Sun Rujun

Xidian University

Cd-alloying CZTSSe (sulfur about 1%) film was prepared by selenizing CZTS precursor with CdS on the top. The XRD and Raman spectra indicated that Cd alloyed into CZTSSe lattice and the calculated Cd/(Cd+Zn) ratio was 0.13. Some small grains with increased Sn/Cu ratio existed near back contact. Grain growth enhanced after Cd alloying, resulting in a...

Currently, Fe doping in the ~10^18 cm-3 range is the most widely-available method for producing semi-insulating single crystalline-Ga2O3 substrates. Red luminescence features have been reported from multiple types of Ga2O3 samples including Fe-doped-Ga2O3 , and attributed to Fe or N at O. Herein, however, we demonstrate that the high-intensity red...

Here we report on the degradation processes of Au/Ni/β-Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Schottky diodes under forward bias stress which is related to their on-state reliabi...

Here we report on defect properties of atomic layer deposition (ALD) grown SiO $_{\text{2}}$ / $\beta $ -Ga $_{\text{2}}$ O $_{\text{3}}$ MOS capacitors using capacitance–voltage ( $\textit{C}$ – $\textit{V}$ ), UV-assisted $\textit{C}$ – $\textit{V}$ , and deep-level transient spectroscopy (DLTS). We investigated the defect properties on...

Performing deep level transient spectroscopy (DLTS) on Schottky diodes, we investigated defect levels below the conduction band minima (Ec ) in Czochralski-grown unintentionally doped (UID) and vertical gradient freeze-grown Zr-doped beta-Ga2O3 crystals. In UID crystals with an electron concentration of 10 17 cmÀ3 , we observe levels at 0.18 eV and...

In this article, a novel device structure of an enhancement-mode (E-mode) Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> MOSFET is proposed based on the combination of the p-NiO/n-Ga <su...

In this work, we quantify electronic and ionic contributions to conductivity in the bulk and depletion widths of back-to-back sputtered Pt Schottky contacts on single crystals of β-Ga 2 O 3 . We also demonstrate asymmetric changes to these contacts induced by DC bias at temperatures as low as 200 °C, which has obvious bearing on the performance and...

High quality dielectric‐semiconductor interfaces are critical for reliable high‐performance transistors. This paper reports the in situ metal–organic chemical vapor deposition of Al2O3 on β‐Ga2O3 as a potentially better alternative to the most commonly used atomic layer deposition (ALD). The growth of Al2O3 is performed in the same reactor as Ga2O3...

High-quality dielectric-semiconductor interfaces are critical for reliable high-performance transistors. We report the in-situ metalorganic chemical vapor deposition (MOCVD) of Al$_2$O$_3$ on $\beta$-Ga$_2$O$_3$ as a potentially better alternative to the most commonly used atomic layer deposition (ALD). The growth of Al$_2$O$_3$ is performed in the...

In this work, the optical properties of thin-film α-Ga2O3 are examined and contrasted with those of β-Ga2O3 thin films grown on similar substrates. Thin films of α-Ga2O3 were synthesized employing mist chemical vapor deposition (mist CVD) on double-side polished c-plane sapphire. Optical properties were studied through absorbance, photoluminescence...

In this work, we use photoluminescence spectroscopy (PL) to monitor changes in the UV, blue, and green emission bands from n-type (010) Ga 2 O 3 films grown by metalorganic vapor phase epitaxy induced by annealing at different temperatures under O 2 ambient. Annealing at successively higher temperatures decreases the overall PL yield and UV intensi...

We report on the growth and characterization of metalorganic vapor-phase epitaxy-grown β -(Al x Ga 1− x ) 2 O 3 / β -Ga 2 O 3 modulation-doped heterostructures. Electron channel is realized in the heterostructure by utilizing a delta-doped β -(Al x Ga 1– x ) 2 O 3 barrier. The electron channel characteristics are studied using transfer length metho...

Performing deep level transient spectroscopy (DLTS) on Schottky diodes, we investigated defect levels below the conduction band minima (Ec) in Czochralski (CZ) grown unintentionally-doped (UID) and vertical gradient freeze (VGF)-grown Zr-doped beta-Ga2O3 crystals. In UID crystals with an electron concentration of 10^17 cm-3, we observe levels at 0....

