Steep Slope p-type 2D WSe&lt;inf&gt;2&lt;/inf&gt; Field-Effect Transistors with Van Der Waals Contact and Negative Capacitance

Guo

et al. 2019

InfoMat

Self Cite

Black phosphorus (BP) has been shown as a promising two‐dimensional (2D) material for electronic devices owing to its high carrier mobility. To realize complementary electronic circuits with 2D materials, it is important to fabricate both n‐type and p‐type transistors with the same channel material. By engineering the contact region with copper (Cu)‐doped BP, here we demonstrate an n‐type carrier transport in BP field‐effect transistors (FETs), which usually exhibit strongly p‐type characteristics. Cu metal atoms are found to severely penetrate into the BP flakes, which forms interstitial Cu (Cuint)‐doped edge contact and facilitates the electron transport in BP. Our BP FETs in back‐gated configuration exhibit n‐type dominant characteristics with a high electron mobility of ~ 138 cm2 V−1 s−1 at room temperature. The Schottky barrier height for electrons is relatively low because of the edge contact between Cuint‐doped BP and pristine BP channel. The contact doping of BP by highly mobile Cu atoms gives rise to n‐type transport property of BP FETs. Furthermore, we demonstrate a p‐n junction on the same BP flake with asymmetric contact. This strategy on contact engineering can be further extended to other 2D materials.

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Bp Fets With Cu Contactmentioning

confidence: 99%

Section: Cu Diffusion In Bpmentioning

confidence: 99%

See 3 more Smart Citations

Interstitial copper‐doped edge contact for n‐type carrier transport in black phosphorus

Lin

Guo

et al. 2019

InfoMat

Self Cite

Low‐Power Complementary Inverter with Negative Capacitance 2D Semiconductor Transistors

Guo

et al. 2020

Adv Funct Materials

A fundamental limit for the supply voltage of conventional field-effect transistors is the long high-energy tail of the Boltzmann distribution of the carrier population at the source junction, which requires a gate voltage at least 60 mV to change one decade of current. Here 2D semiconductors are adopted as channel materials and hafnium zirconium oxide (HZO) as negative capacitance (NC) gate stack to realize low-power complementary logic inverter. With HZO/Al 2 O 3 NC gate stack, the 2D semiconductor field-effect transistor (FET) shows an average subthreshold slope less than Boltzmann limit (as low as 18 mV dec −1) at room temperature for both forward and reverse gate voltage sweeps, which allows to reach the same ON-state current at a lower V dd without increasing the OFF-state current. The drain current can be modulated by 5 × 10 4 within 220 mV, still exhibiting average SS below 60 mV dec −1. By constructing van der Waals contact to improve the charge injection and control the carrier type, unipolar p-type WSe 2 FET with reduced hole Schottky barrier height is achieved. The complementary inverter with MoS 2 and WSe 2 NCFETs shows the power consumption of 68 pW.

Field‐Effect Chiral Anomaly Devices with Dirac Semimetal

Chen

Zhang

et al. 2021

Adv Funct Materials

Self Cite

Charge‐based field‐effect transistors (FETs) greatly suffer from unavoidable carrier scattering and heat dissipation. Analogous to valley degree of freedom in semiconductors, chiral anomaly current in Weyl/Dirac semimetals is theoretically predicted to be nearly nondissipative over long distances, but still lacks experimental ways to efficiently control its transport. Here, field‐effect chirality devices are demonstrated with Dirac semimetal PtSe2, in which its Fermi level is close to the Dirac point in the conduction band owing to intrinsic defects. The chiral anomaly is further corroborated by the planar Hall effect and nonlocal valley transport measurement, which can also be effectively modulated by external fields, showing robust nonlocal valley transport with micrometer diffusion length. Similar to charge‐based FETs, the chiral conductivity in PtSe2 devices can be modulated by electrostatic gating with an ON/OFF ratio of more than 103. Basic logic functions in the devices are also demonstrated with electric and magnetic fields as input signals.