以铝作过渡层的c轴取向Si基ZnO晶体薄膜的生长及其肖特基二极管的研制

利用直流反应磁控溅射方法在金属Al过渡层上沉积了Si基Zn O晶体薄膜,并利用X射线衍射、扫描电子显微镜和扩展电阻测试仪对Zn O薄膜的晶体质量和电学性能进行了分析.结果表明,Zn O薄膜具有高度的c轴取向,样品表明光洁、平整,薄膜与衬底之间有清晰的过渡区.在此Zn O薄膜上成功地制备了肖特基二极管的原型器件,室温下的I- V测试结果表明该Au/ Zn O/ Al肖特基二极管具有明显的整流特性     

MOCVD法制备ZnO同质发光二极管

在n型ZnO体单晶片上, 首次采用N等离子体辅助金属有机化学气相沉积方法外延生长了p型ZnO薄膜，制成了同质ZnO的发光二极管(LED)原型器件；在室温下，观察到同质ZnO的LED施加电压后由电注入激发出紫外至绿光波段的光谱.     

Realization of intrinsic p-type ZnO thin films by metal organic chemical vapor deposition

P-type ZnO thin films were grown on sapphire substrates with and without nitrous oxide (N₂O) by metal organic chemical vapor deposition (MOCVD). The intrinsic p-type ZnO films were achieved by controlling the Zn:O ratio in the range of 0.05–0.2 without N₂O flow. Secondary ion mass spectroscopy (SIMS) showed that the films contained little or no nitrogen (N) impurities for all samples. The p-type behavior of the samples should be due to the intrinsic acceptor-like defects V_Zn, for ZnO film grown without nitrous oxide, and N, occupying O sites as acceptors for ZnO film grown with nitrous oxide. The best p-type ZnO film has low resistivity of 0.369 Ω-cm, high carrier density of 1.62×10¹⁹ cm⁻³, and mobility of 3.14 cm²/V-s. The obtained p-type ZnO films possess a transmittance of nearly 100% in the visible region and strong near-band-edge emission.     

Ultraviolet ZnO Photodetectors with High Gain

Fabrication and characterization of metal-semiconductor-metal ultraviolet(MSM UV) photodetector based on ZnO ultra thin(nano scale) films with Pd Schottky contact are reported.The ZnO thin film was grown on glass substrate by thermal oxidation of pre-deposited zinc films using vacuum deposition technique.With applied voltage in the range from -3V to 3V,the contrast ratio,responsivity,and detectivity for an incident radiation of 0.1 mW at 365 nm wavelength were estimated.The proposed device exhibited a high ...     

Synthesis of highly selective and sensitive Cu-doped ZnO thin film sensor for detection of H2S gas

Copper (Cu) doped zinc oxide (ZnO) thin films were successfully prepared by a simple sol-gel spin coating technique. The effect of Cu doping on the structural, morphology, compositional, microstructural, optical, electrical and H₂S gas sensing properties of the films were investigated by using XRD, FESEM, EDS, FTIR, XPS, Raman, HRTEM, and UV–vis techniques. XRD analysis shows that the films are nanocrystalline zinc oxide with the hexagonal wurtzite structure and FESEM result shows a porous structured morphology. The gas response of Cu-doped ZnO thin films was measured by the variation in the electrical resistance of the film, in the absence and presence of H₂S gas. The gas response in relation to operating temperature, Cu doping concentration, and the H₂S gas concentration has been systematically investigated. The maximum H₂S gas response was achieved for 3 at% Cu-doped ZnO thin film for 50 ppm gas concentration, at 250 °C operating temperature.     

Investigation on doping behavior of copper in ZnO thin film

An experiment to determine the electronic and chemical states of Cu in a ZnO crystal was performed using Hall measurement, X-ray photoelectron spectroscopy (XPS) and low-temperature photoluminescence (PL). Cu atoms showed different behaviors in the ZnO matrix as a function of oxygen gas pressure. Metallic copper (Cu⁰)-related Cu 2p_3/2 peak was observed in highly n-type ZnO:Cu film deposited in 10 mTorr. In the Cu-doped p-type ZnO film prepared in 50 mTorr, Cu_Zn¹⁺-related peak and small Cu_Zn²⁺-related satellite peak exhibited and the optical acceptor binding energies of Cu3d⁹ and Cu3d¹⁰ were 173 and 213 meV, respectively.     

