(100)定向CVD金刚石薄膜的制备及其电学性能

采用HFCVD制备金刚石薄膜的方法,以乙醇为碳源,氢气为载气,在适当的衬底温度下,合成出具有(100)晶面取向均匀生长的金刚石薄膜.SEM,XRD和Raman分析表明,所合成的金刚石薄膜是高质量的多晶(100)取向膜,厚度均匀、化学性能稳定,结构和性能与天然金刚石相接近.研究了室温下(100)取向金刚石薄膜的暗电流-电压特性、稳态55Fe 5.9keV X射线辐照下的响应和电容-频率特性.结果表明,退火后(100)取向多晶金刚石薄膜具有较低的暗电流和较高的X射线响应;高频下,电容和介电损耗都很小且趋于稳定,不随频率的变化而变化.     

(100)定向CVD金刚石薄膜的制备及其电学性能

采用HFCVD制备金刚石薄膜的方法,以乙醇为碳源，氢气为载气，在适当的衬底温度下，合成出具有(100)晶面取向均匀生长的金刚石薄膜．SEM，XRD和Raman分析表明,所合成的金刚石薄膜是高质量的多晶(100)取向膜，厚度均匀、化学性能稳定,结构和性能与天然金刚石相接近．研究了室温下(100)取向金刚石薄膜的暗电流电压特性、稳态55Fe 5.9keV X射线辐照下的响应和电容频率特性．结果表明，退火后(100)取向多晶金刚石薄膜具有较低的暗电流和较高的X射线响应；高频下，电容和介电损耗都很小且趋于稳定，不随频率的变化而变化．     

AlGaN/GaN异质结紫外探测器

采用P-AlxGa1-xN/i-GaN/n-GaN异质结构成功制备了含铝组分分别为0.1和0.07的正照射可见盲紫外探测器,并分别测试了它们的伏安特性曲线和光电响应光谱.对于Al分为0.1的器件,在零偏压处出现了极低的暗电流密度,表明器件具有非常高的信噪比.高分辨率X射线衍射仪对材料的测试结果表明,高铝组分(0.1)窗口层薄膜材料的晶体质量较差,导致暗电流增大,而其窗口层的窗口选择作用则可以得到较高的响应率和较宽的响应波段.     

n-on-p结构深台面延伸波长InGaAs探测器的ICPCVD钝化工艺

采用ICP刻蚀(inductively coupled plasma etching)工艺制备了深台面n-on-p结构的可响应到2.4μm的延伸波长8×1元线列In Ga As探测器.器件表面采用ICP源激发的N2等离子体进行处理,然后再使用ICPCVD(inductively coupled plasma chemical vapor deposition)沉积一层Si Nx薄膜的钝化工艺.不同面积光敏元器件的电流—电压特性分析显示器件在常温和低温下侧面电流均得到有效抑制,激活能分析显示了器件优异的暗电流特性,在-10 m V偏压下,在200 K和300 K温度下暗电流密度分别为94.2 n A/cm2和5.5×10-4A/cm2.     

用于远红外探测的Si:P阻挡杂质带红外探测器研制

提出了全外延技术方案制备阻挡杂质带薄膜,避免了离子注入制备背电极层影响外延薄膜质量的技术难点.基于硅器件工艺设计制作了Si:P阻挡杂质带红外探测器.测量了器件的光电流响应谱和暗电流特性曲线,指认了叠加在光电流响应谱上的尖锐杂质峰对应阻挡层中磷原子的杂质跃迁.研究了器件在低温下小偏压范围内的暗电流起源.通过对计算结果分析,排除了该区域暗电流起源于热激发电导和跳跃式电导的可能,指出暗电流来自器件对冷屏的光电响应.器件工作温度5 K,工作偏压1.6 V时,响应波段覆盖2.5~40μm,峰值波长28.8μm,峰值响应率20.1 A/W,峰值探测率3.7×1013cm·Hz1/2/W(背景光子通量低于1013ph/cm2·s).     

