Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Unipolar barrier photodetectors based on van der Waals heterostructures


Unipolar barrier structures are used to suppress dark current in photodetectors by blocking majority carriers. Designing unipolar barriers with conventional materials is challenging due to the strict requirements of lattice and band matching. Two-dimensional materials have self-passivated surfaces and tunable band structures, and can thus be used to design unipolar barriers in which lattice mismatch and interface defects are avoided. Here, we show that band-engineered van der Waals heterostructures can be used to build visible and mid-wavelength infrared unipolar barrier photodetectors. Our nBn unipolar barrier photodetectors, which are based on a tungsten disulfide/hexagonal boron nitride/palladium diselenide heterostructure, exhibit a low dark current of 15 pA, a photocurrent of 20 μA and a detectivity of 2.7 × 1012 cm Hz1/2 W−1. Our pBp unipolar barrier photodetectors, which are based on a black phosphorus/molybdenum disulfide/graphene heterostructure, exhibit a room-temperature detectivity of 2.3 × 1010 cm Hz1/2 W−1 in the mid-wavelength infrared region under blackbody radiation. The pBp devices also show a dichroic ratio of 4.9 under blackbody radiation, and a response time of 23 μs under 2 μm laser illumination.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Band diagrams and dark-current mechanisms of unipolar barrier photodetectors.
Fig. 2: Optoelectronic characteristics of nBn vdW unipolar barrier photodetectors at room temperature.
Fig. 3: Optoelectronic characteristics of pBp vdW unipolar barrier MWIR photodetectors at room temperature.
Fig. 4: Performance comparison of the vdW unipolar barrier photodetectors with previous photodetectors at room temperature.

Data availability

Data that support the findings of this study are available from the corresponding authors upon reasonable request. Source data are provided with this paper.


  1. 1.

    Martyniuk, P., Kopytko, M. & Rogalski, A. Barrier infrared detectors. Opto-Electron. Rev. 22, 127–146 (2014).

    Google Scholar 

  2. 2.

    Maimon, S. & Wicks, G. W. nBn detector, an infrared detector with reduced dark current and higher operating temperature. Appl. Phys. Lett. 89, 151109 (2006).

    Google Scholar 

  3. 3.

    Kim, H. S. et al. Long-wave infrared nBn photodetectors based on InAs/InAsSb type-II superlattices. Appl. Phys. Lett. 101, 159 (2012).

    Google Scholar 

  4. 4.

    Kopytko, M. & Rogalski, A. HgCdTe barrier infrared detectors. Prog. Quantum Electron. 47, 1–18 (2016).

    Google Scholar 

  5. 5.

    Lei, W., Antoszewski, J. & Faraone, L. Progress, challenges, and opportunities for HgCdTe infrared materials and detectors. Appl. Phys. Rev. 2, 041303 (2015).

    Google Scholar 

  6. 6.

    Xia, F., Wang, H., Xiao, D., Dubey, M. & Ramasubramaniam, A. Two-dimensional material nanophotonics. Nat. Photon. 8, 899–907 (2014).

    Google Scholar 

  7. 7.

    Liu, C. et al. Two-dimensional materials for next-generation computing technologies. Nat. Nanotechnol. 15, 545–557 (2020).

    Google Scholar 

  8. 8.

    Liu, Y., Huang, Y. & Duan, X. Van der Waals integration before and beyond two-dimensional materials. Nature 567, 323–333 (2019).

    Google Scholar 

  9. 9.

    Li, L. et al. Direct observation of the layer-dependent electronic structure in phosphorene. Nat. Nanotechnol. 12, 21–25 (2017).

    Google Scholar 

  10. 10.

    Guo, Q. et al. Efficient electrical detection of mid-infrared graphene plasmons at room temperature. Nat. Mater. 17, 986–992 (2018).

    Google Scholar 

  11. 11.

    Deng, B. et al. Strong mid-infrared photoresponse in small-twist-angle bilayer graphene. Nat. Photon. 14, 549–553 (2020).

    Google Scholar 

  12. 12.

    Chen, X. et al. Widely tunable black phosphorus mid-infrared photodetector. Nat. Commun. 8, 1672 (2017).

    Google Scholar 

  13. 13.

    Youngblood, N., Chen, C., Koester, S. J. & Li, M. Waveguide-integrated black phosphorus photodetector with high responsivity and low dark current. Nat. Photon. 9, 247–252 (2015).

    Google Scholar 

  14. 14.

