Direct Band Gap Semiconductor Research Articles

The adjustable electronic and photoelectric properties of the WS2/WSe2 and WSe2/WTe2 van der Waals heterostructures

The two-dimensional (2D) transition metal dichalcogenides (TMDs) have interesting physical properties and potential applications in the field of electronics and nanophotonics. The structure, electronic, optical and photoelectric properties of WX2 (X = S, Se, Te) monolayer and their heterostructures are studied by the first principles calculation. The results show that the six different stacked structures of the WS2/WSe2 and WSe2/WTe2 heterostructures have very small and negligible effects on their electronic properties. The electronic properties of the WS2/WSe2 and WSe2/WTe2 heterostructures can be effectively regulated by biaxial strain, such as the transition from the direct bandgap semiconductor to the indirect band gap and then to the metallic property. The WS2/WSe2 and WSe2/WTe2 heterostructures are type-II band alignments, which are suitable for optoelectronic applications. Moreover, both tensile strain and compressive strain can effectively regulate the optical properties of WS2/WSe2 heterostructure, such as the peak and range of optical absorption coefficient. These good optical properties are conducive to the application of the WS2/WSe2 heterostructures in optoelectronic devices. Therefore, the photoelectric characteristics of three kinds of photoelectric devices for zigzag and armchair types (Z-type and A-type) based on the WS2/WSe2 heterostructures are studied, named PIN-junction, PIP-junction and NIN-junction photoelectric devices. The WS2/WSe2 heterostructure shows high anisotropy in the optoelectronic properties in the Z-type and A-type directions. The photoelectric properties of the A-type WS2/WSe2 heterostructure are better than those of the Z-type. The A-type WS2/WSe2 heterostructure has a higher photocurrent density under the AM1.5 standard. Our results suggest that the WS2/WSe2 and WSe2/WTe2 heterostructures are possible to make photodetector, and the strain can regulate the electronic and optical properties of the heterostructures, which have potential applications in photoelectric and other fields.

First-principles prediction of two-dimensional Janus XMInZ[formula omitted](X [formula omitted] Cl, Br, I; M [formula omitted] Mg, Ca; and Z [formula omitted] S, Se, and Te) with promising spintronic and photocatalytic properties

Janus two-dimensional (2D) materials with asymmetric structures and intrinsic dipole moments have recently drawn enormous attention due to their appealing performance in diverse fields of nanoelectronics, optoelectronics, spintronics, and photocatalytic water splitting. In this paper, we propose a novel 2D Janus family named XMInZ2(X = Cl, Br, I; M = Mg, Ca; and Z = S, Se, and Te) and investigate their properties employing first-principles calculations. Using phonon dispersion, seventeen compounds of the predicted XMInZ2 monolayers are proved to be dynamically stable. The electronic band structures reveal that all stable XMInZ2 monolayers are direct bandgap semiconductors among which XMgInZ2 have larger bandgaps than XCaInZ2 monolayers. Lack of mirror symmetry gives rise to distinct Rashba spin-splitting (RSS) at Γ point of conduction bands in most XMInZ2 monolayers and the largest Rashba coefficient (αRΓC= 1.112 eVÅ) belongs to BrCaInTe2. Furthermore, comparing the projected band structures with and without the spin–orbit coupling (SOC) effect, it is found that the inclusion of SOC leads to band inversion between the lower conduction band (LCB) and upper valence band (UVB) of ICaInS2 monolayer. In terms of photocatalytic properties, some Janus XMInZ2 monolayers possess appropriate band edge positions for overall water splitting owing to their intrinsic dipole moments. Particularly, BrMgInTe2, BrCaInTe2, and ICaInTe2 due to their smaller bandgaps, larger solar light absorptions, and efficient separation and transport of electrons and holes are superior photocatalysts for water splitting. These explorations can pave the way for the design of highly efficient spintronic and photocatalytic devices.