InAs/GaSb II类超晶格红外探测器光敏元蚀刻表面特性

采用刻蚀技术形成台面结构的红外探测器光敏元,其表面漏电流和器件热稳定性与半导体蚀刻表面的特性密切相关。对制备的InAs/GaSb Ⅱ类超晶格中波红外探测器台面蚀刻区域特性进行了研究报道。通过台面结栅控结构和快速热退火相结合的实验研究,发现热退火处理使得样品在温度80 K,偏置电压-0.05 V下的暗电流密度从2.17×10~(-7)A/cm~2上升至6.96×10~(-5)A/cm~2,并且有无退火样品的暗电流随偏置电压变化表现出明显的不同。退火导致光敏元台面侧壁电荷密度上升2.76×10~(12)cm~(-2),引起了表面漏电流的增加,利用X射线光电子能谱(XPS)发现退火后台面蚀刻区域Sb单质含量增加。     

AlGaN/GaN异质结紫外探测器

采用p-AlxGa1-xN/i-GaN/n- GaN异质结构成功制备了含铝组分分别为0.1和0.07的正照射可见盲紫外探测器，并分别测试了它们的伏安特性曲线和光电响应光谱。对于Al组分为0.1的器件，在零偏压处出现了极低的暗电流密度，表明器件具有非常高的信噪比。高分辨率X射线衍射仪对材料的测试结果表明，高铝组分(0.1)窗口层薄膜材料的晶体质量较差，导致暗电流增大，而其窗口层的窗口选择作用则可以得到较高的响应率和较宽的响应波段。     

长波InAs/GaSb II类超晶格红外探测器

报道了50％截止波长为12.5μm的InAs/GaSb Ⅱ类超晶格长波红外探测器材料及单元器件.实验采用分子束外延技术在GaSb衬底上生长超晶格材料.吸收区结构为15ML(InAs)/7ML(GaSb),器件采用PBIN的多层异质结构以抑制长波器件暗电流.在77K温度下测试了单元器件的电流-电压(I-v)特性,响应光谱和黑体响应.在该温度下,光敏元大小为100μm×100μm的单元探测器RmaxA为2.5Ωcm2,器件的电流响应率为1.29A/W,黑体响应率为2.1×109cmHz12/W,11μm处量子效率为14.3％.采用四种暗电流机制对器件反向偏压下的暗电流密度曲线进行了拟合分析,结果表明起主导作用的暗电流机制为产生复合电流.     

Si基HgCdTe变面积光伏探测器的变温特性研究

通过变面积Si基HgCdTe器件变温I-V测试和暗电流特性拟合分析,研究了不同偏压下n-on-p型Si基HgCdTe光伏器件的暗电流成分与Si基HgCdTe材料少子扩散长度和少子寿命随温度的变化规律.在液氮温度下,随着反向偏压的增大器件的表面漏电流在暗电流中所占比重逐渐增加.在零偏压下,当温度低于200 K时材料的少子...     

Ge/Si SACM-APD器件分析

Ge/Si吸收区-电荷区-倍增区分离(SACM)结构的APD作为一种新型光电探测器已成为硅基APD器件研究的重点.对SACM Ge/Si型APD器件的基本结构及其主要特性参数,包括量子效率、响应度、暗电流等进行了理论分析及仿真验证.实验结果表明:在给定的器件参数条件下,所设计的APD器件的雪崩击穿电压为25.7 V,最大内部量子效率为91%,单位增益下响应度峰值为0.55 A/W,在750~1 500 nm范围内具有较高响应度,其峰值波长为1 050 nm;在高偏压以及高光照强度情况下,倍增区发生空间电荷效应从而导致增益降低.     

Electrical properties of silver Schottky contacts to ZnO thin films

ZnO thin films are deposited on Al/Si substrates by the pulsed laser deposition （PLD） method. The XRD and SEM images of films are examined. Highly c-axis oriented ZnO thin films which have uniform compact surface morphology are fabricated. The size of surface grains is about 30 nm. The Schottky barrier ultraviolet detectors with silver Schottky contacts are made on ZnO thin films. The current-voltage characteristics are measured. The ideality contact factor between Ag and ZnO film is 1.22, while the barrier height is 0.908 e V. After annealing at 600 ℃ for 2h, the ideality factor is 1.18 and the barrier height is 0.988 eV. With the illumination of 325 nm wavelength UV-light, the photocurrent-to-dark current ratios before and after annealing are 140.4 and 138.4 biased at 5 V, respectively. The photocurrents increase more than two orders of magnitude over the dark currents.     

