Contact‐Barrier Free, High Mobility, Dual‐Gated Junctionless Transistor Using Tellurium Nanowire

Abstract

The gate‐all‐around nanowire transistor, due to its extremely tight electrostatic control and vertical integration capability, is a highly promising candidate for sub‐5 nm technology nodes. In particular, the junctionless nanowire transistors are highly scalable with reduced variability due to avoidance of steep source/drain junction formation by ion implantation. Here a dual‐gated junctionless nanowire p‐type field effect transistor is demonstrated using tellurium nanowire as the channel. The dangling‐bond‐free surface due to the unique helical crystal structure of the nanowire, coupled with an integration of dangling‐bond‐free, high quality hBN gate dielectric, allows for a phonon‐limited field effect hole mobility of 570 cm2 V−1 s−1 at 270 K, which is well above state‐of‐the‐art strained Si hole mobility. By lowering the temperature, the mobility increases to 1390 cm2 V−1 s−1 and becomes primarily limited by Coulomb scattering. The combination of an electron affinity of ≈4 eV and a small bandgap of tellurium provides zero Schottky barrier height for hole injection at the metal‐contact interface, which is remarkable for reduction of contact resistance in a highly scaled transistor. Exploiting these properties, coupled with the dual‐gated operation, we achieve a high drive current of 216 μA μm−1 while maintaining an on‐off ratio in excess of 2 × 104. The findings have intriguing prospects for alternate channel material based next‐generation electronics.

Tellurium Single‐Crystal Arrays by Low‐Temperature Evaporation and Crystallization

“…Ni was used as the contact metal, as it can form near ohmic contact for holes due to the Fermi level pining near valence band for Te. [ 34,35 ] Te FETs exhibit a typical p ‐type characteristic due to the native defects (Figure 6c) with a common hysteresis behavior (Figure S17, Supporting Information). The transistor based on a single‐grain Te (≈6 nm) crystallized at 5 °C shows an effective hole mobility of 93 cm 2 V −1 s −1 , subthreshold swing of 2.7 V dec −1 and on/off current ratio of ≈10 5 (Figure 6c–e) at room temperature in vacuum environment (≈10 −5 mTorr).…”

Highly Efficient Full van der Waals 1D p‐Te/2D n‐Bi2O2Se Heterodiodes with Nanoscale Ultra‐Photosensitive Channels

“…In region III ( V gs > 15 V), the drain current merely begins to slightly decrease, since the Te channel cannot be effectively depleted due to its ultrahigh hole concentration originated from the narrow bandgap. [ 21 ] Notably, Figure 2h presents the current–voltage ( I – V ) curves of Te/Bi 2 O 2 Se heterojunction in linear (black) and logarithmic (red) scale with the source/drain bias range of −1 to 1 V with zero gate voltage in the dark. This device shows a strong rectification behavior, with a calculated ideality factor of 1.9 based on the diffusion theory of Shochley.…”

“…[ 38 ] According to the previous study, with rationally designed diameter/thickness, Te NWs combined with Bi 2 O 2 Se NSs in this work would produce a relatively high light absorption efficiency, which is suitable for photoelectronic applications. [ 21,27,39 ] Thus, we then carry out the Kelvin probe force microscopy (KPFM) measurement to reveal the Fermi level shift and determine the energy band alignment (Figure 4b). The contact potential difference (CPD) between the probe and the sample is calculated by $$\[ \begin{array}{*{20}{c}}{{V_{{\rm{CPD}}}} = \frac{{{W_{{\rm{Tip}}}} - {W_{{\rm{Sample}}}}}}{e}}\end{array} \]$$where W Tip and W Sample are the work function of the tip and the sample, respectively.…”

One-Dimensional Atomic Chains for Ultimate-Scaled Electronics

“…Interestingly, many inorganic 1D ACs are p-type semiconductors with good hole mobility. For example, a p-type GAA-NW FET was demonstrated using a Te NW as the semiconducting channel and BN as the insulating dielectric . With reasonable electrostatic control, a field-effect hole mobility of 1390 cm 2 V –1 s –1 was obtained, which surpasses the state-of-the-art hole mobility of strained Si.…”