Gate tunable p-n heterojunction diode

NU 2013-107

Inventors

Mark C. Hersam*

Deep M. Jariwala

Vinod K. Sangwan

Short Description

Gate tunable p-n heterojunction diode NU2013-107 A gate-tunable p-n heterojunction semiconductor composed of single-walled carbon nanotubes and single-layer molybdenum disulphide that could be widely-generalized to a variety of ultrathin, high-performance electronics and optoelectronics.

Abstract

Northwestern researchers have created a gate-tunable p-n heterojunction diode. This invention addresses a need for a p-n heterojunction diode derived from ultrathin materials that could be used in complex electronic and optoelectronic circuits. The new diode structure uses semiconducting single-walled carbon nanotubes (s-SWCNTs) and single-layer molybdenum disulphide (SL-MoS2) as p-type and n-type semiconductors, respectively (Figure). The vertical stacking of these two direct band gap semiconductors forms a heterojunction with electrical characteristics that can be tuned with an applied gate bias over a wide range of charge transport behavior. Tuning ability ranges from insulating to rectifying with forward-to-reverse bias current ratios exceeding 104. This heterojunction diode also responds strongly to optical irradiation with an external quantum efficiency (EQE) of 25% and fast photoresponse < 15 μs. Because SWCNTs have a diverse range of electrical properties as a function of chirality and an increasing number of atomically thin 2D nanomaterials are being isolated, the gate-tunable p-n heterojunction presented here should be widely generalizable to realize diverse ultrathin, high performance electronics and optoelectronics. [FIGURE NEEDS TO BE IMPORTED SEPARATELY] Figure: Microscopy and fabrication of the s-SWCNTs/SL-MoS2 p-n heterojunction diode. a) False-colored SEM image of the heterojunction diode (scale bar = 2.5 μm). The yellow gold electrodes, alumina blue region insulating a portion of the SL-MoS2 flake, violet region. Pink region is random network of s-SWCNTs (p-type) in direct contact with the exposed SL-MoS2 flake (n-type) to form the p-n heterojunction diode (dark red). b) Optical micrograph showing the device layout at a lower magnification. c) Schematic of the fabrication process:

Applications

• Ultrathin, high-performance electronics and optoelectronics circuits and devices

Advantages

• Integrated p-type s-SWCNTs and n-type SL-MoS2 to form a heterojunction diode
• Wide tunability of charge transport from insulating state to a highly rectifying condition
• As a three-terminal device, the p-n heterojunction diode exhibits 'anti-ambipolar' behavior suggesting utility in advanced logic applications
• The p-n heterojunction diode serves as an effective photodetector with fast photoresponse

Publication

Jariwala D, et al. Gate-tunable carbon nanotube–MoS2 heterojunction p-n diode (2013). Proceedings of the National Academy of Sciences of the United States of America. 2013:110(45); 18076-18080.

IP Status

A US patent application has been filed.