    Huang, M. et al. Multifunctional high-performance van der Waals heterostructures. Nat. Nanotechnol. 12, 1148–1154 (2017).

    Google Scholar 

  15. 15.

    Tu, L. et al. Ultrasensitive negative capacitance phototransistors. Nat. Commun. 11, 101 (2020).

    Google Scholar 

  16. 16.

    Yu, X. et al. Atomically thin noble metal dichalcogenide: a broadband mid-infrared semiconductor. Nat. Commun. 9, 1545 (2018).

    Google Scholar 

  17. 17.

    Amani, M., Regan, E., Bullock, J., Ahn, G. H. & Javey, A. Mid-wave infrared photoconductors based on black phosphorus–arsenic alloys. ACS Nano 11, 11724–11731 (2017).

    Google Scholar 

  18. 18.

    Buscema, M. et al. Fast and broadband photoresponse of few-layer black phosphorus field-effect transistors. Nano Lett. 14, 3347–3352 (2014).

    Google Scholar 

  19. 19.

    Wu, F. et al. High efficiency and fast van der Waals hetero-photodiodes with a unilateral depletion region. Nat. Commun. 10, 4663 (2019).

    Google Scholar 

  20. 20.

    Gao, A. et al. Observation of ballistic avalanche phenomena in nanoscale vertical InSe/BP heterostructures. Nat. Nanotechnol. 14, 217–222 (2019).

    Google Scholar 

  21. 21.

    Fu, Q. et al. Ultrasensitive 2D Bi2O2Se phototransistors on silicon substrates. Adv. Mater. 31, 1804945 (2019).

    Google Scholar 

  22. 22.

    Suh, J. et al. Reconfiguring crystal and electronic structures of MoS2 by substitutional doping. Nat. Commun. 9, 199 (2018).

    Google Scholar 

  23. 23.

    Zhao, Y. et al. Doping, contact and interface engineering of two-dimensional layered transition metal dichalcogenides transistors. Adv. Funct. Mater. 27, 1603484 (2017).

    Google Scholar 

  24. 24.

    Savich, G. R., Pedrazzani, J. R., Sidor, D. E., Maimon, S. & Wicks, G. W. Dark current filtering in unipolar barrier infrared detectors. Appl. Phys. Lett. 99, 121112 (2011).

    Google Scholar 

  25. 25.

    Savich, G. R., Pedrazzani, J. R., Sidor, D. E. & Wicks, G. W. Benefits and limitations of unipolar barriers in infrared photodetectors. Infrared Phys. Technol. 59, 152–155 (2013).

    Google Scholar 

  26. 26.

    Chow, W. L. et al. High mobility 2D palladium diselenide field-effect transistors with tunable ambipolar characteristics. Adv. Mater. 29, 1602969 (2013).

    Google Scholar 

  27. 27.

    Shi, Z. et al. Vapor–liquid–solid growth of large-area multilayer hexagonal boron nitride on dielectric substrates. Nat. Commun. 11, 849 (2020).

    Google Scholar 

  28. 28.

    Hong, X. et al. Ultrafast charge transfer in atomically thin MoS2/WS2 heterostructures. Nat. Nanotechnol. 9, 682–686 (2014).

    Google Scholar 

  29. 29.

    Sun, J. et al. Lateral 2D WSe2 p–n homojunction formed by efficient charge-carrier-type modulation for high-performance optoelectronics. Adv. Mater. 32, 1906499 (2020).

    Google Scholar 

  30. 30.

    Li, L. et al. Black phosphorus field-effect transistors. Nat. Nanotechnol. 9, 372–377 (2014).

    Google Scholar 

  31. 31.

    Martyniuk, P., Gawron, W. & Rogalski, A. Theoretical modeling of HOT HgCdTe barrier detectors for the mid-wave infrared range. J. Electron. Mater. 42, 3309–3319 (2013).

    Google Scholar 

  32. 32.

    Itsuno, A. M., Phillips, J. D. & Velicu, S. Design and modeling of HgCdTe nBn detectors. J. Electron. Mater. 40, 1624–1629 (2011).

    Google Scholar 

  33. 33.

    Kuzum, D. et al. Transparent and flexible low noise graphene electrodes for simultaneous electrophysiology and neuroimaging. Nat. Commun. 5, 5259 (2014).

    Google Scholar 

  34. 34.

    Wang, J. et al. High mobility MoS2 transistor with low Schottky barrier contact by using atomic thick h-BN as a tunneling layer. Adv. Mater. 28, 8302–8308 (2016).