In this work, we use photoluminescence spectroscopy (PL) to monitor changes in the UV, UV', blue, and green emission bands from n-type (010) Ga2O3 films grown by metalorganic vapor phase epitaxy (MOVPE) induced by annealing at different temperatures under O2 ambient. Annealing at successively higher temperatures decreases the overall PL yield and U...

We report on growth and characterization of metalorganic vapor-phase epitaxy-grown \b{eta}-(AlxGa1-x)2O3/ \b{eta}-Ga2O3 modulation-doped heterostructure. Electron channel is realized in the heterostructure by utilizing a delta-doped \b{eta}-(AlxGa1-x)2O3 barrier. Electron channel characteristics are studied using transfer length method, capacitance...

Currently, Fe doping in the ~10^18 cm-3 range is the most widely-available method for producing semi-insulating single crystalline beta-Ga2O3 substrates. Red luminescence features have been reported from multiple types of Ga2O3 samples including Fe-doped -Ga2O3, and attributed to Fe or N at O. Herein, however, we demonstrate that the high-intensity...

CZTSeS absorbers were prepared by two-step annealing under Ar carried H2Se gas, namely, annealing holding at 400°C then at 560°C. The additional holding results in a more compact morphology, same microstructure of phases and higher emission energy of CZTSeS absorbers. The FF as high as 79% has been achieved by improving R sh , together with the con...

In this paper, we present a method for estimating capacitances with SSTDR and a dictionary matching algorithm. We simulate a dictionary of simulated SSTDR reflections for a range of capacitances, based on parameters of the transmitted SSTDR signal, the SSTDR signal generator, and the transmission line. The measured SSTDR reflection data is compared...

This work shows wafer‐scale Ga2O3 films, which were synthesized by oxide printing of liquid metal Ga on SiO2/Si and sapphire substrates. This process enables highly uniform ∽2 nm thick films over >>1 mm² areas. The physical properties of these films (as‐deposited and after annealing in ambient conditions) are investigated by X‐ray photoelectron spe...

Cu2ZnSnS4 (CZTS) thin films were prepared by sulfurizing stacked precursors by sputtering from Cu-Zn and Cu-Sn targets which is promising for industry. The phases formation during sulfurization were investigated by varying sulfurization temperatures from 350 °C to 550 °C. At temperatures of 350 °C and 400 °C, only a thin layer ZnS formed on the sur...

CIGSeS (Cu(In,Ga)(Se,S)2, (CIGSeS)) absorbers were fabricated by sputtering a quaternary ceramic CIGSe targets and annealing in sulfur-containing atmosphere. Sulfurization was applied at various temperatures to study the variation of composition and microstructure. The performances of cells were also investigated. Sulfurization at high temperature...

The low open circuit voltage (Voc) of Cu2ZnSn(S,Se)4 (CZTSSe) thin film solar cells limits their efficiency. CZTSSe absorbers were fabricated by sputtering Cu2ZnSnS4 (CZTS) target and subsequent selenization treatment and then incorporated into solar cells. The influence of selenization temperature on the growth of the CZTSSe grains and device perf...

The CdS layers are vital for diode quality of cell devices, which have great influences on high-performance CZTSSe solar cells. Optimizing the deposition processes of CdS layers are necessary to improve the diode quality and device efficiency. In this work, CZTSSe solar cells were fabricated without and with pre-deposited CdS layers, which are refe...

Fabrication of wide band-gap (Eg) CuGaSe2 (CGSe) thin film solar cells with large area uniformity and good reproducibility is difficult, which is crucial for tandem cells. In this work, a method was proposed and investigated to overcome this problem. CGSe solar cells were fabricated by sputtering from a ternary CGSe target and post selenization tre...

The CZTSSe/CdS interface qualities are vital aspects and factors that would greatly decide the photovoltaic performance of CZTSSe solar cells. High-quality CZTSSe/CdS interfaces could reduce defect density and improve CZTSSe device performance. However, due to the inhomogeneous CZTSSe grain growth in local micro-regions during selenization, void de...

Pure kesterite Cu2ZnSnSe4 (CZTSe) absorbers with a large average grain size are vital for high-efficiency CZTSe solar cells, which are greatly influenced by the annealing atmosphere. Sputtered CZTSe precursors were annealed in the presence and absence of a selenium-containing atmosphere, and these materials were incorporated into solar cells. When...

