硅光电二极管激光损伤阈值随激光脉宽的变化

 对飞秒激光辐照下硅光电二极管损伤阈值进行了实验测量，对从1s到60fs不同脉宽激光辐照下硅光电二极管损伤阈值进行了讨论。实验数据表明，在1s到10ns脉宽范围内损伤所需能量密度近似而非严格地与脉宽的平方根成正比。信号分析表明硅光电二极管的损伤主要由热效应造成，而60fs激光辐照下的损伤阈值为0.1J/cm2，明显偏离普通温度分布预言的趋势。     

表面微构造的硅材料--一种新型的光电功能材料

在SF6气体氛围内用飞秒激光照射硅表面,可在硅表面产生准规则排列的微米量级尖峰结构,形成“黑硅”新材料．初步研究表明,这种“黑硅”新材料对波长为250-2500nm的光波有大于90％的吸收,同时它还具有相当好的场致发射特性．由于具有这些奇特的光电性质,这种表面微构造的硅材料在光电探测器、太阳能电池、平板显示器等器件制造领域有着重要的潜在应用价值．     

飞秒激光烧蚀硅表面产生微纳结构过程中激光脉冲数目的影响

为了研究飞秒激光脉冲数目与硅表面形貌之间的关系,在相同的SF6气体氛围下,改变照射硅表面的飞秒激光脉冲数,发现在飞秒激光照射下由硅表面形成的微型锥状尖峰的高度与飞秒激光脉冲数呈现一种非线性关系.通过对该关系的研究有利于找出在制造具有较高吸收效率的高微型锥状尖峰的"黑硅"的实验条件,有利于基于"黑硅"材料的光电器件转化效...     

基于PBDT-TT-F∶PCBM体异质结红光探测器的光电特性

采用旋涂工艺与蒸镀工艺结合的方法制备了PBDT-TT-F∶PCBM体异质结红光探测器,研究了活性层的混合比例和厚度、退火温度等因素对器件光电特性的影响。实验结果表明:活性层PBDT-TT-F∶PCBM的混合质量比为1∶1.5、厚度为150 nm、退火温度为100℃、时间为15 min时制备的器件性能最佳,在波长为650nm、功率为6.6 m W/cm~2的光照下,探测器光电流密度可达到0.85 m A/cm~2,光响应度达到128 m A/W。     

毫秒脉冲激光致硅光电二极管电学损伤的有限元分析及实验研究

为了研究毫秒脉冲激光致硅基PIN光电二极管电学损伤,基于热传导及弹塑性力学理论,在光电二极管内部材料各向同性并且P-I-N三层结构之间满足温度连续和热流平衡条件下,建立毫秒脉冲激光辐照硅基PIN光电二极管二维轴对称模型,采用有限元方法模拟分析了1064 nm Nd:YAG毫秒量级脉冲激光辐照硅基PIN光电二极管的温度场与应力场分布,并实验测量了硅基PIN光电二极管实验前后的电学参数.结果表明,激光辐照硅基PIN光电二极管时,温升使材料表面熔融、烧蚀,并且在空间上存在温度梯度变化,即激光辐照产生的热与应力使光敏面及硅晶格晶键损伤,最终造成光电探测器的探测性能下降.研究结果可为毫秒脉冲激光辐照硅基PIN光电二极管电学损伤机理奠定基础.     

基于标准CMOS工艺的UV/blue光电探测器

基于UMC 0.18μm CMOS工艺,提出一种适合紫外/蓝光探测的探测器,该器件由栅体互联的NMOS晶体管和横向/纵向光电二极管构成.其中,浅结的光电二极管由UMC工艺中Twell层(浅P阱)和Nwell层形成,以增强其对紫外/蓝光的吸收,栅体互联的NMOS晶体管可以放大光电流,提高探测器的灵敏度和动态范围.仿真结果表明,本文设计的紫外/蓝光探测器具有低的工作电压和暗电流,对300~550nm波长范围的光具有高的响应度和宽的动态范围.在弱光条件下(光强小于1μW/cm2),响应度优于105 A/W,随着光强增大,响应度逐渐降低,但总体仍超过103 A/W.     