氮气退火对NiO/ZnO:Al薄膜PN结的影响

利用磁控溅射法,在ITO玻璃基底上沉积NiO薄膜和ZnO:Al(Al掺杂的ZnO或AZO)薄膜,制备具有半导体特性的NiO/ZnO:Al透明异质结二极管。使用UV-1700型分光光度计、KEITHLEY4200-SCS半导体测试仪、JSM-6490LV型扫描电子显微镜等分析氮气退火对NiO/ZnO:Al薄膜性能的影响。实验结果表明:500℃退火范围内,NiO薄膜的透过率随退火温度的升高单调上升,500℃时透过率在80%以上,NiO/ZnO:Al薄膜的透过率明显提高;在400℃时,NiO/ZnO:Al薄膜整流特性最佳。     

ZnO:Ag薄膜的制备及其光学性能研究

采用蒸镀与氧化二步法,以高纯混合金属Zn:Ag作蒸发源,在石英衬底上沉积Zn:Ag金属薄膜,经不同热氧化处理生长Ag掺杂ZnO薄膜。结果显示,以Ag含量为质量分数3%的蒸发源沉积的Zn:Ag薄膜经500℃氧化后,生成的ZnO:Ag薄膜在380 nm附近出现很强的近带边紫外发光峰,在438~470 nm附近出现较弱的深能级缺陷发光峰,该薄膜在360 nm有接近垂直的吸收边,其载流子浓度为1.810×1021cm–3,表现出p型导电特性和较好的光学质量。     

Characterization and Stability of Na-doped p-type ZnO Thin Films Preparation by Reactive DC Magnetron Sputtering

Na-doped p-type ZnO thin films have been realized by DC reactive magnetron sputtering with a set of metal-Zn targets doped with various Na contents and under different substrate temperatures, respectively. Hall effect measurement, field-emission SEM, X-ray diffraction and optical transmission were carried out to investigate the effects of Na content and substrate temperature on the properties of p-type films. Results indicate that all the Na-doped ZnO films are strongly (002) oriented, and have an average t...     

Enhancement of effective barrier height in Ti-silicon Schottky diode using low-energy ion implantation

Increasing the effective barrier height in a Ti-p-type silicon Schottky diode has been achieved by means of low-energy ion implantation to introduce a thin inversion layer on silicon substrate. It is shown theoretically that effective barrier height equal to the energy bandgap can be obtained in such structure if the thickness and dopant density of the implanted layer are properly chosen. Experimental results for several titanium (Ti) on phosphorus implanted p-type silicon Schottky diodes show that effective barrier heights were increased from 0.6 eV for the Ti-p Si Schottky diode to 0.96 eV for a Ti-n-p-Si Schottky diode with a phosphorus-implanted layer thickness of 400 Å and dose of 1.26 × 10¹²cm^-2. Good agreement is obtained between the calculated and the measured barrier height for several Ti-n-p silicon Schottky diodes.     

P型ZnO薄膜制备和掺杂的研究进展

ZnO作为第三代半导体功能材料,一直受到国内外的广泛关注.高质量的p型掺杂是基于光电器件应用的关键.综述了获得p型ZnO薄膜的制备方法和掺杂技术的研究进展,讨论了目前生长高质量的p型ZnO薄膜存在的困难,并对不同方法制备的p型ZnO薄膜的特点进行了比较分析.     

Electrically conductive anti‐reflecting nanostructure for chalcogenide thin‐film solar cells

Electrically conducting aluminum (Al)‐doped ZnO nanorods (NRs) film has been introduced as an anti‐reflective (AR) layer for effective light trapping in chalcogenide thin‐film solar cells. Results indicate that the Al‐doping significantly reduced the electrical contact resistance between the Ag top electrode and the AR layer. The Al‐doped ZnO NRs exhibited low average reflectance (4.5%) over the entire visible and near‐infrared range, and changed the nature of electrical contact between the Ag electrode and the AR layer from Schottky to Ohmic. Finally, the CuInS₂ solar cell coated with the Al‐doped ZnO NRs exhibited huge enhancement in photovoltaic efficiency from 9.57% to 11.70% due to the lowering series resistance and the increase in the short‐circuit current density, when compared with that of a solar cell without the AR layer. Copyright © 2014 John Wiley & Sons, Ltd.     

