title: Enabling Ultrasensitive Photo-detection Through Control of Interface Properties in Molybdenum Disulfide Atomic Layers.
abstract: The interfaces in devices made of two-dimensional materials such as MoS2can effectively control their optoelectronic performance. However, the extent and nature of these deterministic interactions are not fully understood. Here, we investigate the role of substrate interfaces on the photodetector properties of MoS2devices by studying its photocurrent properties on both SiO2and self-assembled monolayer-modified substrates. Results indicate that while the photoresponsivity of the devices can be enhanced through control of device interfaces, response times are moderately compromised. We attribute this trade-off to the changes in the electrical contact resistance at the device metal-semiconductor interface. We demonstrate that the formation of charge carrier traps at the interface can dominate the device photoresponse properties. The capture and emission rates of deeply trapped charge carriers in the substrate-semiconductor-metal regions are strongly influenced by exposure to light and can dynamically dope the contact regions and thus perturb the photodetector properties. As a result, interface-modified photodetectors have significantly lower dark-currents and higher on-currents. Through appropriate interfacial design, a record high device responsivity of 4.5 × 103A/W at 7 V is achieved, indicative of the large signal gain in the devices and exemplifying an important design strategy that enables highly responsive two-dimensional photodetectors.
authors.affiliation: United States Army Research Laboratories, Sensors and Electron Devices Directorate, 2800 Powder Mill Road, Adelphi, Maryland 20783, USA.
authors.forename: Sina
authors.initials: S
authors.lastname: Najmaei
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA.
authors.forename: Sidong
authors.initials: S
authors.lastname: Lei
authors.affiliation: United States Army Research Laboratories, Sensors and Electron Devices Directorate, 2800 Powder Mill Road, Adelphi, Maryland 20783, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Burke
authors.affiliation: United States Army Research Laboratories, Sensors and Electron Devices Directorate, 2800 Powder Mill Road, Adelphi, Maryland 20783, USA.
authors.forename: Barbara M
authors.initials: BM
authors.lastname: Nichols
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA.
authors.forename: Antony
authors.initials: A
authors.lastname: George
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA.
authors.forename: Pulickel M
authors.initials: PM
authors.lastname: Ajayan
authors.affiliation: Department of Electrical &Computer Engineering, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Aaron D
authors.initials: AD
authors.lastname: Franklin
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Lou
authors.affiliation: United States Army Research Laboratories, Sensors and Electron Devices Directorate, 2800 Powder Mill Road, Adelphi, Maryland 20783, USA.
authors.forename: Madan
authors.initials: M
authors.lastname: Dubey