SiCGe/SiC 异质结及其光电特性的MEDICI 模拟

在对SiC1-xGex三元合金主要特性的研究基础上，利用器件仿真器MEDICI模拟和分析SiCGe/SiC异质结光电二极管的光电特性。计算表明， SiC1-xGex 在Ge组分为0.3时与3C-SiC晶格失配较小，此时的SiCGe/SiC异质结对可见光和近红外光有较好的光谱响应。当P型SiC1-xGex层杂质浓度为1×1015cm-3、厚度1.6μm、x=0.3时，SiC1-xGex /SiC异质结光电二极管对0.52μm可见光有250mA/W左右的响应度，对0.7μm近红外光也有102mA/W左右的响应度。     

硅光电二极管的双光子响应

报道用连续光1.3μmInGaAsP半导体激光器探测硅光电二极管中的双光子响应(我们把倍频效应和双光子吸收统称为双光子响应).通过实验,证明在硅光电二极管中必然有倍频吸收引起的光电流存在.     

超快激光的光电应用

超快激光一般是指脉冲宽度短于10ps的脉冲激光,主要指短皮秒和飞秒(10-15s)激光。这个时间尺度短于激发态电子向晶格弛豫能量的所需时长,使光与物质相互作用呈现了与通常光激发显著不同的特性,也促成了其崭新的光电应用。围绕飞秒激光与物质相互作用快(作用时间短)、强(瞬态功率高)、精(非线性使作用区体积小,用作加工分辨率高)的特点,开展了系列研究,包括飞秒激光超快光谱用于光/电-电/光转换动力学探索,激光诱导气体成丝用于近程遥感探测,及飞秒激光微纳加工用于新原理、新材料微纳集成器件的制备。介绍了相关研究的进展。     

高速硅光电二极管的参数最佳化

在许多不同应用中所使用的高速硅光电二极管,要每个管子成功地运行,都有它自己的要求。宽带信息传输的光纤通讯是应用的一个领域,另外一些应用领域包括激光扫描传真系统,激光诊断和激光目标指示系统。这些光电二极管可用来探测450～1100毫微米的任何快速光脉冲。要有效地使用高速硅光电二极管,需要很好地掌握它的特性,以便使运转参数最佳化。让我们一个个地研究其中的一些参数并分析它们对光信号接收的影响。最后,把这些分析通过一些典型情况下的数字实例用于实践。     

Visible and near-infrared responsivity of femtosecond-laser microstructured silicon photodiodes

We investigated the current-voltage characteristics and responsivity of photodiodes fabricated with silicon that was microstructured by use of femtosecond-laser pulses in a sulfur-containing atmosphere. The photodiodes that we fabricated have a broad spectral response ranging from the visible to the near infrared (400-1600 nm). The responsivity depends on substrate doping, microstructuring fluence, and annealing temperature. We obtained room-temperature responsivities as high as 100 A/W at 1064 nm, 2 orders of magnitude higher than for standard silicon photodiodes. For wavelengths below the bandgap we obtained responsivities as high as 50 mA/W at 1330 nm and 35 mA/W at 1550 nm.     

Si-based near infrared photodetectors operating at 10 Gbit/s

We report on fast p-i-n near infrared photodetectors in pure germanium on silicon. The diodes were fabricated by chemical vapor deposition at 600 °C followed by thermal annealing at 900 °C. We also verified that bypassing the thermal treatment did not have significant effects on the resulting crystal quality, allowing to considerably reducing the thermal budget hence simplify the integration with silicon. We demonstrate the operation of photodiodes with responsivities of 0.4 and 0.2 A/W at 1.3 and 1.55 μm, respectively, as well as open-eye diagrams at 10 Gbit/s.     

Photocurrent properties of high—sensitivity GaN ultraviolet photodetectors

GaN epilayers were grown on sapphire substrates by metal-organic chemical vapour deposition. Metal－semiconductor－metal photoconductive detectors were fabricated using this material. The photocurrent properties of the detectors were measured and analysed. The spectrum response shows a high sensitivity in the wavelength region from 330 to 360nm, with a peak at 358nm and a sharp cutoff near 360nm. The maximum responsivities at 358nm were 700A/W (2V) and 7000A/W (30V). The relationship between responsivity and bias indicates that the responsivity increases linearly with bias until 30V. The influence of the spacing between two electrodes on the detector responsivity was also studied.     

