Intricate modulation of interlayer coupling at the graphene oxide/$\mathrm{MoS}{\mathrm{e}}_2$ interface: Application in time-dependent optics and device transport

In the $\mathrm{GO}/\mathrm{MoS}{\mathrm{e}}_2$ semiconductor heterostructure, we have demonstrated a subtle control on the doping dynamics by modulating interlayer coupling through the combination of strain-reducing relative rotation of the constituting layers and variation of ligand type and concentration. By first-principles calculations incorporating spin-orbit coupling, we have investigated the impact of variable interlayer coupling in introducing noncollinear magnetic behavior in the heterostructure. The outcome of varying carrier type and their respective concentrations are investigated by static as well as time-dependent density functional calculations, which indicate the presence of optical anisotropy and time-dependent optical phenomena such as exciton quenching and band-gap renormalization. The performance of such heterostructures as channel material in devices with top and edge metal contacts is analyzed. Our self-consistent quantum transport calculations have evinced that the interface-induced variation in doping pattern is extrapolated only for devices with top contacts. The edge contact, although it exhibits a better transmission, is inefficient in sensing the ligand-induced doping modulation introduced via vertical interlayer charge transfer.

Figure 1

Structural geometry of $\mathrm{GO}/\mathrm{MoS}{\mathrm{e}}_2$ HS. (a) OH, (b) COOH, (c) Low, and (d) High.

Figure 2

(a) GGA-PBE band structure and (b) atom projected density of states (APDOS) of pure $\mathrm{MoS}{\mathrm{e}}_2$ structure. (c) Corresponding band structure and (d) $x$, $y$, $z$ spin components–projected DOS of $\mathrm{MoS}{\mathrm{e}}_2$ after incorporating SOC. For better visibility with respect to the total DOS, the components are magnified by an appropriate factor.

Figure 3

The atom projected fatbands for (a) G/$\mathrm{MoS}{\mathrm{e}}_2$ (HS1), (b) G-OH/$\mathrm{MoS}{\mathrm{e}}_2$ (HS2), and (c) G-Low/$\mathrm{MoS}{\mathrm{e}}_2$ (HS4). The fatband color code is labeled in the figure. The figures are normalized with respect to the calculated Fermi level of the respective systems.

Figure 4

Converged DFT+SOC charge density plots for (a) HS2, (b) HS3, (c) HS4, and (d) HS5. Overlapping between the constituent layers indicates the mutual charge transfer. Violet and green represent Mo and Se atoms, respectively, whereas brown represents carbon atoms. Oxygen atoms are denoted by red color.

Figure 5

Spin-density plots for HS2 for (a) $x$-, (b) $y$-, and (c) $z$-projected components; HS3 for (d) $x$, (e) $y$, and (f) $z$; HS4 for (g) $x$, (h) $y$, and (i) $z$; and HS5 for (j) $x$, (k) $y$, and (l) $z$.

Figure 6

The SO coupled $x$, $y$, and $z$ spin component–projected PDOS and corresponding absorption coefficients of $\mathrm{GO}/\mathrm{MoS}{\mathrm{e}}_2$ with different ligand concentration, (a) $\mathrm{MoS}{\mathrm{e}}_2$, (b) HS1, (c) HS2, (d) HS3, (e) HS4, and (f) HS5. Red, blue and green colors represents $x$, $y$, and $z$ directions, respectively. For better visibility with respect to the total DOS, the components are magnified by an appropriate factor.

Figure 7

The comparison of absorbance of different $\mathrm{GO}/\mathrm{MoS}{\mathrm{e}}_2$ HS with pristine $\mathrm{MoS}{\mathrm{e}}_2$ using different TDDFT mechanisms (BOS and LRC) and RPA calculations.

Figure 8

(a) A model device configuration having two electrodes, electrode extension, and a central region. (b) Model lateral contact and (c) model vertical contact.

Figure 9

The APDOS for the pristine system and different GO/$\mathrm{MoS}{\mathrm{e}}_2$ HS and the corresponding DOS for lateral and vertical interfaces with Au. For the first column, the energy scale is normalized by the difference of $E_{\mathrm{F}}$ of the corresponding system minus the $E_{\mathrm{F}}$ of the pristine $\mathrm{MoS}{\mathrm{e}}_2$ to make the $n$- and $p$-type shift evident.

Figure 10

Γ-point transmission of HS and pristine system at zero and 2 V bias for (a) lateral and (b) vertical contact. Comparison of I-V characteristics of HS and pure system with (c) lateral and (d) vertical contact configurations normalized by channel length. The spin-polarized I-V characteristic of HS and pure system with (e) lateral and (f) vertical contact configurations.

Figure 11

Interpolated contour plot of the transmission coefficients in reciprocal space at zero bias for pristine $\mathrm{MoS}{\mathrm{e}}_2$ (a) lateral and (b) vertical contact, for HS2 (c) lateral and (d) vertical contact, and for HS4 (e) lateral and (f) vertical contact. The center of the plot is the Γ point.