Conduction Band Offsets Research Articles

Band alignment of h-BN/β-Ga2O3 heterostructure grown via ion beam sputtering deposition

Integrating two-dimensional ultra-wide band gap hexagonal boron nitride (h-BN) on β-Ga2O3 surface into van der Waals heterostructures is of great interest for developing novel high-power devices and optoelectronic devices because of their unique properties. The energy band alignment at the heterointerface is critical for device design, however, the band alignment of h-BN/β-Ga2O3 heterojunction has not been investigated to date. In this work, the h-BN/β-Ga2O3 heterostructure is constructed by directly growing h-BN few-layer on the β-Ga2O3 single crystal substrate using ion beam sputtering deposition method. The high-quality few-layer h-BN with the abrupt interface and smooth surface allow for the accurate determination of band alignment at the h-BN/β-Ga2O3 heterointerface by X-ray photoelectron spectroscopies. The valence and conduction band offsets are determined to be 0.47 and 1.42 eV for the h-BN/β-Ga2O3 heterostructure, respectively, with a type-Ⅱ staggered band alignment. Furthermore, the electronic structures of h-BN/β-Ga2O3 heterostructure are also investigated experimentally and theoretically. These results indicate that the h-BN/β-Ga2O3 heterostructure has great potential in (opto)electronic devices.

Thin SnxNiyOz Films as p-Type Transparent Conducting Oxide and Their Application in Light-Emitting Diodes.

The development of good-quality p-type transparent conducting oxides (TCOs) is essential to realize the full potential of TCOs for transparent electronics. This study investigates various optical and electrical properties of SnxNiyOz under different deposition conditions to achieve high-performance p-type TCOs. We found that a film with 20% O2/Ar deposited at room temperature exhibits the highest p-type conductivity with a carrier concentration of 2.04 × 1017 cm-3, a resistivity of 14.01 Ωcm, and a Hall mobility of 7.7 cm2 V-1 S-1. We also studied the elemental properties of a SnxNiyOz film and the band alignment at the SnxNiyOz/InP interface and found reasonably large values of the conduction band offset (CBO) and valence band offset (VBO). Finally, we demonstrate stable light-emitting diodes (LEDs) with n-InP nanowires (NWs) conformably coated with a p-SnxNiyOz structure. Several films and devices were fabricated and tested over a span of 6 months, and we observed similar characteristics. This confirms the stability and reliability of the films as well as the reproducibility of the LEDs. We also investigated the temperature-dependent behavior of these LEDs and observed an additional peak due to a zinc blende/wurtzite (ZB/WZ) transition at the InP substrate and NW interface at ∼98 K and below. This study provides promising results of SnxNiyOz as a potential p-type TCO candidate for applications in electronics and optoelectronics.

Optical and interfacial characteristics of a heterojunction between (2¯01)-oriented single-domain β-(In0.072Ga0.928)2O3 and α-Al2O3 crystals

In this article, we determine the band alignment at the thermodynamically stable heterointerface between a ( 2 ¯ 01 )-oriented single-domain β-(In0.072Ga0.928)2O3 crystal and bulk c-plane sapphire, namely, (0001)-oriented α-Al2O3. The β-(In0.072Ga0.928)2O3 layer was deposited on the bulk sapphire crystal using pulsed laser deposition. The β-(In0.072Ga0.928)2O3 and α-Al2O3 valence and conduction band offsets (VBO and CBO, respectively) were found to be 0 ± 0.1 and 4.87 ± 0.1 eV, respectively. Accordingly, we identified a type-I α-Al2O3/β-(In0.072Ga0.928)2O3 heterojunction. X-ray diffraction measurements confirmed ( 2 ¯ 01 )-oriented single-domain β-(In0.072Ga0.928)2O3 high-quality films with in-plane rotations of every 120 ∘ , whereas Rutherford backscattering spectrometry was employed to verify the bulk composition. We employed high-resolution X-ray photoelectron spectroscopy to measure the core level binding energies of Al 2p and Ga 2p3/2 with respect to the valence band maxima of the β-(In0.072Ga0.928)2O3 and α-Al2O3 layers, respectively. Then, we measured the energy separation between the Al 2p and Ga 2p3/2 core levels at the interface of the heterojunction. β-(InGa)2O3 is a wide-bandgap semiconductor, while α-Al2O3 is a well-known dielectric. Together, they can be employed to fabricate reliable and efficient power electronic devices. We also combined high-resolution transmission electron microscopy, X-ray diffraction, and fast Fourier transform algorithms to characterize the dislocations at the interface.