Cu掺杂ZnO薄膜光学性质的研究

为了制备结晶质量好的Cu掺杂ZnO薄膜,研究其结构和光学性质,采用脉冲激光沉积方法,在Si衬底上选择不同的衬底温度来制备薄膜。实验成功制得了结晶质量较好的Cu掺杂ZnO薄膜。利用X射线衍射仪、扫描电子显微镜和荧光分光光度计对样品进行了测量和分析。所制备的样品均表现出高度的c轴择优取向,衬底温度为300℃时,薄膜表面形貌均匀致密;在样品的光致发光谱中,发现样品除了在380nm附近出现紫外发光峰外,在460nm附近出现了蓝光发光峰,真正意义上实现了ZnO薄膜的蓝光发射。结果表明,衬底温度对其晶体质量有较大影响。     

P-type ZnO thin films prepared by in situ oxidation of DC sputtered Zn3N2:Ga

The feasibility of a new fabrication route for N and Ga codoped p-type ZnO thin films on glass substrates, consisting of DC sputtering deposition of Zn3N2:Ga precursors followed by in situ oxidation in high purity oxygen, has been studied. The effects of oxidation temperature on the structural, optical and electrical properties of the samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), optical transmittance and Hall effect measurements. The results were compared to a control film without Ga. XRD analyses revealed that the Zn3N2 films entirely transformed into ZnO films after annealing Zn3N2 films in oxygen over 500 ℃ for 2 h. Hall effect measurements confirmed p-type conduction in N and Ga codoped ZnO films with a low resistivity of 19.8 Ω·cm, a high hole concentration of 4.6 × 1018 cm-3 and a Hall mobility of 0.7 cm2/(V·s). These results demonstrate a promising approach to fabricate low resistivity p-type ZnO with high hole concentration.     

Co与Cu掺杂ZnO磁性薄膜的溶胶-凝胶旋涂法制备

用溶胶-凝胶旋涂法在玻璃衬底上制备了Co,Cu单掺杂及(Co,Cu)共掺杂ZnO薄膜.磁性测量表明,无论是单掺还是共掺的ZnO薄膜都具有室温铁磁性,且Co掺杂和共掺杂ZnO薄膜的磁性相近,而Cu单掺ZnO薄膜磁性稍弱一点.用原子力显微镜和X射线衍射研究了Co,Cu掺杂对ZnO薄膜表面形貌和晶体结构的影响,在薄膜中没有发现第二相和磁性团簇的存在,且所有ZnO薄膜样品都存在(002)择优取向.室温光致发光测量在所有的样品中都观察到447和482 nm附近的蓝光发射,认为是由于氧空位浅施主能级上的电子到价带上的跃迁所导致的.     

Ultraviolet Photodetection Properties of a Pt Contact on a Mg<Subscript>0.1</Subscript>Zn<Subscript>0.9</Subscript>O/ZnO Composite Film

We report on the ultraviolet (UV) photodetection properties of a Pt contact on a sol-gel Mg_0.1Zn_0.9O/ZnO composite structure on a glass substrate. In the dark, the current–voltage (I–V) characteristics between the Pt and Ag contacts on the top of the ZnO film were linear while that on the Mg_0.1Zn_0.9O/ZnO composite film were rectifying, suggesting the formation of a Schottky diode on the latter. The ideality factor, n, and the reverse leakage current density, J _R , of the Schottky diode were greater than 2 and 2.36 × 10⁻² A cm⁻² at −5 V, respectively. Under ultraviolet light, the I–V characteristics become linear. The maximum photo-to-dark current ratio observed was about 63. The composite film showed good sensitivity to UV light with wavelengths of less than 400 nm, though the photoresponse process was found to be slow.     

