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

Abstract

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.

A Semi‐Floating Memory with 535% Enhancement of Refresh Time by Local Field Modulation

“…Given that the 2D materials have many unique advantages in modulation of electrical characteristics by external conditions, [ 5–12 ] it is possible to reduce the charge leakage of the p–n junction using a certain external condition. [ 13–20 ] In ferroelectric materials, there exists the spontaneous polarization and the polarization state can be changed by an external electric field.…”

Black Phosphorus n-type doping by Cu: a microscopic surface investigation

“…Here, we observe a positive Q 0 > 0, thus a positive value of the contact potential, which indicates an n-type doping of the bP, in agreement with our DFT-calculations and literature. 28,33 To corroborate these results and determine experimentally the length scale of the electronic effect driven by copper, we performed line-spectroscopic measurements across copper islands, as shown in Figure 5. We measured in total five different copper islands, and we see line spectra showing consistent behavior.…”

“…21 A more promising strategy for few-layer flakes could be surface charge transfer doping, which has been implemented on several two-dimensional materials such as graphene 22,23 and transition metal dichalcogenides. 24,25 For bP, few studies report n-type doping by surface charge transfer, [26][27][28][29][30][31][32][33][34] mostly for the case of alkali metals. 27,31,32 Electrical transport measurements show n-type behavior when bP is doped by the deposition of copper.…”

“…27,31,32 Electrical transport measurements show n-type behavior when bP is doped by the deposition of copper. 28,33 However, no local spectroscopic investigation has been performed so far to understand the effect of Cu on the electronic properties of bP at the atomic level.…”

Novel two-dimensional monoelemental and ternary materials: growth, physics and application

“…Recently, a new cousin of graphene, called "plumbene," which has the famous Weaire-Phelan bubble structure, has been considered to bring a new boom in the post-Moore law period [11]. Since 2014, similar with Gr, composed of a single element with an atomic thickness profile, black phosphorus (BP), as a star monoelemental material with a tunable bandgap (0.3-2.0 eV) [12], low grain boundary and high carrier mobility (10 3 cm 2 · V −1 · s −1 ) [13], has been applied in anisotropic lithium and sodium intercalation [14], (opto) electronic devices [15][16][17], sensors, medical treatment and energy [18]. However, excellent BP devices have to be covered or sandwiched by hexagonal-nitrile boron (h-BN) due to their poor air stability [19].…”