Ultra-Low Dark Current Organic–Inorganic Hybrid X-Ray Detectors

Organic-inorganic hybrid semiconductors are an emerging class of materials for direct conversion X-ray detection due to attractive characteristics such as high sensitivity and the potential to form conformal detectors. However, existing hybrid semiconductor X-ray detectors display dark currents that are 1000–10 000× higher than industrially relevant values of 1–10 pA mm⁻². Herein, ultra-low dark currents of <10 pA mm⁻², under electric fields as high as ≈4 V µm⁻¹, for hybrid X-ray detectors consisting of bismuth oxide nanoparticles (for enhanced X-ray attenuation) incorporated into an organic bulk heterojunction consisting of p-type Poly(3-hexylthiophene-2,5-diyl) (P3HT) and n-type [6,6]-Phenyl C71 butyric acid methyl ester (PC₇₀BM) are reported. Such ultra-low dark currents are realized through the enrichment of the hole selective p-type organic semiconductor near the anode contact. The resulting detectors demonstrate broadband X-ray response including an exceptionally high sensitivity of ≈1.5 mC Gy⁻¹ cm⁻² and <6% variation in angular dependence response under 6 MV hard X-rays. The above characteristics in combination with excellent dose linearity, dose rate linearity, and reproducibility over a broad energy range enable these detectors to be developed for medical and industrial applications.     

CVD金刚石薄膜的表面形貌研究

本工作采用HFCVD方法在Si、Mo衬底上生长出不同晶粒形貌的多晶金刚石薄膜,研究了生长条件(衬底温度、碳源浓度、反应压强)对金刚石薄膜晶粒形貌的影响。结果表明,在HFCVD方法中,金刚石薄膜晶粒形貌对生长条件十分敏感,生长条件的变化会导致不同形貌晶粒的生长。     

Self-Healing Cs3Bi2Br3I6 Perovskite Wafers for X-Ray Detection

Self-healing of defects imposed by external stimuli such as high energy radiation is a possibility to sustain the operational lifetime of electronic devices such as radiation detectors. Cs₃Bi₂Br₃I₆ polycrystalline wafers are introduced here as novel X-ray detector material, which not only guarantees a high X-ray stopping power due to its composition with elements with high atomic numbers, but also outperforms other Bi-based semiconductors in respect to detector parameters such as detection limit, transient behavior, or dark current. The polycrystalline wafers represent a size scalable technology suitable for future integration in imager devices for medical applications. Most astonishingly, aging of these wafer-based devices results in an overall improvement of the detector performance—dark currents are reduced, photocurrents are increased, and one of the most problematic properties of X-ray detectors, the base line drift is reduced by orders of magnitude. These aging induced improvements indicate self-healing effects which are shown to result from recrystallization. Optimized synthetic conditions also improve the as prepared X-ray detectors; however, the aged device outperforms all others. Thus, self-healing acts in Cs₃Bi₂Br₃I₆ as an optimization tool, which is certainly not restricted to this single compound, it is expected to be beneficial also for many further polycrystalline ionic semiconductors.     

硫掺杂纳米金刚石薄膜的图形化生长

利用电子增强热丝化学气相沉积(EACVD)技术,以CH4/H2/H2S/Ar为工作气体,SiO2/Si为衬底,制备了硫掺杂金刚石薄膜。研究了利用光刻技术实现薄膜的图形化生长。结果表明:以SiO2作掩模的光刻技术能够使得硫掺杂金刚石薄膜在光滑SiO2/Si基片上很好地图形化生长。Hall效应检测表明硫掺杂金刚石薄膜为n型,给出了n型金刚石/p-Si异质结的反向I-V特性曲线。     