A p-silicon nanowire/n-ZnO thin film heterojunction diode prepared by thermal evaporation

This paper represents the electrical and optical characteristics of a SiNW/ZnO heterojunction diode and subsequent studies on the photodetection properties of the diode in the ultraviolet （UV） wavelength region. In this work, silicon nanowire arrays were prepared on p-type （100）-oriented Si substrate by an electroless metal deposition and etching method with the help of ultrasonication. After that, catalyst-free deposition of zinc oxide （ZnO） nanowires on a silicon nanowire （SiNW） array substrate was done by utilizing a simple and cost-effective thermal evaporation technique without using a buffer layer. The SEM and XRD techniques are used to show the quality of the as-grown ZnO nanowire film. The junction properties of the diode are evaluated by measuring current-voltage and capacitance-voltage characteristics. The diode has a well-defined rectifying behavior with a rectification ratio of 190 at -t-2 V, turn-on voltage of 0.5 V, and barrier height is 0.727 eV at room temperature under dark conditions. The photodetection parameters of the diode are investigated in the bias voltage range of ± 2 V. The diode shows responsivity of 0.8 A/W at a bias voltage of 2 V under UV illumination （wavelength = 365 nm）. The characteristics of the device indicate that it can be used for UV detection applications in nano-optoelectronic and photonic devices.     

Current–voltage characteristics of AlCdO Schottky contact on the polished and unpolished p-type Si surfaces with and without light illumination

In this study, the current-voltage characteristics of the AlCdO/unpolished p-type Si and AlCdO/polished p-type Si Schottky diodes with and without light illumination were examined. It is found that the Schottky barrier height (the series resistance) of the AlCdO/unpolished p-type Si Schottky diode is higher (lower) than that of the AlCdO/polished p-type Si Schottky diode. The power conversion efficiency of the AlCdO/p-type Si devices in the light (AM 1.5 G, 100 mW/cm²) was improved by increasing built-in potential at the AlCdO/p-type Si interfaces and reducing the device series resistance and surface reflectivity. It is shown that the device surface roughness plays an essential role in improving the device performance.     

Characterization and performance of Schottky diode based on wide band gap semiconductor ZnO using a low-cost and simplified sol-gel spin coating technique

In this study, a Schottky diode based on wide band gap semiconductor ZnO was fabricated on p-type Si substrate using sol-gel spin coating method. Al/ZnO/p-Si diode indicates a rectification behavior. At lower voltages, the forward current of the diode was found to obey the intrinsic thermally generated charge carriers and at relatively higher voltages, the current mechanism of the diode is controlled by a space charge limited conduction mechanism. Under reverse bias conditions, the current-voltage characteristics of the diode exhibit the lower current as compared under forward bias, indicating the existence of a current limitation mechanism induced by two field lowering mechanisms which are Poole-Frenkel and Schottky mechanisms. The parameters, series resistance R_S, the ideality factor n and the barrier height φ_B0 of the diode were determined by performing different plots obtained from the experimental forward bias current-voltage. The capacitance measurements show that the values of capacitance were almost independent of the forward bias under various frequencies. The higher values of the capacitance at low frequencies were attributed to the excess capacitance resulting from the interface states in equilibrium with the ZnO.     

Strain Modulation in Graphene/ZnO Nanorod Film Schottky Junction for Enhanced Photosensing Performance

Strain modulation in flexible semiconductor heterojunctions has always been considered as an effective way to modulate the performance of nanodevices. In this work, a graphene/ZnO nanorods film Schottky junction has been constructed. It shows considerable responsivity and fast on‐off switch to the UV illumination. Through utilizing the piezopotential induced by the atoms displacement in ZnO under the compressive strain, 17% enhanced photosensing property is achieved in this hybrid structure when applying ?0.349% strain. This performance improvement can be ascribed to the Schottky barrier height modification by the strain‐induced piezopotential, which results in the facilitation of electron–hole separation in the graphene/ZnO interface. An energy band principle as well as a finite element analysis is proposed to understand this phenomenon. The results here provide a facile approach to boost the optoelectronic performance of graphene/ZnO heterostructure, which may also be applied to other Schottky junction based hybrid devices.