Khang D. Pham

Layered graphene/GaS van der Waals heterostructure: Controlling the electronic properties and Schottky barrier by vertical strain

In this work, we construct an ultrathin graphene/GaS heterostructure and investigate its electronic properties as well as the effect of vertical strain using density functional theory. The calculated results of the equilibrium interlayer spacing (3.356 A) and the binding energy show that the intrinsic properties of isolated graphene and GaS monolayers can be preserved and the weak van der Waals interactions are dominated in the heterostructures. The van der Waals heterostructure (vdWH) forms an n-type Schottky contact with a small Schottky barrier height of 0.51 eV. This small Schottky barrier height can also be tuned by applying vertical strain. Furthermore, we find that the n-type Schottky contact of the vdWH can be changed to p-type when the interlayer spacing is decreased and exceeded to 2.60 A. These findings show the great potential application of the graphene/GaS vdWH for designing next generation devices.In this work, we construct an ultrathin graphene/GaS heterostructure and investigate its electronic properties as well as the effect of vertical strain using density functional theory. The calculated results of the equilibrium interlayer spacing (3.356 A) and the binding energy show that the intrinsic properties of isolated graphene and GaS monolayers can be preserved and the weak van der Waals interactions are dominated in the heterostructures. The van der Waals heterostructure (vdWH) forms an n-type Schottky contact with a small Schottky barrier height of 0.51 eV. This small Schottky barrier height can also be tuned by applying vertical strain. Furthermore, we find that the n-type Schottky contact of the vdWH can be changed to p-type when the interlayer spacing is decreased and exceeded to 2.60 A. These findings show the great potential application of the graphene/GaS vdWH for designing next generation devices.

Electronic properties of GaSe/MoS2 and GaS/MoSe2 heterojunctions from first principles calculations

In this work, we theoretically investigate electronic properties of GaSeMoS2 and GaSMoSe2 heterojunctions using density functional theory based on first-principles calculations. The results show that both GaSeMoS2 and GaSMoSe2 heterojunctions are characterized by the weak vdW interactions with a corresponding interlayer distance of 3.45 A and 3.54 A, and the binding energy of −0.16 eV per GaSeGaS cell. Furthermore, one can observe that both the GaSeMoS2, and GaSMoSe2 heterojunctions are found to be indirect band gap semiconductors with a corresponding band gap of 1.91 eV and 1.23 eV, respectively. We also find that the band gaps of these semiconductors belong to type II band alignment. A type–II band alignment in both GaSeMoS2 and GaSMoSe2 heterojunctions open their potential applications as novel materials such as in designing and fabricating new generation of photovoltaic and optoelectronic devices.In this work, we theoretically investigate electronic properties of GaSeMoS2 and GaSMoSe2 heterojunctions using density functional theory based on first-principles calculations. The results show that both GaSeMoS2 and GaSMoSe2 heterojunctions are characterized by the weak vdW interactions with a corresponding interlayer distance of 3.45 A and 3.54 A, and the binding energy of −0.16 eV per GaSeGaS cell. Furthermore, one can observe that both the GaSeMoS2, and GaSMoSe2 heterojunctions are found to be indirect band gap semiconductors with a corresponding band gap of 1.91 eV and 1.23 eV, respectively. We also find that the band gaps of these semiconductors belong to type II band alignment. A type–II band alignment in both GaSeMoS2 and GaSMoSe2 heterojunctions open their potential applications as novel materials such as in designing and fabricating new generation of photovoltaic and optoelectronic devices.