ZnO异质结光电器件的制备及其性能研究

发布时间：2018-07-10 06:43

本文选题：氧化锌 + 异质结　；参考：《北京科技大学》2016年博士论文

【摘要】：紫外光电器件在绿色照明、光通信和紫外探测等方面有着广泛的应用和巨大的前景。第三代新型半导体氧化锌(ZnO)材料是一种重要的Ⅱ-Ⅵ族直接带隙半导体材料,室温下ZnO的禁带宽度为3.37 eV,其激子束缚能高达60 meV,远大于室温’下的热激活能26 meV。此外,ZnO具有良好的光电导特性,光学增益系数高达320 cm-1,对紫外光有较强的吸收能力,同时还具有良好的压电和热电特性,而且原料丰富、成本低、无毒、环境友好。因此作为半导体紫外光电器件的重要材料,ZnO在电致发光和紫外探测领域具有重要应用潜力。本论文主要研究了薄膜和纳米棒阵列ZnO材料的光电性质。基于ZnO/p-GaN薄膜异质结,我们研究了其在近紫外波段的发光现象和光伏效应,并以此设计实现了蓝光发光二极管和自驱动高速紫外光探测器件：基于ZnO纳米棒阵列/NiO异质结,深入研究了异质结的自驱动光电响应特性：基于ZnO/Spiro-MeOTAD有机无机杂化异质结,系统研究了该异质结的自驱动光电响应性能以及应变对器件光响应性能的调控规律。通过优化实验条件和调控合成参数,分别利用磁控溅射技术和水热合成法制备了ZnO薄膜与ZnO纳米棒阵列。研究了水热法前驱液浓度对ZnO纳米棒阵列形貌的影响规律。生长的ZnO薄膜和ZnO纳米棒阵列都具有六方纤锌矿结构,沿[0001]极性轴方向取向生长,同时光学特性优异,具有较强的禁带边发射峰和弱的可见光发射峰。霍尔效应测试得到ZnO薄膜的电子浓度和电子迁移率分别为3.13×1018 cm-3和14.6cm2V-1 s-1。研究了ZnO薄膜与p型GaN薄膜形成的异质结发光二极管的电致发光规律。该二极管器件的串联电阻约为102Ω,发光阈值电压约为2.7V。电致发光谱表明,当电压高于2.7V时,实现了二极管稳定高亮的460nm蓝光输出,发光效率约0.89%,并且发光强度和注入电流遵循幂指数法则,即L∝Im,低注入电流(10mA)时L-I曲线呈超线性关系(m=1.35),而高注入电流下(10mA)几乎成线性关系(m=0.95),m非常接近1.0表明非辐射复合缺陷对器件光发射的影响较小。研究了基于ZnO薄膜和p型GaN薄膜的全无机pn结紫外探测器的自驱动光电响应性能。该异质结器件在紫外光波段具有优异的光伏效应,1.0 mW/cm2紫外光入射时,可得到开路电压和短路电流分别为1.32 V和5.55μA。光电流-时间(I—t)响应特性测试结果表明,该器件对514 nm的可见光没有响应,而365 nm和254 nm两种波长的紫外光辐照时,光电流的响应快速、连续且可重复,响应时间和恢复时间均小于0.3s。光电流随着两种波长紫外光光强的增大而线性增大,且没有出现饱和现象。光谱响应度曲线测试结果显示该器件具有高达102的紫外-可见光抑制比,响应度的最大值高达25mA/W,该值远大于之前已报道的自驱动紫外探测器的值。研究了ZnO纳米棒阵列和p型NiO薄膜形成的全无机pn结紫外探测器的自驱动光电响应性能。光电测试结果表明,该器件可工作在光伏模式,零伏偏压下,在波长355 nm功率3.2 mW/cm2的紫外光辐照时可产生显著的约0,3μA光电流。在0.1 mV正向偏压下,紫外光开启和关闭时光电流呈正负交替变化,表明是一种快速开关二进制响应,主要归因于ZnO/NiO器件的光伏特性和低的开启电压。零伏偏压下器件的响应度随着紫外光辐照功率的增加先快速增加然后逐渐减小,0.4 mW/cm2辐照助率下达到了最大值0.44 mA/W。研究了柔性衬底上ZnO薄膜与p型Spiro-MeOTAD形成的有机无机杂化异质结紫外探测器的自驱动光电响应性能及其应变调控规律。电学性能测试表明,异质结呈现典型的非线性整流特性,开启电压较低(～0.8V),±1V偏压下的整流比高达7.69×102。光电测试结果表明,器件在紫外光辐照下具有明显的光响应和显著的光伏效应。器件在零伏偏压下的光电流响应快速、连续、可重复且没有明显衰减,响应时间和恢复时间小于0.2s。应变对ZnO/Spiro-MeOTAD器件光电响应性能的影响规律表明,当施加的拉伸应变逐渐增加时,器件的光电流、光响应度和比探测度逐渐增大,当拉伸应变增加到0.753%时,光电流、光响应度和比探测度相比无应变时增加了近1倍；相反地,压缩应变增加时光电流、光响应度和比探测度减小。这主要是由于ZnO在不同应变下产生的压电极化电荷会影响异质结耗尽区内建电场的强弱,从而导致光生电子空穴对的分离效率被提高或抑制造成的。
[Abstract]:UV optoelectronic devices have extensive applications and great prospects in green lighting, optical communication and ultraviolet detection. The third generation of new semiconductor Zinc Oxide (ZnO) material is an important type of II VI direct band gap semiconductor material. The band gap of ZnO at room temperature is 3.37 eV, and its exciton binding energy is up to 60 meV, far greater than room temperature. The thermal activation energy is 26 meV.. In addition, ZnO has good photoconductivity, optical gain coefficient up to 320 cm-1, strong absorption capacity to ultraviolet light, good piezoelectricity and thermoelectric properties, and rich in raw materials, low cost, non-toxic and environmentally friendly. Therefore, ZnO is an important material for semiconductor UV optoelectronic devices. The optical and UV detection fields have important potential applications. This paper mainly studies the photoelectric properties of the thin film and nanorod array ZnO materials. Based on the ZnO/p-GaN thin film heterojunction, we have studied its luminescence and photovoltaic effect in the near ultraviolet band, and designed the blue light emitting diode and the self driven high-speed ultraviolet detection. Device: Based on the ZnO nanorod array /NiO heterojunction, the self driven photoelectric response characteristics of the heterojunction are studied in depth: Based on the ZnO/Spiro-MeOTAD organic-inorganic hybrid heterojunction, the self driven photoelectric response and the regulation of the response performance of the heterostructure to the optical response of the device are systematically studied. ZnO films and ZnO nanorod arrays were prepared by magnetron sputtering and hydrothermal synthesis. The influence of the concentration of hydrothermal precursor on the morphology of ZnO nanorods was studied. The growth of ZnO and ZnO nanorods arrays had six zinite structures, along the direction of the 0001] polar axis, and the optical properties of the nanorods. Excellent, strong band edge emission peak and weak visible light emission peak. The electron concentration and electron mobility of ZnO film are 3.13 x 1018 cm-3 and 14.6cm2V-1 s-1. respectively. The electroluminescence of the heterojunction light emitting diode of ZnO film and P type GaN film is studied. The series resistance of the diode device is in series. About 102 Omega, the luminescence threshold voltage of about 2.7V. electroluminescence spectrum shows that when the voltage is higher than 2.7V, the high brightness 460nm blue light output of the diode is achieved, the luminous efficiency is about 0.89%, and the luminescence intensity and injection current follow the power exponent rule, that is, L Im, and low injection current (10mA), the L-I curve is superlinear (m=1.35), and high injection electricity The flow (10mA) is almost linear (m=0.95), and M is very close to 1. The effect of non radiation composite defects on the optical emission is small. The self driving photoelectric response of all inorganic PN junction UV detectors based on ZnO film and P GaN thin film is studied. The heterojunction device has excellent photovoltaic effect and 1 mW/cm2 violet in ultraviolet band. When the external light is incident, the test results of the open circuit voltage and the short circuit current of 1.32 V and 5.55 mu A. photocurrent time (I - t) show that the device has no response to the visible light of 514 nm, while the 365 nm and 254 nm two wavelengths are irradiated by ultraviolet light, and the photocurrent should be fast, continuous and repeatable, response time and recovery time. The average less than 0.3s. photocurrent increases linearly with the increase of ultraviolet light intensity of two wavelengths, and does not appear to be saturated. The spectral response curve test results show that the device has up to 102 UV visible light rejection ratio and the maximum response degree is up to 25mA/W, which is much larger than the value of the previously reported UV detector. The self driving photoelectric response performance of the all inorganic PN junction UV detector formed by ZnO nanorod array and P NiO thin film is studied. The photoelectric test results show that the device can work in the photovoltaic mode, the zero volt bias, and can produce a significant approximately 0,3 micron photocurrent at the wavelength of 355 nm power of 3.2 mW/cm2 at the zero volt voltage. In the 0.1 mV positive bias voltage, the device can produce a positive bias voltage at 0.1 mV positive bias. At the same time, the time current of UV opening and closing is positive and negative alternately, indicating that it is a fast switching binary response, which is mainly attributed to the photovoltaic characteristics and low open voltage of the ZnO/NiO device. The response degree of the device under the zero volt bias increases rapidly and gradually decreases with the increase of ultraviolet radiation power, and the 0.4 mW/cm2 irradiation assistance The maximum value of 0.44 mA/W. is reached to study the self driving photoelectric response performance and strain regulation of the organic and inorganic hybrid heterojunction UV detector formed by ZnO thin film on the flexible substrate and P Spiro-MeOTAD. The electrical properties test shows that the heterojunction presents a typical nonlinear rectifying characteristic, the opening voltage is lower (to 0.8V), and the + 1V bias voltage is under the bias voltage. The 7.69 x 102. photoelectric test results show that the device has obvious light response and significant photovoltaic effect under UV irradiation. The photocurrent response of the device under zero voltage bias is fast, continuous, repeatable and without obvious attenuation, and the response time and recovery time are smaller than the photoelectric response of the 0.2s. strain to the ZnO/Spiro-MeOTAD device. The effect of the performance shows that when the tensile strain is increased gradually, the photocurrent, the light response degree and the specific detection measure gradually increase. When the tensile strain increases to 0.753%, the photocurrent, the light response degree and the specific detection measure increase nearly 1 times when compared with the non strain measurement. On the contrary, the compression strain increases the time current, the light response degree and the ratio exploration. This is mainly due to the effect of the piezoelectric polarization charge of ZnO under different strains on the strength of the built electric field in the heterojunction depleted region, which leads to the increase or suppression of the separation efficiency of the photogenerated electron hole pair.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN23;TN304.21

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