The pure kesterite CZTSe absorbers are vital for CZTSe solar cells. However, the secondary phases such as Zn-Se, Cu-Se, Sn-Se and Cu-Sn-Se, which are almost harmful to CZTSe solar cells, often appear in the CZTSe absorbers. To investigate the phase transition pathways of as-sputtered Cu-Zn-Sn-Se precursors during selenization can provide a basis fo...

Copper Indium Gallium Selenide (Cu(In,Ga)Se2, CIGS) absorbers were fabricated by sputtering from quaternary CIGS targets and post-selenization. Potassium (K) was doped into absorbers by potassium fluoride post deposition treatment (KF-PDT). The performances of cells and the concentration distribution of alkali elements were investigated. Recombinat...

We reported a new method to fabricate submicron-thick CIGS with smooth surface by sputtering In2Se3, CuGaSe2 and Cu2Se targets with post-selenization. The influence of gallium content on the properties of CIGS thin film was evaluated by the crystallinity and the cells performance. The most suitable value of Ga content in our submicron-thick CIGS is...

Cu-rich CIGS thin films were prepared from quaternary CIGS and Cu target, and then converted into Cu-poor CIGS by depositing the Ga2Se3 layer on the Cu-rich CIGS with the subsequent annealing. In this paper, we name the process of converting Cu-rich CIGS into Cu-poor CIGS as Ga2Se3 treatment. The Ga2Se3 treatment brings out two benefits for the CIG...

CZTSSe (sulfur around 1%) absorber was prepared by sputtering on a CZTS target followed by selenization under Ar carried H2Se gas. The mechanism of CZTSSe formation was investigated by Ar annealing and selenization of sputtered CZTS precursor. The apparent decomposition temperature of CZTS precursor annealed under Ar atmosphere was between 450 °C a...

In this study, the influences of doping with antimony sulfide (Sb2S3) and metallic Sb on the properties of Cu(InGa)Se2 (CIGS) films and devices have been investigated. The incorporation of metallic Sb in CIGS films has little effect on grain growth, while the incorporation of Sb2S3 could significantly increase CIGS grain size and alter the preferen...

H2Se gas is able to enhance the grain size of CuInSe2 near the surface and have limited effects on the grains inside the thin films. The thickness of the high qualified crystal layer (HQCL) near the surface has connection with Cu content of the thin film. Increasing the Cu content can effectively enhance the length of HQCL. To enhance the crystalli...

Preparing CIGS thin films with grain size above 1 μm based on quaternary CIGS target is difficult, which is a barrier for the further enhancement of CIGS cell efficiency. We proposed a two-stage method to overcome this problem. Cu-rich CIGS thin film was prepared from quaternary CIGS and Cu target and then converted into Cu-poor CIGS by depositing...

The sputtering with post-selenization technique is a promising process for large-scale manufacturing of Cu(In,Ga)Se2 (CIGS) thin films, where the composition of precursors is important to obtaining CIGS thin films with high quality. We use the CuInSe2 thin film as an example to discuss how the content of selenium in the precursors influences the pr...

In order to investigate the effects of Sb-doping induced grain growth of Cu(InGa)Se2 (CIGS) films processed from quaternary target, thin metallic Sb layers have been deposited in the bottom, in the middle and on the top of CIGS layer, respectively. The effects of temperature on Sb-doped CIGS grain size are explored. These results demonstrate that t...

In this study, antimony sulfide (Sb2S3) thin films had been grown on Mo-coated glass substrate by evaporating metallic Sb film and subsequent annealing in nitrogen/sulfur (N2/H2S) environment. The effects of annealing temperature on phases, morphologies and compositions of thin films and corresponding devices were investigated. It was found that th...

For the two-step method of Cu(In,Ga)Se2 (CIGS) fabrication process in which the selenization step follows the CIGS precursors deposition step, H2Se gas is employed as the selenium source, which may lead to an inhomogeneous gas field and potentially hazardous working condition. In this paper, a method based on sputtering a Se-rich target to deposit...