Investigation on high quality ultra-wide band gap β-Ga2O3/AlN heterostructure grown by metal organic chemical vapor deposition

β-Ga2O3 films were grown on AlN templates by metal organic chemical vapor deposition (MOCVD), and the properties of the β-Ga2O3/AlN heterostructures were investigated in detail. The β-Ga2O3/AlN heterostructure with abrupt interface was observed by the high resolution transmission electron microscope with high angle annular dark field. The refactor of the atoms at the interface is discussed. Moreover, the band structure of the MOCVD β-Ga2O3/AlN heterostructures was investigated by x-ray photoelectron spectroscopy. The conduction band and valence band offsets of β-Ga2O3/AlN heterostructure were calculated to be −1.44 eV ± 0.05 eV and −0.14 eV ± 0.05 eV, respectively.

Tailored Band Structure of Cu(In,Ga)Se2 Thin-Film Heterojunction Solar Cells: Depth Profiling of Defects and the Work Function.

An efficient carrier transport is essential for enhancing the performance of thin-film solar cells, in particular Cu(In,Ga)Se2 (CIGS) solar cells, because of their great sensitivities to not only the interface but also the film bulk. Conventional methods to investigate the outcoming carriers and their transport properties measure the current and voltage either under illumination or dark conditions. However, the evaluation of current and voltage changes along the cross-section of the devices presents several limitations. To mitigate this shortcoming, we prepared gently etched devices and analyzed their properties using micro-Raman scattering spectroscopy, Kelvin probe force microscopy, and photoluminescence measurements. The atomic distributions and microstructures of the devices were investigated, and the defect densities in the device bulk were determined via admittance spectroscopy. The effects of Ga grading on the charge transport at the CIGS-CdS interface were categorized into various types of band offsets, which were directly confirmed by our experiments. The results indicated that reducing open-circuit voltage loss is crucial for obtaining a higher power conversion efficiency. Although the large Ga grading in the CIGS absorber induced higher defect levels, it effectuated a smaller open-circuit voltage loss because of carrier transport enhancement at the absorber-buffer interface, resulting from the optimized conduction band offsets.

Annealing temperature dependence of band alignment of NiO/β-Ga2O3

The band alignment of sputtered NiO on β-Ga2O3 was measured by x-ray photoelectron spectroscopy for post-deposition annealing temperatures up to 600 °C. The band alignment is type II, staggered gap in all cases, with the magnitude of the conduction and valence band offsets increasing monotonically with annealing temperature. For the as-deposited heterojunction, ΔE V = −0.9 eV and ΔE C = 0.2 eV, while after 600 °C annealing the corresponding values are ΔE V = −3.0 eV and ΔE C = 2.12 eV. The bandgap of the NiO was reduced from 3.90 eV as-deposited to 3.72 eV after 600 °C annealing, which accounts for most of the absolute change in ΔE V−ΔE C. Differences in thermal budget may be at least partially responsible for the large spread in band offsets reported in the literature for this heterojunction. Other reasons could include interfacial disorder and contamination. Differential charging, which could shift peaks by different amounts and could potentially be a large source of error, was not observed in our samples.