Doping-spike PtSi Schottky infrared detectors with extended cutoffwavelengths

A technique incorporating a p⁺ doping spike at the silicide/Si interface to reduce the effective Schottky barrier of the silicide infrared detectors and thus extend the cutoff wavelength has been developed. In contrast to previous approaches which relied on the tunneling effect, this approach utilizes a thinner doping spike (<2 nm) to take advantage of the strong Schottky image force near the silicide/Si interface and thus avoid the tunneling effect. The critical thickness, i.e., the maximum spike thickness without the tunneling effect has been determined and the extended cutoff wavelengths have been observed for the doping-spike PtSi Schottky infrared detectors. Thermionic-emission-limited and thermally assisted tunneling dark current characteristics were observed for detectors with spikes thinner and thicker than the critical thickness, respectively     

Al薄膜对(002)ZnO/Al/Si结构基片中ZnO薄膜特性影响的实验研究

采用射频磁控溅射法沉积制备了(002)ZnO/A l/Si复合结构。研究了Al薄膜对(002) ZnO/Al/Si复合结构的声表面波器件(SAWD)基片性能影响以及当ZnO 薄膜厚度一定时的Al膜最佳厚度。采用X射线衍射(XRD)对Al和ZnO薄膜进行了结构表征 ,采用 扫描电镜(SEM)对ZnO薄膜进行表面形貌表征,并从薄膜生长机理角度进行了分析。结果 表明,加Al薄膜有利于ZnO薄膜按(002)择优取向生长,并且ZnO 薄膜的结晶性能提高;与(002)ZnO/Si结构基片相比,当Al薄膜 厚为100nm时,(002)ZnO/Al/Si结构中ZnO薄 膜的机电耦合系数提高 了65%。     

抛光工艺对硅基Pb_(1-x)Ge_xTe薄膜性能的影响

研究了不同的抛光方法(机械抛光、化学腐蚀及化学机械抛光)对硅基板上沉积的Pb_(1-x)Ge_xTe薄膜性能的影响.研究表明,经化学机械抛光(SiO_2胶体或Cr~+)的硅基板上所沉积的Pb_(1-x)Ge_xTe薄膜具有致密的结构及平直的界面,其沉积速率也比在化学腐蚀抛光表面的沉积速率大7%或18%(分别对应<111>和<100>晶向);薄膜具有明显高于化学腐蚀抛光基板沉积薄膜的折射率,且折射率随温度的降低而增加,而低温下折射率随波长的增加而增加;化学腐蚀抛光基板沉积薄膜的折射率的增加量明显大于化学机械抛光基板沉积薄膜的增加量;薄膜层经机械抛光后,其膜层结构、组分及其深度分布均未改变,但透射率增加,消光系数有所改善,折射率有所降低.     

The hetero-epitaxial SiCN/Si MSM photodetector for high-temperature deep-UV detecting applications

A visible-blind ultraviolet (UV) photodetector (PD) with metal-semiconductor-metal (MSM) structure has been developed on a cubic-crystalline SiCN film. The cubic-crystalline SiCN film was deposited on Si substrate with rapid thermal chemical vapor deposition (RTCVD). The optoelectron performances of the SiCN-MSM PD have been examined by the measurement of photo and dark currents and the currents' ratio under various operating temperatures. The current ratio for 254-nm UV light of the detector is about 6.5 at room temperature and 2.3 at 200/spl deg/C, respectively. The results are better than the counterpart /spl beta/-SiC of 5.4 at room temperature, and less than 2 for above 100/spl deg/C, thus offering potential applications for low-cost and high-temperature UV detection.     

平面型InGaAs红外探测器I-V特性研究

采用闭管扩散方式,利用SiO2及Si3N4扩散掩膜在NIN型InP/In0.53Ga0.47As/InP外延材料上制备了两种不同的平面型InGaAs红外探测器,研究了室温下不同扩散区面积的两种器件的正向I-V特性及反向暗电流密度与器件周长面积比的关系,结果表明,扩散区边缘的钝化是平面型InGaAs探测器的制备过程中非常重要的一环,而且Si3N4薄膜的钝化效果优于SiO2薄膜。室温下和-0.1V偏压下,采用Si3N4扩散掩膜的器件的暗电流密度约为20nA/cm2。