Semiconductor Research Corp., Research Triangle Park, N.C., reports that a team of researchers from Purdue University, Lafayette, Ind.; SEMATECH, Albany, N.Y.; and SUNY College of Nanoscale Science and Engineering, Albany, N.Y., are working on high-performance molybdenum disulfide field-effect transistors. The team’s research is an important milestone for the realization of the ultra-scaled low-power 2D MoS2 FETs and the advancement of photonic and electronic devices such as solar cells, phototransistors and low-power logic FETs. Based on transition metal dichalcogenide materials, the research is supported by Semiconductor Research Corporation (SRC) and SEMATECH.
As part of the research, the team leveraged MoS2, which has been studied closely in recent years by the semiconductor industry due to its potential applications in electrical and optical devices. However, high contact resistance value limits the device performance of MoS2 FETs significantly. One method to resolve this issue is to dope the MoS2 film, but doping the atomically thin film is not trivial, and requires a simple and reliable process technique. The technique used by the research team provides an effective and straightforward way to dope the MoS2 film with chloride-based chemical doping, and significantly reduces the contact resistance.
“Compared with other chemical doping materials such as PEI (polyethylene imine) and potassium, our doping technology shows superior transistor performance including higher drive current, higher on/off current ratio and lower contact resistance,” said Professor Peide Ye, College of Engineering, Purdue University.
In order to obtain high-performance FETs, three parts of the device should be carefully engineered: semiconductor channel (carrier density and its mobility); semiconductor-oxide interface; and semiconductor-metal contact. This research is particularly aimed at eliminating the last major roadblock toward demonstration of high-performance MoS2 FETs, namely, high contact resistance.
The MoS2 FETs made via the doping technique were fabricated at Purdue University, but can be reproduced now in a semiconductor manufacturing environment and show the best electrical performance among all the reported TMD-based FETs. The contact resistance (0.5 kΩ·μm) with the doping technique is ten times lower than the controlled samples. The drive current (460 μA/μm) is twice the best value reported in previous literature.