The presence of H2Se is important for the growth of the grain size of sputtered CIGS during the selenization. However, the crystallization of the surface CIGS results in the higher density of the local area that suppressed the diffusion of H2Se in the region 600 nm beneath the surface and caused the presence of the small grains inside the CIGS. The...

The residual CuxSe phase results in shunt leakage paths in Cu-rich Cu(In,Ga)Se2 (CIGS) which can cause serious degradation in the conversion efficiency. The conductive atom force microscopy(C-AFM) was employed to obtain a direct evidence of shunt leakage paths in the Cu-rich CIGS thin film. The results reveal that CuxSe phase exists not only near t...

Two kinds of Cu(InGa)Se2(CIGS) absorbers and the corresponding solar cells have been fabricated by sputtering from Se-poor and Se-rich quaternary CIGS targets, respectively. The CIGS thin films fabricated by Se-poor target are mainly composed of chalcopyrite CIGS phase together with small amount of Cu2-xSe compound, while the CIGS thin films fabric...

Niobium doped indium-zinc oxide (INZO) film, as a new channel layer material for thin film transistors (TFTs), was deposited on glass by co- sputtering targets of IZO and Nb2O5. The optical and electronic properties of the films were investigated by means of XRD, photo luminescence (PL) and Hall effect measurements. The PL results indicate that the...

In this work, copper indium gallium selenide (CIGS) absorbers were prepared by sputtering from a copper-poor and selenium-rich target. The result shows that selenium rich absorbers can be obtained successfully after the annealing treatment under the atmosphere without selenium. The increase of annealing temperature can increase the grain size of th...

In this work, mixed powders of Cu2S, ZnS and SnS2 were used to sinter CZTS ceramic target. Thermal properties of Cu-poor and Zn-rich mixed powders were investigated by thermogravimetry and differential scanning calorimetry (TG-DSC). It has been found that the formation temperature of CZTS was not obvious in DSC curve. Obvious weight loss begun from...

Sputtering targets of CIGS quaternary ceramic were fabricated by hot-press sintering the milled powder mixture of Cu2Se, In2Se3 and Ga2Se3. When the milling time of the powders less than 4 h, the sintered targets delaminated, while the delamination disappeared with the prolonging milling time. Therefore the physico-chemical changes of the powder mi...

A Tungsten-Titanium (W-Ti) diffusion barrier was prepared on an iron (Fe) substrate by means of magnetron sputtering with subsequent annealing at different temperatures. Rutherford Backscattering Spectrometry (RBS) was used to analyze the Fe distribution in the W-Ti layer. The diffusion constant D0=3.4×10-16m2/s and the activation energy Q=43kJ/mol...

In the work, Cu2O films were prepared by middle frequency (mf) magnetron sputtering and subsequent anneals. CuO phase has been detected in a few Cu2O samples and its influences have been examined. The results show that the CuO phase can lead to a decrease of Hall mobility and change the surface morphology of the Cu2O films. The highest hall mobilit...

Cu2ZnSn(S1−x,Sex)4 (CZTSSe) absorbers with different S/(S+Se) ratios were prepared by the sputtering of a Cu2ZnSnS4 (CZTS) quaternary target on Mo-coated SLG followed by a selenization process. Influences of selenization time on properties of CZTSSe absorbers were studied in detail. Both of the crystallinity and grain size of CZTSSe absorbers were...

Copper indium gallium selenide (Cu(In,Ga)Se2, CIGS) absorbers have been prepared by sputtering a CIGS quaternary target and imposing a subsequent annealing process. The influences of annealing temperatures on the morphology, chemical composition, microstructure and electronic properties as well as phase transformations have been investigated. Scann...

In this work, we report the fabrication method of sputtering from a CIGS quaternary target to obtain high-efficiency CIGS thin-film solar-cell devices. The as-deposited CIGS absorbers are prepared by sputtering from a CIGS target and a subsequent annealing treatment under the Ar + H2Se (5% H2Se) atmosphere is applied on the absorbers. A high conver...

The as-deposited CuIn1-xGaxSe2 (CIGS) thin films were fabricated by magnetron sputtering from a quaternary CIGS target, and then the as-deposited films were annealed in a temperature range from 240℃ to 550℃. The effect of the annealing temperature on the electric properties (carrier concentration and carrier mobility) of the films was investigated...