Study of Metal–Dielectric Interface for Improving Electrical Properties and Reliability of DRAM Capacitor

AbstractThe interface between a dielectric thin film and a metal electrode is studied to improve reliability as well as electrical properties of the metal–insulator–metal (MIM) capacitor in dynamic random‐access memory (DRAM) devices. The interfacial layers between a dielectric thin film and a metal electrode play important functional roles such as increasing the electrical barrier or preventing oxygen defects in high‐k dielectrics. By introducing an electrical barrier layer or a sacrificial layer at the metal–dielectric interface for engineering the electronic band, lattice, or dipole, various effects could be confirmed such as the conduction band offset (CBO), bandgap or mismatch modulation for controlling the dielectric loss depending on the AC frequency or leakage current of MIM capacitors. Upon the insertion of Al2O3 as an electrical barrier layer, CBO increased because of the band engineering. Further, upon the insertion of TiO2 as a sacrificial layer at the interface, CBO increased because of the dipole formation at the interface, attributed to the difference in electronegativity. Thus, a robust MIM capacitor for DRAM that maintains a low leakage current and has improved reliability which is realized using the proper combination of interfacial layers.

Additive MXene and dominant recombination channel in perovskite solar cells

Two-dimensional (2D) MXenes have emerged as attractive materials for application in perovskite solar cells (PSCs). Their unique properties arising from terminating functional groups to tune the work function (WF) of the layers in a PSC lead to a notable improvement in the photovoltaic efficiency. The ideality factor (nid) is used to infer the dominant recombination type in the PSCs. We study the effect of the added MXene in the bulk absorber and the electron transport layer (ETL), and at the interfaces on the ideality factor (nid), and then the obtained nid is used to infer the dominant recombination type in the PSCs. By using the concept of intensity-dependent quasi-Fermi level splitting (QFLS), conduction and valence band offsets, and drift–diffusion simulations, we show that the bulk recombination in the MXene-free cells dominates. Considering the obtained nid values, we explain that adding MXene just into the absorber layer leads to a suppressed bulk recombination compared with the case of MXene-free device. Meanwhile, devices with added MXene into the ETL and at the ETL/absorber interface show a notable reduced interface recombination. The study of the interfacial energy offsets and their correlation with the interface and bulk recombination currents reveals that in the cells with MXene, higher nid values are desirable and correlate with better cell performance.

Understanding the strategies to attain the best performance of all inorganic lead‐free perovskite solar cells: Theoretical insights

Within a decade of their existence, the potential of Perovskite solar cells (PSCs) has been recognized by the research community. To date, the highest power conversion efficiency (PCE) attained by PSCs has touched the 25.8% mark. However, most of the leading PSCs have incorporation of toxic lead (Pb), posing a barrier on the market acceptability of these cells. Inorganic lead-free PSCs are being explored extensively as clean and green energy sources. By bridging the performance gap and stability issues, the drawbacks of lead-free PSCs can be minimized. In this work, we have optimized CsSn0.5Ge0.5I3-based PSCs using various organic and inorganic transport layers. A comparative analysis of all the simulated cells in terms of capacitance-voltage (C-V) and conductance-voltage (G-V) characterization has been done. This work reveals the decisive role of charge transport layers (CTLs) in the determination of the built-in potential of the cell. The impact of absorber layer thickness (with different levels of defect densities), variation of thickness of electron transport layer (ETL), and hole transport layer (HTL) on the performance of PSCs is studied. The results of study on the effect of carrier concentration on the absorber layer, ETL, and HTL (using both organic and inorganic charge transport layers) on the performance of the cell is also conducted. This study explains the role of energy band level tuning required between CTLs and the absorber layer. The role of band offset at the interface of the CTL (ETL/HTL) and perovskite layer upon charge transportation and collection mechanisms are explained in detail. We have calculated and explained the optimum Valence Band Offset and Conduction Band Offset required for a PSC to exhibit the best possible performance. In addition, we have analyzed the role of contact formation and optimum barrier height (¢B) required between HTL and back contact to obtain efficient PSC using different back contacts. Upon using similar cell configuration and different back contacts (Ni, Au, and Ag), the optimized values of (VBO, ¢B) are (0.15 eV, −0.05 eV), (0.1 eV, −0.4 eV), and (−0.15 eV, −0.51 eV), respectively.