Polarization and built-in electric field improve the photocatalytic overall water splitting efficiency of C2N/ZnSe heterostructures

The type-II van der Waals heterostructure photocatalytic system is an ideal band alignment structure for photocatalysis, which the high separation efficiency of photo-induced carriers. By using density functional theory, we predicted two van der Waals (vdW) heterostructures, namely, C2N/ZnSe-ML (monolayer) and C2N/ZnSe-BL (bilayer), respectively. For the C2N/ZnSe-BL heterostructure, it has an intrinsic type-II band alignment, in which the built-in electric field formed at the interface accelerates the separation of photogenerated electrons-holes in heterostructure. The photogenerated electrons-holes have been accumulated near the conduction band minimum of C2N and the valence band maximum of ZnSe-BL, respectively, which the C2N/ZnSe-BL heterostructure is a type-II photocatalytic heterostructure. However, the C2N/ZnSe-ML heterostructure has a strong built-in electric field from C2N to ZnSe-ML because the ZnSe-ML is a polarized material with a polarized electric field inside, which form a type-Ⅱ heterostructure and realizes the effective separation of photogenerated electron-holes under the action of built-in electric field. The C2N/ZnSe-X (ML, BL) heterostructures are both direct band-gap semiconductors and they can harvest sunlight efficiently almost in the range of the solar spectrum. These distinguishing features confirm that the C2N/ZnSe-X (ML, BL) heterostructures have promising prospects in the sphere of photocatalysis for the separation of photogenerated electron-holes.

First-principles study of electronic and optical properties of NH3-adsorbed Sc2CO2 monolayer and its application in gas sensors

Two-dimensional Sc2CO2 MXene materials have been considered highly potential for gas capture and gas sensor applications. In this study, the adsorption behaviors of small molecules such as NH3, SO3, O2, H2CO and C2H4 on Sc2CO2 monolayer were investigated using first-principles methods. Our results demonstrate the preferential adsorption of NH3 over other species with adsorption energies as high as −0.55 eV. And Sc2CO2 is transformed from an indirect bandgap semiconductor to a direct bandgap semiconductor after NH3 adsorption, and the appropriate band gap makes it potential for light absorption and photodetection. In addition, the carrier mobility of Sc2CO2 monolayer is significantly enhanced by adsorption, making it easy to detect changes in resistance. The room-temperature electron mobilities of NH3-adsorbed Sc2CO2 along armchair and zigzag directions are predicted to be as high as 16.75 × 103 and 13.19 × 103 cm2V−1S−1, while the room-temperature hole mobilities along armchair and zigzag directions are determined to be 10.77 × 103 and 11.09 × 103 cm2V−1S−1, respectively. According to the present results, Sc2CO2 monolayer is expected to be promising for the design and application of efficient NH3 gas sensor devices with high selectivity, high sensitivity and low recovery time through analytical methods based on optical and/or electronic responses.

A 2D Bismuth-Induced Honeycomb Surface Structure on GaAs(111).

Two-dimensional (2D) topological insulators have fascinating physical properties which are promising for applications within spintronics. In order to realize spintronic devices working at room temperature, materials with a large nontrivial gap are needed. Bismuthene, a 2D layer of Bi atoms in a honeycomb structure, has recently attracted strong attention because of its record-large nontrivial gap, which is due to the strong spin-orbit coupling of Bi and the unusually strong interaction of the Bi atoms with the surface atoms of the substrate underneath. It would be a significant step forward to be able to form 2D materials with properties such as bismuthene on semiconductors such as GaAs, which has a band gap size relevant for electronics and a direct band gap for optical applications. Here, we present the successful formation of a 2D Bi honeycomb structure on GaAs, which fulfills these conditions. Bi atoms have been incorporated into a clean GaAs(111) surface, with As termination, based on Bi deposition under optimized growth conditions. Low-temperature scanning tunneling microscopy and spectroscopy (LT-STM/S) demonstrates a well-ordered large-scale honeycomb structure, consisting of Bi atoms in a √3 × √3 30° reconstruction on GaAs(111). X-ray photoelectron spectroscopy shows that the Bi atoms of the honeycomb structure only bond to the underlying As atoms. This is supported by calculations based on density functional theory that confirm the honeycomb structure with a large Bi-As binding energy and predict Bi-induced electronic bands within the GaAs band gap that open up a gap of nontrivial topological nature. STS results support the existence of Bi-induced states within the GaAs band gap. The GaAs:Bi honeycomb layer found here has a similar structure as previously published bismuthene on SiC or on Ag, though with a significantly larger lattice constant and only weak Bi-Bi bonding. It can therefore be considered as an extreme case of bismuthene, which is fundamentally interesting. Furthermore, it has the same exciting electronic properties, opening a large nontrivial gap, which is the requirement for room-temperature spintronic applications, and it is directly integrated in GaAs, a direct band gap semiconductor with a large range of (opto)electronic devices.

