Project TitleGate tunable p-n heterojunction diode
Track Code2013-107
Short Description

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.

#materials #semiconductor #cnt #devices #optoelectronic #electronic


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: 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

TagsDEVICES: optoelectronic, MATERIALS: CNT, MATERIALS: electronic, MATERIALS: semiconductor
Posted DateMay 15, 2014 2:47 PM


Mark C. Hersam*
Deep M. Jariwala

Vinod K. Sangwan


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


  • 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


IP Status

A US patent application has been filed.

Contact Information

Arjan Quist, Ph.D.
Invention Manager  

(p) (847) 467-0305



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