Interfacial properties of 2D WS2 on SiO2 substrate from X-ray photoelectron spectroscopy and first-principles calculations

Two-dimensional (2D) WS2 films were deposited on SiO2 wafers, and the related interfacial properties were investigated by high-resolution X-ray photoelectron spectroscopy (XPS) and first-principles calculations. Using the direct (indirect) method, the valence band offset (VBO) at monolayer WS2/SiO2 interface was found to be 3.97 eV (3.86 eV), and the conduction band offset (CBO) was 2.70 eV (2.81 eV). Furthermore, the VBO (CBO) at bulk WS2/SiO2 interface is found to be about 0.48 eV (0.33 eV) larger due to the inter-layer orbital coupling and splitting of valence and conduction band edges. Therefore, the WS2/SiO2 heterostructure has a Type I energy-band alignment. The band offsets obtained experimentally and theoretically are consistent except the narrower theoretical bandgap of SiO2. The theoretical calculations further reveal a binding energy of 75 meV per S atom and the totally separated partial density of states, indicating a weak interaction and negligible Fermi level pinning effect between WS2 monolayer and SiO2 surface. Our combined experimental and theoretical results provide proof of the sufficient VBOs and CBOs and weak interaction in 2D WS2/SiO2 heterostructures.

Design and numerical simulation of highly efficient mixed‐organic cation mixed‐metal cation perovskite solar cells

Mixed cation perovskite type materials have recently shown considerable potential in high-efficiency single- and multi-junction solar cell devices. However, the operating principles of multiple cation-based perovskite solar cells are currently poorly understood. Furthermore, the photovoltaic performances of mixed cations-based perovskites solar cells are investigated using device simulator program. Inorganic TiO2 and Cu2O were used as electron transport layer and hole transport layer, respectively, because of their better performance. The impact of thickness, doping concentration and density of defect is examined using on the device performance. In addition, the effect of band offsets on performance was also investigated through altering the electron affinity of interface layers. Our calculated results reveal that a 700 nm absorber thickness is appropriate for a good solar cell device. Furthermore, impressive cell efficiency findings were obtained by adjusting defect density (1015-1016 cm−3) of the mixed perovskite active layer. The optimum conduction and valence band offsets, respectively, were determined to be 0.1 to 0.4 eV and 0.1 to 0.1 eV, allowing for a good performance of mixed perovskite devices. As an alternative to typical halide perovskite solar cells, our findings can be utilized to design and construct efficient mixed cations perovskite solar cell devices.

Design and characterization of Ge/SeO2 heterojunctions as tunneling thin film transistors

Herein stacked layers of germanium and selenium oxide are employed to fabricate heterojunction devices that can perform as a multifunctional thin film transistors (TFT). The stacked layers of Ge and SeO2 are coated onto ultrasonically cleaned glass and Ag thin film substrates using thermal deposition technique under a vacuum pressure of 1.5×10−4 mbar. The stacked layers are structurally, morphologically, optically and electrically characterized. It is observed that while amorphous germanium films exhibit two energy band gaps of values of 3.56 and 0.78 eV, amorphous SeO2 show one band gap of 3.70 eV. The conduction and valence band offsets at the Ge/SeO2 interfaces are 2.24 eV and 0.68 eV, respectively. Optically, the coating of SeO2 onto Ge films enhanced the light absorbability of SeO2 by ~ 50 times (at 2.38 eV) and ~17 times (at 1.71 eV) in the visible and infrared ranges of light, respectively. Formation of Ge/SeO2 is associated with a redshift and blue shift in the values of the energy band gaps of SeO2 and Ge, respectively. In addition, the current-voltage characteristic curve analyses have shown that Ag/Ge/SeO2/Ag TFTs is of tunneling type showing an estimated peak to valley current ratios of 2.0. The TFT displayed additional functionalities presented by PMOS characteristics, microwave resonators, negative capacitance sources and multiband band stop filters. The features of the devices nominate them for use in microwave technology as band stop filters of notch frequencies of 1.10 and 1.53 GHz.