    Google Scholar 

  35. 35.

    Yuan, H. et al. Polarization-sensitive broadband photodetector using a black phosphorus vertical p–n junction. Nat. Nanotechnol. 10, 707–713 (2015).

    Google Scholar 

  36. 36.

    Xia, F., Wang, H. & Jia, Y. Rediscovering black phosphorus as an anisotropic layered material for optoelectronics and electronics. Nat. Commun. 5, 4458 (2014).

    Google Scholar 

  37. 37.

    Bullock, J. et al. Polarization-resolved black phosphorus/molybdenum disulfide mid-wave infrared photodiodes with high detectivity at room temperature. Nat. Photon. 12, 601–607 (2018).

    Google Scholar 

  38. 38.

    Lee, Y. T. et al. Nonvolatile charge injection memory based on black phosphorous 2D nanosheets for charge trapping and active channel layers. Adv. Funct. Mater. 26, 5701–5707 (2016).

    Google Scholar 

  39. 39.

    Kim, K. S. et al. Ultrasensitive MoS2 photodetector by serial nano-bridge multi-heterojunction. Nat. Commun. 10, 4701 (2019).

    Google Scholar 

  40. 40.

    Vu, Q. A. et al. Tuning carrier tunneling in van der Waals heterostructures for ultrahigh detectivity. Nano Lett. 17, 453–459 (2017).

    Google Scholar 

  41. 41.

    Kopytko, M. et al. Engineering the bandgap of unipolar HgCdTe-Based nBn infrared photodetectors. J. Electron. Mater. 44, 158–166 (2014).

    Google Scholar 

  42. 42.

    Itsuno, A. M., Phillips, J. D. & Velicu, S. Mid-wave infrared HgCdTe nBn photodetector. Appl. Phys. Lett. 100, 161102 (2012).

    Google Scholar 

  43. 43.

    Wu, D. H., Zhang, Y. Y. & Razeghi, M. Room temperature operation of InxGa1−xSb/InAs type-II quantum well infrared photodetectors grown by MOCVD. Appl. Phys. Lett. 112, 111103 (2018).

    Google Scholar 

  44. 44.

    Mehew, J. D. et al. Fast and highly sensitive ionic-polymer-gated WS2–graphene photodetectors. Adv. Mater. 29, 1700222 (2017).

    Google Scholar 

  45. 45.

    Saran, R. & Curry, R. J. Lead sulphide nanocrystal photodetector technologies. Nat. Photon. 10, 81–92 (2016).

    Google Scholar 

Download references


W.H. acknowledges support from the National Natural Science Foundation of China (grant nos. 61725505, 11734016 and 61521005), National Key Research and Development Programme of China (grant no. 2020YFB2009300), Research Project of Frontier Science of CAS (grant no. QYZDB-SSW-JSC031) and Fund of Shanghai Natural Science Foundation (grant no. 19XD1404100). Yunfeng Chen and Z.W. acknowledge support from the Fund of SITP Innovation Foundation (grant nos. CX-235 and 348).

Author information




W.H. and P.Z. conceived the idea and designed the experiments. Yunfeng Chen and Y.W. carried out most of the experiments and analysed the data. P.W., P.Z., J.M., X.Chen, W.L. and Z.H. analysed the data. Y.G., R.X. and Q.L. contributed to the theoretical calculations. Y.Y. and F.W. performed Raman measurements. X.Chai and Y.Z. carried out Fourier transform infrared measurements. J.Y. and L.Z. conducted the atomic force microscopy measurements. Yan Chen and J.W. conducted the Kelvin probe force microscopy measurements. W.H. was responsible for project planning. Yunfeng Chen, Y.W., Z.W., P.Z. and W.H. co-wrote the manuscript. All authors discussed the results.

Corresponding authors

Correspondence to Peng Zhou or Weida Hu.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature Electronics thanks Jiansheng Jie and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Figs, 1–33, Tables 1 and 2 and notes 1 and 2.

Supplementary Data 1

Statistical supplementary data.

Source data

Source Data Fig. 2

Statistical source data.

Source Data Fig. 3

Statistical source data.

Source Data Fig. 4

Statistical source data.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Chen, Y., Wang, Y., Wang, Z. et al. Unipolar barrier photodetectors based on van der Waals heterostructures. Nat Electron 4, 357–363 (2021).

Download citation


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing