GaN肖特基紫外探测器分析

随着科学技术的不断进步,GaN基紫外材料在社会生产已经得到了广泛地应用,这项技术的充分发展,被认为是和发光二极管、激光器具有同样作用的一种器材。基于宽禁带半导体材料的GaN紫外探测器由于具有探测波长可调控性、工艺兼容性好、构造种类比较繁多等特点,现阶段它已经成为了同行界广泛研究的一个对象。GaN肖特基结构紫外探测器因为其具有很好的相应性能与很快的反应速度所以受到业界人士的如此青睐。笔者以肖特基结构探测器的不足之处作为着手点,研究并分析了这种新型的GaN肖特基结构紫外探测器。     

GaN光导型紫外探测器

研究了以金属有机物化学气相沉积方法生长在６Ｈ－ＳｉＣ衬底上的ＧａＮ光导型紫外探测器的光电流性质。通过光电流谱的测量，获得了ＧａＮ探测器在波长２５０ｎｍ－３６０ｎｍ范围近于平坦的光电流响应，并且观察到在３６５ｎｍ（￣３．４ｅＶ）带边附近陡峭的截止边。测得ＧａＮ探测器在５Ｖ偏压下在３６０ｎｍ波长处的光电流响应度为１３３Ａ／Ｗ，并得到了其响应度与外加偏压的关系。通过拟合光电信号强度与入射光调制频率的实验     

自供能ZnO/ZnS异质结紫外探测器的性能研究

用化学浴法在ZnO纳米棒表面沉积ZnS制备出ZnO/ZnS核壳纳米棒阵列,使用SEM、XRD和XPS等手段表征了样品的形貌、结构和成分。结果表明,ZnO/ZnS核壳纳米棒阵列表面粗糙,生长致密、分布均匀,其平均直径约为150 nm。以Pt为对电极组装的自供能ZnO/ZnS异质结紫外探测器,对紫外光具有很好的探测性能,能循环工作且性能稳定。这种探测器对微弱的紫外光也有较强的响应和较高的光敏性,且随着光强度的提高光电流密度线性增大。与自供能ZnO纳米棒紫外探测器相比,ZnO/ZnS异质结紫外探测器具有更高的响应速度,上升时间和下降时间分别提高到0.02 s和0.03 s。     

我国致力于氯化镓紫外探测器研发

我国在氮化镓紫外探测器的研究上，单元探测器的系列关键技术取得了突破，研制成功了氮化镓紫外探测器。探测器的主要性能指标达到了较高水平，其中探测器的光电流响应率一般均达到0．10A／W以上，探测器的结构采用pin或pn结型或Schottky结型光电二极管方式，直径0．5mm的pn结的零偏压电阻值一般在100MΩ以上，可以用作各类紫外产品的传感器探头。     

基于溶液燃烧法制备NiO/ZnO纳米线异质结紫外探测器

本研究采用溶液燃烧法制备NiO纳米晶材料,采用水热法制备ZnO单晶纳米线,并采用提拉法将ZnO和NiO两者复合,制备出结构简单、重复性良好的NiO/ZnO异质结结构的紫外探测器。光电流测试表明其对365nm紫外光的探测灵敏度在0.9V时达到13.3。光致发光测试表明,NiO/ZnO异质结中缺陷的减少和载流子复合的抑制是其良好性能的主要原因。结果表明,燃烧法是一种有前途的制备NiO纳米晶的方法,并可用于制备性能良好的光电器件。     

CVD金刚石紫外探测器

CVD金刚石紫外探测器有极强的辐射硬度及耐腐蚀性,在宽禁带半导体紫外探测器中占有重要地位.本文主要对金刚石紫外探测器的发展进展、探测机理、电极模式及应用领域做了简要回顾.     

ZnO基紫外探测器的研究进展与关键技术

近年来,ZnO基紫外探测器由于其优异的光电特性,已成为紫外探测领域研究中的新热点之一。介绍了近年来国内外不同结构类型的ZnO基紫外探测器的研究状况,并对影响探测器性能的ZnO的光电导特性、薄膜微结构、掺杂、金半接触等关键技术进行了探讨,指出推动ZnO紫外探测器实用化进程的关键在于制备高质量的掺杂薄膜以及进一步提高器件的量子效率。     

石墨烯/硅肖特基结太阳能电池的研究进展

太阳能电池利用光伏效应直接将光能转变成电能,能有效地解决未来能源危机和环境污染,符合可持续发展的理念.传统的硅基太阳能电池存在需要高温过程,工艺复杂,发电成本无法与火电和水电相抗衡等问题.针对上述问题,近年来研究人员开发了诸多新型太阳能电池以降低制造成本,其中采用石墨烯作为透明电极的石墨烯/硅肖特基结太阳能电池被认为是新一代低成本、高效率的太阳能电池.然而,石墨烯功函数较低、方阻较高,载流子沿界面复合严重,并且平面硅反射率较高,导致石墨烯/硅肖特基结太阳能电池的效率远低于传统硅基太阳能电池.因此,近年来,主要研究重点在石墨烯掺杂改性、抑制界面处的载流子复合和降低器件的反射率等方面.目前,石墨烯/硅肖特基结太阳能电池的光电转换效率(PCE)已由1.65％提升到16.61％.目前,成功应用于提升器件性能的石墨烯掺杂剂主要有HNO3、金属纳米粒子和双(三氟甲磺酰基)酰胺(TFSA)等.其中,HNO3应用最为广泛,但其稳定性较差,采用金属纳米粒子等物理掺杂可以同时提升器件的PCE和稳定性.在石墨烯和硅之间引入Al2 O3、MoS2、量子点等界面层和表面钝化,可以有效地减少硅表面的悬空键,抑制载流子复合,从而提高器件的性能.此外,研究人员通过在石墨烯表面引入TiO2、PMMA、MgF2/ZnS等减反射膜,或在硅表面引入纳米线、多孔硅等微结构,来降低器件的反射率,提高其对光的利用率.本文总结了近年来石墨烯/硅太阳能电池的研究进展,简要介绍了器件的结构和原理,重点介绍了石墨烯掺杂、石墨烯层数选择、硅的纳米或微米结构、减反射膜和界面优化等手段,分析了目前石墨烯/硅肖特基结太阳能电池商业化所面临的问题并对其提出展望,以期为制备效率高和稳定性强的新型石墨烯/硅肖特基结太阳能电池提供一定参考.     

基于p-Se/Al2O3/n-ZnO纳米棒阵列异质结的自驱动紫外-可见光探测器

自驱动光探测器能够在无外加偏压的情况下将光信号转化为电信号, 在工业和军事领域有着广泛的应用。本研究报道了p型Se薄膜和n型ZnO纳米棒阵列异质结的可控合成以及它们作为自驱动紫外-可见光探测器的应用。由于在ZnO和Se的界面处形成的内建电场将光生电子-空穴对分离, 促使它们向相反方向传输, 最终被电极收集, 在0偏压下获得了较高的光电流(435 pA), 从而实现无线的自驱动光电探测。并且, 在Se和ZnO界面处沉积的Al₂O₃层有效降低了暗电流。最终, 此器件在500 nm的单色光下显示了高响应率55 μA·W ^-1和大比探测率5×10 ¹⁰Jones, 并表现出了极快的响应速度(上升时间0.9 ms, 衰减时间0.3 ms)。     

ZnMgO基紫外探测器的研究进展及分析

ZnO基三元合金半导体材料因其重要的带隙调制作用,已成为紫外探测器发展的一个重要方向,特别是Zn_(1-x)Mg_xO基紫外探测器,可以探测日盲区紫外光,更是受到了各国极大的关注.当前,Zn_(1-x)Mg_xO基紫外探测器大多采用MSM叉指结构,响应峰位于300nm附近,响应时间最高可达ns量级,紫外可见光抑制比亦可大于4个数量级.扼要介绍了国内外相关小组的研究进展,并着重分析了薄膜组分、结构以及探测器性能参数等.     

Post-annealing behavior of Ni/Au Schottky contact on non-polar a-plane GaN

The effects of annealing on the performance of Schottky devices on a-plane GaN/r-plane sapphire were investigated. The results show that the post-anneal Schottky barrier height (SBH) increased with increasing annealing temperature, reaching a peak increase of 43% at 500 °C. A further increase in the anneal temperature above 500 °C degraded the SBH. The ideality factor displayed a weak dependence on post-annealing temperature until rising dramatically at a post-annealing temperature of 600 °C. The degradation at 600 °C post-annealing temperature can be attributed to the formation of Nickel-Gallides. In-situ current-voltage characteristics obtained between 15 °C and 165 °C revealed that both the ideality factor and SBH were stable up to 165 °C with increasing in-situ measurement temperature.     

Schottky and pn junction cryogenic radiation detectors made of p-InSb compound semiconductor

Schottky and pn junction detectors were fabricated with p-InSb. Fabrication methods, energy spectra of ²⁴¹Am alpha particles and rise times are shown. We could observe pulses at operating temperatures up to 77 and 115 K for the Schottky and the pn junction detectors, respectively.     

Temperature-dependent properties of Pd/GaN Schottky type hydrogen sensors with Cl2 plasma surface treatments

Temperature-dependent hydrogen sensing properties of Pd/GaN Schottky type sensors with different Cl₂ plasma surface treated times are studied and demonstrated. The sensing behaviors are studied in terms of Schottky barrier height variation Δφ_B, sensing response S_r, and transient-state response times. The highest sensing response (S_r) values of 7.1 × 10⁴ and 2.12 × 10⁵ are obtained in forward- and reverse-bias voltages, respectively, upon exposure to a 10,000 ppm H₂/air gas at 30 °C. In addition, a correspondingly large Schottky barrier height variation Δφ_B of 0.38 eV is found. This could be attributed to the effective dissociation of hydrogen molecules due to a rougher Pd surface and lower baseline current. Moreover, the studied devices with Cl₂ plasma surface treatment have a stable and widespread reverse voltage operation regime. From transient-state behaviors measurement, the studied device with a 30 s plasma surface treatment shows the overshooting phenomenon and fast response (recovery) time of 4 (5) s.     

The enhanced performance of piezoelectric nanogenerator via suppressing screening effect with Au particles/ZnO nanoarrays Schottky junction

This paper describes a novel strategy to weaken the piezopotential screening effect by forming Schottky junctions on the ZnO surface through the introduction of Au particles onto the surface. With this approach, the piezoelectric-energyconversion performance was greatly enhanced. The output voltage and current density of the Au@ZnO nanoarray-based piezoelectric nanogenerator reached 2 V and 1 μA/cm², respectively, 10 times higher than the output of pristine ZnO nanoarray-based piezoelectric nanogenerators. We attribute this enhancement to dramatic suppression of the screening effect due to the decreased carrier concentration, as determined by scanning Kelvin probe microscope measurements and impedance analysis. The lowered capacitance of the Au@ZnO nanoarraybased piezoelectric nanogenerator also contributes to the improved output. This work provides a novel method to enhance the performance of piezoelectric nanogenerators and possibly extends to piezotronics and piezophototronics.

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光导型GaN/Si探测器的研制

采用ＭＯＣＶＤ技术在Ｓｉ（１１１）衬底上生长ＧａＮ薄膜,经此材料制备成光导型Ｓｉ基ＧａＮ紫外探测器。探测器的光谱响应表明,在紫外波段２５０￣３６０ｎｍ有近于平坦的光电流响应,３６３ｎｍ附近有陡峭的截止边,３５７ｎｍ波长处５Ｖ偏压下的响应度高达６．９Ａ／Ｗ。响应度与偏压的变化关系表明,４Ｖ以前为线性增加,５Ｖ后达到饱和。     

AlGaN/GaN肖特基二极管中金属电极的制备方法研究

本文主要研究AlGaN/GaN二极管制备工艺中Ohmic Contact金属和Schottky Contact金属电极的制备,主要讨论了金属电极材料的选取,退火温度和退火时间对接触电阻的影响,最后得出了Ohmic Contact的比接触电阻和TiN的淀积参数。     

Enhanced performance of GaN nanobelt-based photodetectors by means of piezotronic effects

GaN ultraviolet （UV） photodetectors （PDs） have attracted tremendous attention due to their chemical stability in harsh environments. Although Schottky- contacted GaN-based UV PDs have been implemented with better performance than that of ohmic contacts, it remains unknown how the barrier height at local Schottky contacts controls the sensors＇ performance. In this work, the piezotronic effect was employed to tune the Schottky barrier height （SBH） at local contacts and hence enhance the performances of Schottky-contacted metal-semiconductor- metal （MSM） structured GaN nanobelt （NB）-based PDs. In general, the response level of the PDs was obviously enhanced by the piezotronic effect when applying a strain on devices. The responsivity of the PD was increased by 18%, and the sensitivity was enhanced by from 22% to 31%, when illuminated by a 325 nm laser with light intensity ranging from 12 to 2 W/cm2. Carefully studying the mechanism using band structure diagrams reveals that the observed enhancement of the PD performance resulted from the change in SBH caused by external strain as well as light intensity. Using piezotronic effects thus provides a practical way to enhance the performance of PDs made not only of GaN, but also other wurtzite and zinc blende family materials.     

Self-powered, ultrafast, visible-blind UV detection and optical logical operation based on ZnO/GaN nanoscale p-n junctions

Ultrafast-response (20 μs) UV detectors, which are visible-blind and self-powered, in devices where an n-type ZnO nanowire partially lies on a p-type GaN film, are demonstrated. Moreover, a CdSe-nanowire red-light detector powered by a nanoscale ZnO/GaN photovoltaic cell is also demonstrated, which extends the device function to a selective multiwavelength photodetector and shows the function of an optical logical AND gate.     

Influence of rapid thermal annealing effect on electrical and structural properties of Pd/Ru Schottky contacts to n-type GaN

Pd/Ru metallization scheme is fabricated on n-GaN as a Schottky contact, and the electrical and structural properties have been investigated as a function of annealing temperature by current–voltage (I–V), capacitance–voltage (C–V), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) measurements. As-deposited Ru/Pd/n-GaN contact yielded Schottky barrier height (SBH) of 0.67 eV (I–V) and 0.79 eV (C–V), respectively. Further, it is observed that the Schottky barrier height increases to 0.80 eV (I–V) and 0.96 eV (C–V) for the contact annealed at 300 °C. However, both I–V and C–V measurements indicate that the barrier height slightly decreased when the contacts are annealed at 400 °C and 500 °C. From the above observations, the optimum annealing temperature for Pd/Ru Schottky contact is 300 °C. Norde method is also employed to extract the barrier height of Pd/Ru Schottky contacts which are in good agreement with those obtained by the I–V technique. X-ray photoelectron spectroscopy results shows that the Ga 2p core-level shift towards the low-energy side for the contact annealed at 300 °C compared to the as-deposited contact. Based on the XPS and XRD results, the reason for the increase in SBH upon annealing at 300 °C could be attributed to the formation of gallide phases at the Ru/Pd/n-GaN interface vicinity. The AFM results showed that the overall surface morphology of the Pd/Ru Schottky contacts on n-GaN is fairly smooth. The above observations reveal that the Pd/Ru Schottky contact is attractive for high-temperature device applications.