The same band alignment of two hybrid 2D/3D vertical heterojunctions formed by combining monolayer MoS2 with semi-polar (11–22) GaN and c-plane (0001) GaN

Traditional c-plane (0001) GaN based devices are subject to a strong polarization field at the hetero-interfaces which handicaps the performance of photoelectric devices. However, the semi-polar (11–22) GaN has great potential for reducing the polarization effects compared with c-plane (0001) GaN. Here, we have fabricated MoS2/(11–22) GaN heterojunction and determined the band alignment by X-ray photoelectron spectroscopy (XPS). For comparison, the band alignment of MoS2/(0001) GaN heterojunction has also been measured to explore the influence of GaN with different crystal orientations on the energy band of MoS2/GaN heterojunction. Surprisingly, the band alignments of the two MoS2/GaN heterojunctions are the same, which could be caused by the unsaturated and omnidirectional properties of van der Waals forces at the interface of MoS2 and GaN. The measurement result of the valence band offsets (VBOs) of the two MoS2/GaN heterojunctions is 1.54 ± 0.15 eV. And the conduction band offsets (CBOs) are determined to be 0.29 ± 0.15 eV, revealing type-II band alignments of the two heterojunctions. We have also confirmed the number of MoS2 layers on the MoS2/GaN heterojunctions by Raman spectroscopy and the orientations of the GaN substrates by X-ray diffraction. The determination of band alignments between two-dimensional (2D) MoS2 and three-dimensional (3D) semi-polar (11–22) GaN opens up a way for modeling and designing high performance photoelectric devices based on hybrid MoS2/semi-polar GaN heterojunctions.

Band alignment of orthorhombic Ga2O3 with GaN and AlN semiconductors

Ga2O3 semiconductors have attracted tremendous research interests because of their fascinating material properties for future-generation energy, electronic, and optoelectronic applications. In the present study, we have performed the epitaxial growth of tin-doped Ga2O3 on sapphire, GaN, and AlN templates by the pulsed laser deposition technique. The initial characterizations show a two-dimensional mode of single-crystalline orthorhombic Ga2O3 (κ-Ga2O3) growth on these substrates with smooth surface morphology. Integrating κ-Ga2O3 with nitride semiconductors is interesting since both these materials possess polarization, which could induce 2-dimensional carrier gas (2DCG) at the interface. X-ray photoelectron spectroscopy studies reveal that both κ-Ga2O3/GaN and κ-Ga2O3/AlN heterostructure form a type-I band structure where the conduction band offset (CBO) was calculated to be 1.38 eV and 1.04 eV, respectively. This unique band alignment with high CBO could lead to the development of efficient power devices.

The performance of Perovskite solar cells with silicon carbide as an interfacial layer

The current work involved the numerical simulation of investigating the impact of conduction band offset (CBO) on the perovskite solar cell parameters. The solar cell structure under investigation comprises the (Spiro OMe TAD), (CH3NH3PbI3), and (SnO2) as HTL, the absorber layer, and ETL with electron affinities (χ) of (-2.45, -3.9, and -3.75) eV respectively. The conduction band alignment was controlled by inserting an interfacial layer between the absorber and ETL. The inserting layer is a thin layer of 3C-SiC material. Before utilizing the interfacial layer, a parametric study was attained, which included the doping variation and thickness variation of each layer. According to the findings, the device performs best at a thickness of 200 nm, 400 nm, 300 nm for HTL, perovskite absorber layer, and ETL respectively, with a doping concentration of 1019 cm-3, 1014 cm-3, and 1019 cm-3 for the same layers. These parameters provide a Jsc, Voc, FF, and PCE of 26.1 mA.cm-2, 1.11 V, 83.23%, and 24.19% respectively. Utilizing 3C-SiC as an interfacial layer with thickness 100 nm and doping 1018 cm-3 improved the performance of the device. According to the electron affinity for the proposed structure (the absorber layer and ETL) with the interfacial layer produce spike-spike band alignment. The results showed that the spike-spike band structure with (1= 0.07) eV for absorber layer with 3C-SiC and (2=0.08) eV for 3C-SiC interfacial layer and SnO2 as ETL, produces a good improvement in the cell performance with an increase in PCE (from 24.19 % to 28.36 %).

Impact of piezo-phototronic effect on ZnMgO/Se heterojunction photovoltaic devices

This paper investigates the impact of piezo-phototronic effects on the power conversion efficiency of ZnMgO/Se heterojunction photovoltaic devices. Sputter-deposited ZnMgO thin film and photo-absorbing Se were employed as the n-type window layer and p-type layer, respectively, to form a photovoltaic device on a flexible polyethylene terephthalate film. The applied strain was varied, and the changes due to the applied strain were recorded. The open-circuit voltage (Voc) increased from 0.59 V to 0.75 V when the applied strain was increased from − 0.41–0.40% by varying the bending angle. It has been reported that piezoelectric polarization of ZnMgO can decrease conduction band offset (CBO) between the ZnMgO and Se layers.

High‐Performance GaN HEMTs with ION/IOFF ≈1010 and Gate Leakage Current <10−11 A mm−1 Using Ta2O5 Dielectric

Herein, Ta2O5 high‐k gate dielectric‐based GaN high electron‐mobility transistors (HEMTs) with a high I ON/I OFF ratio and low gate leakage current are demonstrated without any significant deterioration of the other performance parameters. Ta2O5 with an average surface roughness of 1.8 nm and a dielectric constant of ≈26 are grown by sputtering and annealing in O2. The bandgap, valence, and conduction band offsets with Al0.3Ga0.7 N are 4.85, 0.24, and 0.61 eV, respectively. The reverse gate leakage current at −7 V is observed to be 1.2 ×10−10 A mm−1 for 5 nm and <1.0×10−11 A mm−1 for 20 and 30 nm oxide thickness compared to 5.0 × 10−6 A mm−1 for the control sample. This current is among the lowest ever reported for GaN‐based oxide‐HEMTs without significantly sacrificing other performances. The I ON/I OFF ratio is 2 × 109, 7 × 109, and 1 10 for 5, 20, and 30 nm oxide thickness, respectively, as compared to 2 × 108 for the control sample. The interface–state–density is estimated to be 1.5 × 1013 cm−2 eV−1. I DS,sat is measured to be 710, 700, and 690 mA mm−1 for 5, 20, and 30 nm Ta2O5 thickness, respectively, compared to 725 mA mm−1 for the control sample. The presence of oxide does not change the other characteristics much.

Quaternary – alloyed capping for strain and band engineering in InAs sub – monolayer quantum dots