Tuning inter‐wall spacing and structural properties of double‐walled gallium arsenide nanotubes

AbstractThe structural, stability and electronic properties of double‐walled GaAs nanotubes (DWGaAsNTs) are investigated based on density functional theory (DFT) by considering Van der Waals corrections with the SIESTA code. The computations are done on the zigzag (7,0)@(m,0) and (6,0)@(m,0) with (m = 12 to 18) and the armchair (4,4)@(m,m) and (5,5)@(m,m) DWGaAsNTs with (m = 7 to 14). The calculated binding and formation energies revealed that the armchair and zigzag DWGaAsNTs with differential chirality of 5, (m,m)@(m + 5,m + 5) and 8, (m,0)@(m + 8,0) and inter‐layer space of roughly 5.4 and 4.9 Å are the most favorable DWGaAsNTs, respectively. All armchair and zigzag DWGaAsNTs are direct bandgap semiconductors according to the electronic band structure. Furthermore, it is found that with increasing the spaces between walls and diameters of the tubes, the value of the band gap increases, and the changing trend is almost constant at greater distances between walls. Also, the double‐walled GaAs nanotubes have a narrower bandgap than single‐walled nanotubes. The implications of this research can certainly be useful in future empirical studies.

First-principles calculations to investigate electronic structure and optical spectra of CdxZn1-xS ternary semiconductor alloys

The structural parameters, electronic band structure and optical spectra of CdxZn1-xS (0 ≤ x ≤ 1) ternary semiconductor alloys are studied. The calculations are realized using the full potential linearized augmented plane wave method. The modified local density approximation (LDA) and generalized gradient approximation (GGA) have been used for describing the exchange-correlation potential. The obtained results for zinc-blende CdxZn1-xS ternary alloys show a general wellness with the data shown in the literature. An inspection of electronic band structure indicates that zinc-blende CdxZn1-xS are (Г→Г) direct band gap semiconductors (from x = 0 up to x = 1). A predominant ionic type of the chemical bonding in these materials has been indicated. The density of states shows various peaks in both valence and conduction localities proposing that an abundance of conditions is obtainable for occupation. The alloys affect the optical features of interest. The results obtained from the present work show that the zinc-blende CdxZn1-xS is a promettant material for photovoltaic device applications. Moreover, the alloy of interest can be used in different devices from visible to ultraviolet light.

Optical and dielectric response of two-dimensional WX2 (X = Cl, O, S, Se, Te) monolayers: A comprehensive study based on density functional theory.

Here, we study the dielectric and optical properties of two-dimensional (2D) WX2 monolayers, where X is Cl, O, S, Se, and Te. First principle electronic band structure calculations reveal that all materials are direct band gap semiconductors except WO2 and WCl2 , which are found to be indirect band gap semiconducting 2D materials. The dielectric response of these materials is also systematically investigated. The obtained results suggest that these materials are suitable as dielectric materials to suppress unwanted signal noise. The optical properties of these 2D materials, such as absorption, reflection and extinction coefficients, refractive index, and optical conductivity, are also calculated from the dielectric function. It is found that these materials exhibit excellent optical response. The present electronic, dielectric, and optical findings indicate that WX2 monolayers have an opportunity in electronic, optical, and optoelectronic device applications.

Strain and interfacial defect tailored electronic structures of two-dimensional WSe2/h-BN van der Waals heterostructure

In this work, strain and interfacial defect tailored electronic structures of h-BN/WSe2 heterostructure are investigated systematically. The results show that the WSe2/h-BN heterostructure is a direct bandgap semiconductor (1.211[Formula: see text]eV) with type-I band alignment compared with the isolated h-BN and WSe2 monolayers. Applying the in-plane strain can well adjust the electronic structure of heterostructure, resulting in a transition from indirect to direct bandgap at the strain of −2% for the h-BN/WSe2 heterostructures. The bandgap of h-BN/WSe2 heterostructure monotonically increases at the compressive strains from −6% to −2%, whereas decreases at the tensile strains from 0% to 8%. In addition, introducing of vacancy defects and n- or p-type doping can effectively alter the band alignment of heterostructure. When the N and B vacancies or C doping are introduced in the h-BN layer, a significant transform from type-I to type-II band alignment is observed. These results suggest the h-BN/WSe2 heterostructure becomes a good candidate for the application of optoelectronics and nanoelectronics devices.

