (CVD) MoS2 monolayer exhibits a high photoresponsivity (2200 A W(-1) ) and an excellent photogain (5000). The presence of shallow traps contributes to the persistent photoconductivity. Ambient adsorbates act as p-dopants to MoS2 , decreasing the carrier mobility, photoresponsivity, and photogain.

Topics: Disulfides; Electric Conductivity; Light; Molybdenum; Silicon; Silicon Dioxide; Transistors, Electronic; Volatilization

One important use of layered semiconductors such as molybdenum disulfide (MoS2) could be in making novel heterojunction devices leading to functionalities unachievable using conventional semiconductors. Here we demonstrate a metal-semiconductor-metal heterojunction photodetector, made of MoS2 and amorphous silicon (a-Si), with rise and fall times of about 0.3 ms. The transient response does not show persistent (residual) photoconductivity, unlike conventional a-Si devices where it may last 3-5 ms, thus making this heterojunction roughly 10X faster. A photoresponsivity of 210 mA/W is measured at green light, the wavelength used in commercial imaging systems, which is 2-4X larger than that of a-Si and best reported MoS2 devices. The device could find applications in large area electronics, such as biomedical imaging, where a fast response is critical.

Topics: Disulfides; Dose-Response Relationship, Radiation; Equipment Design; Equipment Failure Analysis; Molybdenum; Photometry; Radiation Dosage; Semiconductors; Silicon

Two-dimensional materials are attractive for use in next-generation nanoelectronic devices because, compared to one-dimensional materials, it is relatively easy to fabricate complex structures from them. The most widely studied two-dimensional material is graphene, both because of its rich physics and its high mobility. However, pristine graphene does not have a bandgap, a property that is essential for many applications, including transistors. Engineering a graphene bandgap increases fabrication complexity and either reduces mobilities to the level of strained silicon films or requires high voltages. Although single layers of MoS(2) have a large intrinsic bandgap of 1.8 eV (ref. 16), previously reported mobilities in the 0.5-3 cm(2) V(-1) s(-1) range are too low for practical devices. Here, we use a halfnium oxide gate dielectric to demonstrate a room-temperature single-layer MoS(2) mobility of at least 200 cm(2) V(-1) s(-1), similar to that of graphene nanoribbons, and demonstrate transistors with room-temperature current on/off ratios of 1 × 10(8) and ultralow standby power dissipation. Because monolayer MoS(2) has a direct bandgap, it can be used to construct interband tunnel FETs, which offer lower power consumption than classical transistors. Monolayer MoS(2) could also complement graphene in applications that require thin transparent semiconductors, such as optoelectronics and energy harvesting.

Topics: Disulfides; Equipment Design; Graphite; Microscopy, Atomic Force; Molybdenum; Nanostructures; Nanotechnology; Nanotubes, Carbon; Semiconductors; Silicon; Silicon Dioxide; Surface Properties; Temperature; Transistors, Electronic

Topics: Disulfides; Electronics; Graphite; Hafnium; Molybdenum; Nanostructures; Nanotechnology; Radio Frequency Identification Device; Semiconductors; Silicon; Silicon Dioxide; Sulfur; Surface Properties; Transistors, Electronic