In the last few years, a considerable amount of attention has been given to the optimization of several capping layers (CLs) in InAs/GaAs sub – monolayer (SML) quantum dots (QDs) heterostructure for a sustainable room – temperature (RT) operation in 1.3–1.55 μm telecommunication range (O, C – bands). In particular, the quaternary – alloyed capping (Q – CL: Q – Sb: InxGa1−xAsySb1−y, Q – N: InxGa1−xAsyN1−y, and Q – SbN: GaAsxSbyN1−x−y) has been explored in this work to reach the above – stated photoluminescence (PL) emission wavelength and we compared it with the conventional InAs/InxGa1−xAs QDs using Nextnano software. This tool is based on 8 – band k.p model that solves the self – consistent Schrödinger – Poisson equations analytically to obtain the envelope functions of the eigen energy levels (both electrons and holes) and finally the absorption spectra. Although Q – CL help in preserving QD morphology by strain reduction, it also allowed us create deep carrier confinement potential near conduction and valence band offsets i.e. CBO (VBO) where there is a minimum carrier escape probability towards GaAs barriers (more thermal stability) thus fostering a prolonged PL emission wavelength at 300 K. By changing atomic constituent's composition in Q – CLs, the obtained ground – state (GS) band – to – band absorption energy are 1.31 (Q – Sb22%, 1.25 (Q – N1.8%), 1.37 μm (Q – SbN2.2%))). Such deep confinement aid in the dark current reduction and can promote for high temperature operation by improving the PL quantum yield by several orders of magnitude. The inherent material properties of CL composing the surfactant effect of Sb, larger bond strength of tensile – strained dil.N, and phase separation effects of Sb–N alloys are advantageous in this regard to corroborate further PL redshift.

Effect of Annealing Temperature on the Microstructure and Optical Properties of Lanthanum-Doped Hafnium Oxide

Lanthanum-doped HfO2 films were deposited on Si by sol–gel technology. The effects of annealing temperature on the optical properties, interface chemistry, and energy band structure of Lanthanum-doped HfO2 films have been investigated. The crystallinity and surface morphologies of the films are strongly dependent on the annealing temperature. X-ray diffraction (XRD) analysis showed a monoclinic phase, and there was a tendency to preferentially grow with increasing temperature. The calculated grain sizes ranged from 17.1 to 22.4 nm on average. It was also confirmed from Raman spectroscopy that increasing the annealing temperature can improve the crystallinity of the films. The surface of the film was smooth, and the film had good interfacial contact with the silicon substrate. The band gap increased from 5.53 to 5.91 eV with increasing annealing temperature. The calculated conduction band offset and valence band offset both exceeded 1 eV. In conclusion, smaller grain size, good crystallinity and interfacial contact can be obtained by adjusting the annealing temperature. Higher conduction band and valence band offsets can meet the minimum barrier height requirements of complementary metal oxide semiconductors (CMOS) and have potential applications.

Interface Modification Uncovers the Potential Application of SnO2/TiO2 Double Electron Transport Layer in Efficient Cadmium‐Free Sb2Se3 Devices

AbstractAn undesirable p–n heterojunction interface of Sb2Se3 absorber with Cd‐free electron transport layer (ETL) is one of the key problems hindering the efficiency improvement of Sb2Se3 solar cell. Herein, a promising SnO2/TiO2 ETL coupled with SbCl3 treatment is introduced to improve the performance of Sb2Se3 solar cell. The mechanism of SbCl3 treatment on the crystal orientation of Sb2Se3 thin film and the p–n heterojunction interface of Sb2Se3 solar cell is disclosed combined with different characterization methods. The carrier transport property for Sb2Se3 thin film is enhanced, and the conduction band offset (CBO) of TiO2/Sb2Se3 interface is reduced from 0.57 to 0.20 eV by forming Sb2O3 interlayer at TiO2/Sb2Se3 interface after SbCl3 treatment, by which the interface recombination and the open circuit voltage deficit of the device can be effectively decreased, and the interface bonding at TiO2/Sb2Se3 interface can be effectively improved. Ultimately, the Cd‐free Sb2Se3 solar cell with configuration of ITO/SnO2/TiO2/Sb2Se3/Au achieves an efficiency of 5.82%, which is the highest efficiency in vapor transport deposition (VTD)‐processed Cd‐free Sb2Se3 solar cell at present. This work is expected to fill in the blank of VTD‐processed Cd‐free Sb2Se3 solar cell and offers a valuable reference for future band alignment of Sb2Se3 solar cell.