Multi-functional lead-free Ba2XSbO6 (X = Al, Ga) double perovskites with direct bandgaps for photocatalytic and thermoelectric applications: A first principles study

In this paper, the structural formability, electronic, optical, and thermoelectric properties of Ba2XSbO6 (X = Al, Ga) double perovskite oxides are investigated with density functional theory (DFT). Based on our calculations, by considering dynamic stability, energetic stability, the (τ)-tolerance and the (μ)-octahedral factors, both Ba2AlSbO6 and Ba2GaSbO6 double perovskites show perfectly cubic structures with space group Fm-3 m (space group no: 225). Our calculations revealed that Ba2AlSbO6 and Ba2GaSbO6 are semiconductors with direct bandgaps of about 2.87 and 1.86 eV. As a direct bandgap semiconductor with tunable electronic and optical properties, it has been found that these materials are promising candidates for use in water splitting. Furthermore, optical properties investigation has represented remarkable optical properties as they exhibit good absorption coefficients in the visible region of the spectrum. Moreover, we investigated the effect of hydrostatic pressure in the 0–8 GPa range on the compounds' electronic properties and discovered that stress increases the bandgap of the materials while their band gaps remain direct. Finally, our study on the thermoelectric characteristics of Ba2AlSbO6 and Ba2GaSbO6 indicates that they have good Seebeck coefficients and thermoelectric power factors, making them promising thermoelectric materials. The obtained tunable moderate bandgaps, good optical absorption in the visible light region, and high power factors suggest the double perovskite materials for use in different electronic, optical and thermoelectric applications, especially in new energy production applications.

Two-Dimensional Octuple-Atomic-Layer M2Si2N4 (M = Al, Ga and In) with Long Carrier Lifetime

Bulk III-nitride materials MN (M = Al, Ga and In) and their alloys have been widely used in high-power electronic and optoelectronic devices, but stable two-dimensional (2D) III-nitride materials, except h-BN, have not been realized yet. A new kind of 2D III-nitride material M2Si2N4 (M = Al, Ga and In) is predicted by choosing Si as the appropriate passivation element. The stability, electronic and optical properties of 2D M2Si2N4 materials are studied systematically based on first-principles calculations. The results show that Al2Si2N4 and Ga2Si2N4 are found to be indirect bandgap semiconductors, while In2Si2N4 is a direct bandgap semiconductor. Moreover, Al2Si2N4 and In2Si2N4 have good absorption ability in the visible light region, while Ga2Si2N4 is an ultraviolet-light-absorbing material. Furthermore, the carrier lifetimes of Ga2Si2N4 and In2Si2N4 are as large as 157.89 and 103.99 ns, respectively. All these desirable properties of M2Si2N4 materials make them attractive for applications in electronics and photoelectronics.

Structural, elastic, and electronic properties of BC12 carbon under pressure

The crystal structure, mechanical, elastic anisotropy in shear modulus, Young’s modulus and Poisson’s ratio, electronic band structures and X-ray diffraction (XRD) pattern of BC12 carbon are investigated by density functional theory. The elastic anisotropy calculations show that BC12 carbon has smaller anisotropy in Young's modulus, and shear modulus than that of Poisson's ratio. The elastic anisotropy in the shear modulus, Young's modulus, and Poisson's ratio is almost unchanged. The band structure calculations reveal that BC12 carbon is a direct band gap semiconductor material at ambient pressure, and it maintains the direct band gap semiconductor property up to 100 GPa. In addition, it is found that the diffraction angles of the same diffraction peak slightly increase with increasing pressure through the X-ray diffraction (XRD) pattern.

First-principles calculations of Mg2FeH6 under high pressures and hydrogen storage properties.

We report on structural properties, elastic constants, mechanical and dynamical stabilities, electronic band structure, and hydrogen storage applications of Mg2FeH6 at zero and high-pressure effects. The work has been realized within the full-potential linearized augmented plane wave method. At zero pressure, the material under study is stable and has a ductile nature. The electronic structure of the material of interest is determined to be X-X wide direct band gap semiconductor with an energy of 1.88eV. The hydrogen storage capacity wt (%) and the hydrogen desorption temperature are reported as 5.473 and 625.47K respectively. The Debye temperature ϴD is recorded as 698K using the elastic constants and about 775K using the Gibbs calculations. Under high-pressure effect up to 80GPa, the semiconductor still be an X-X semiconductor with an energy gap of 3.91eV. The Debye temperature ϴD increases monotonically up to about 1120K at 80GPa when using the calculated elastic constants whereas the desorption temperature decreases from 650 to 0K by increasing pressure from 0 to about 87GPa.

First-principles calculations to investigate structural and mechanical properties of MoS2/MoSe2 vertical and lateral Superlattice

MoS2/MoSe2 superlattice is a potential candidate for thermoelectric materials. We have theoretically constructed MoS2/MoSe2 vertical and lateral superlattices based on the density functional theory. Here, five possible stacking structures of MoS2/MoSe2 vertical superlattice are considered. The optimized energy of AA1 structure is the lowest. The structural stability, electronic and mechanical properties of AA1 structure and lateral superlattice (LS) are studied. The results shows that AA1 and LS are thermodynamically, dynamically and mechanically stable. The calculated band structures display AA1 is an indirect bandgap semiconductor, while LS is a direct bandgap semiconductor. Furthermore, the sound speed of LS is slightly lower than that of AA1. The sound velocity of LS has a little anisotropy and is minimum in the [01] direction.

Electronic, mechanical, and optical properties of BP nanotubes: A first-principles study

The electronic, mechanical, and optical properties of (3,3), (5,5), (7,7) and (9,9) armchair and (4,0), (6,0), (8,0), (10,0) and (12,0) zigzag boron phosphide nanotubes (BPNT’s) have been investigated using density functional theory calculations. We find that, with the exception of the (5,5) nanotube, they are direct band gap semiconductors, as the BP monolayer. The (3,3) and (4,0) nanotubes are verified to be unstable through phonon band structure calculations. The 1D stretching moduli and elastic moduli show that the BP NT’s are as stiff as carbon nanotubes of comparable diameters. The absorption spectra of the BP nanotubes have thresholds in the visible region, differently from carbon and boron nitride nanotubes of comparable dimensions.

Cmc21-CdO: Emerging direct band gap semiconductor with ultrahigh mobility and enhanced visible-light optical absorptions

In this paper, an unreported polymorph of cadmium oxide with a direct band gap (denoted as Cmc21-CdO) is proposed based on the adaptive genetic algorithm (AGA) crystal structure prediction method. The mechanical, dynamical, and thermodynamic stability are all present in the Cmc21-CdO phase. The Cmc21-CdO is more anisotropic and ductile than ground state B1–CdO according to the anisotropic factor and elastic moduli (B, G, and E), respectively. The calculated optical characteristics show that Cmc21-CdO exhibits higher optical absorption and lower reflectivity versus B1–CdO in visible light, and is more suitable for solar cell applications. Meanwhile, Cmc21-CdO phase has an ultrahigh electron-dominated mobility (7.602 × 104 cm2V−1s−1), which is much larger than B1 phase (0.350 × 104 cm2 V−1 s−1). More interestingly, we discover that Cmc21-CdO will undergo a phase transition in response to compressive stress, whereas under tensile stress, its optical spectrum will be redshifted and its band gaps will decrease.

2D Janus MoSSe/MoGeSiN4 vdW heterostructures for photovoltaic and photocatalysis applications

Photoelectric catalytic and solar cells are two effective ways to solve the global energy shortage and environmental pollution problems. However, low carrier separation efficiency has been becoming a common problem of current photocatalytic water decomposition and solar cells. In this work, both the electronic structures and optical properties of Janus MoSSe/MoGeSiN4 vdW heterostructures were systematically studied by density functional theory. The results show that the Janus MoSSe/MoGeSiN4 vdW heterostructure with Se/Ge interfacial contact (Se/Ge heterostructure) is a direct band gap semiconductor. Interestingly, for the Se/Ge heterostructure, spatial separation of the photo-generated electrons and holes is expected, due to the conduction band minimum (CBM) and the valence band maximum (VBM) separately locating on the MoGeSiN4 and MoSSe layer. Besides, the Se/Ge heterostructure not only exhibits considerable absorption index in the visible light range but also maximum theoretical photoelectric conversion efficiency approaches 26.4 %, which can be furthermore enhanced by varying the layer distance and biaxial strain. The Se/Ge heterostructure shows high carrier mobility, obvious carrier separation, notably visible light absorption and tunable photoelectric properties, making it promising candidates for novel two dimensional photocatalysis devices and solar cells.

A theoretical study of novel orthorhombic group-IVB nitride halide monolayers for photocatalytic overall water splitting.

Hydrogen energy is very important as a new clean energy source to combat the growing environmental problems. In this regard, novel photocatalyst materials for water splitting have a wide range of applications. Using first principles calculations, we theoretically studied three orthorhombic group-IVB nitride halide monolayers, Hf2N2Br2, Janus HfZrN2Br2 and Janus Hf2N2ClBr. The energy, dynamic and thermal stabilities are demonstrated for all three monolayers. Using the HSE hybrid functional, the calculations reveal that they are direct band gap semiconductors with suitable band edge positions, good optical absorptions, and anisotropic carrier mobilities, which makes them promising for water splitting applications. Importantly, the photogenerated carriers provide enough driving force to trigger the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) within wide pH ranges, and then overall water splitting can be achieved spontaneously. We conclude that orthorhombic group-IVB nitride halide monolayers have potential applications in photocatalytic nanodevices.

Theoretical prediction of valley spin splitting in two-dimensional Janus MSiGeZ4 (M = Cr and W; Z = N, P, and As).

With the exploration of valleytronic materials in MA2Z4 structures, larger valley spin splitting has become a hot topic of research. Based on first-principles calculations, we predicted six valleytronic 2D (two-dimensional) Janus MSiGeZ4 (M = Cr and W; Z = N, P, and As) materials. The valley spin splitting value of WSiGeZ4 (Z = N, P, and As) can reach more than 400 meV, which is favorable for the practical application of valleytronics. Two-dimensional WSiGeZ4 (Z = N, P, and As) materials are dynamically and mechanically stable and have an abundance of electronic properties. The two-dimensional Janus WSiGeZ4 (Z = N, P, and As) structures comprise both direct and indirect bandgap semiconductor materials. Among them, WSiGeN4 is an indirect bandgap semiconductor material with a bandgap of 1.654 eV and WSiGeP4 is a direct bandgap semiconductor material. The valley spin splitting originates from the symmetry breaking of the material structure and the spin-orbit coupling effect of the transition metal, which is manifested as the Berry curvature. In particular, the Berry curvature of 2D Janus WSiGeP4 and WSiGeAs4 is as high as 300 Bohr2, which is quite large. The W atom has more d-orbital electrons than the Cr atom, and the SOC (spin-orbit coupling) effect is stronger; thus, the valley spin splitting value CrSiGeZ4 of WSiGeZ4 is more than 300 meV, which is quite large. In addition, the bandgap and valley spin splitting of WSiGeZ4 (Z = N, P, and As) can be significantly modulated by applying a biaxial strain. Our study shows that WSiGeZ4 (Z = N, P, and As) has great potential for valleytronic applications.

First-principles study of surface modification of CuSe

Original bulk phases of two-dimensional atomic crystal materials are layered. However, a few relevant researches show that some of two-dimensional material crystals have non-layered bulk phases. In this work we investigate monolayer CuSe which is non-layered, belonging in a new kind of honeycomb graphene analogue. Monolayer CuSe is not suitable for application in electronic devices because of its metallic nature. In order to find new two-dimensional atomic crystal materials with excellent performance suitable for application in electronic devices, we change CuSe from metal to semiconductor through external atom modification. The first principles study of density functional theory is conducted to ascertain the energy band structure of monolayer CuSe after second periodic atoms have been added to the top, center and bridge sites. The characteristics of monolayer CuSe with addition of Li or B atoms are studied, including energy band structure, the density of states, differential charge density, and crystal orbital Hamiltonian population. The results show that after adding Li atoms to CuSe, the CuSe transforms from metallic to semiconductive property at all three positions, and Li atom is more easily to be modified in the hexagonal center of CuSe, with band gap being about 1.77 eV, the Fermi level biased towards the top of the valence band. The CuSe with addition of Li atoms exhibits a p-type semiconductor property, so it is a direct bandgap semiconductor. Adding B atom to the top of Cu atom can also make CuSe semiconductive, with a band gap of about 1.2 eV, the conduction band minimum at the <i>K</i> point, and the valence band maximum at the <i>Γ</i> point. The CuSe with addition of B atoms belongs in an indirect band gap semiconductor, and the Fermi energy level is biased towards the conduction band minimum, exhibiting the characteristics of an n-type semiconductor. According to the results of differential charge density and crystal orbital Hamiltonian population, the B atom is bound to the top of the monolayer CuSe with the B-Se polar covalent bond. The first principle study reveals the realization of metal-to-semiconductor transition from monolayer CuSe to Cu<i>X</i>Se (<i>X</i> = Li, B), and the calculation results also show that CuSe with addition of Li atoms or B atoms is likely to be used in future electronic devices.