InGaN/GaN p-i-n Photodiodes Fabricated with Mg-Doped p-InGaN Layer

Mg-doped p-InGaN layers with In composition of about 10% are grown by metalorganic chemical vapor deposition (MOCVD). The effect of the annealing temperature on the p-type behavior of Mg-doped InGaN is studied. It is found that the hole concentration in p-InGaN increases with a rising annealing temperature in the range of 600-850°C, while the hole mobility remains nearly unchanged until the annealing temperature increases up to 750°C, after which it decreases. On the basis of conductive p-type InGaN growth, the p-In_0.1Ga_0.9N/i-In_0.1Ga_0.9N/n-GaN junction structure is grown and fabricated into photodiodes. The spectral responsivity of the InGaN/GaN p-i-n photodiodes shows that the peak responsivity at zero bias is in the wavelength range 350-400nm.     

Waveguide-integrated telecom-wavelength photodiode in deposited silicon

We demonstrate photodiodes in deposited polycrystalline silicon at 1550 nm wavelength with 0.15 A/W responsivity, 40 nA dark current, and gigahertz time response. Subband absorption is mediated by defects that are naturally present in the polycrystalline material structure. The material exhibits a moderate absorption coefficient of 6 dB/cm, which allows the same microring resonator device to act as both a demultiplexing filter and a photodetector. We discuss the use of deposited silicon-based complementary metal-oxide semiconductor materials for nanophotonic interconnects.     

Normal incidence p-i-n Ge heterojunction photodiodes on Si substrate grown by ultrahigh vacuum chemical vapor deposition

We report on normal incidence p-i-n heterojunction photodiodes operating in the near-infrared region and realized in pure germanium on planar silicon substrate. The diodes were fabricated by ultrahigh vacuum chemical vapor deposition at 600 °C without thermal annealing and allowing the integration with standard silicon processes. Due to the 0.14% residual tensile strain generated by the thermal expansion mismatch between Ge and Si, an efficiency enhancement of nearly 3-fold at 1.55 μm and the absorption edge shifting to longer wavelength of about 40 nm are achieved in the epitaxial Ge films. The diode with a responsivity of 0.23 A/W at 1.55 μm wavelength and a bulk dark current density of 10 mA/cm² is demonstrated. These diodes with high performances and full compatibility with the CMOS processes enable monolithically integrating microphotonics and microelectronics on the same chip.     

MMW detection by superconducting films-applications of high temperature superconducting films

Conclusions Superconductors exhibit two basic modes of radiation detection —a thermal or bolometer mode and a rectification mode which depends on a nonlinear voltage-current characteristic. The SIS detector has been shown to have a quantum limited current responsivity of e/hf. By analogy, weak link detectors may have a quantum limited voltage responsivity of about 2eR/hf. Granular films behave like arrays of weak links.Both thermal and rectification modes have been observed in HTOS films. They can be characterized by the dependence of film resistance on temperature and current. Analysis of the temperature dependence of film resistance indicates that bolometer responsivities are limited by the broader resistive transition observed in HTOS films. HTOS films show a strong nonlinear dependence of resistance on current at lower temperatures. In this region, we expect voltage responsivities greater than 1 KV/W. This is a very promising mode for detection and mixing of far infrared and millimeter waves.     

用激光微细加工制作平面型InGaAs/InP PIN 光探测器

 采用激光微细加工技术来制作单片集成光接收机的探测器，在制作过程中，用固态杂质源10.6 μm激光诱导Zn扩散工艺来进行探测器的p-区掺杂。制作出平面型顶部入射的InGaAs/InP PIN 光探测器，响应度为0.21 A/W。分析了激光诱导扩散中影响探测器性能的因素，因此提出了扩散温度自动控制、扩散区温度分布均匀化及激光焦斑与扩散区精确对准等相应的改进方法。     

Properties of Schottky barrier photodiodes based on InGaN/GaN MQW structures

The characterization and fabrication of Schottky barrier photodiodes based on InGaN/GaN multiple-quantum well structures in the active region are presented. These devices allow photodetection based on nitrides from the visible (VIS) to the ultraviolet (UV) ranges to be covered, and offer an alternative to InGaN bulk devices. Indium concentrations in the 8 to 14% range have been used. It has also been shown that in these devices the envelope average electric field in the depletion region can be tailored as a result of the huge polarization fields present in wells and barriers. As a consequence, two different device operation modes, as a function of voltage bias, are possible. By proper well and barrier design, charge accumulation can be produced at the boundaries of the active region and a large responsivity for photons with energies close to the barrier bandgap is found. Photodetectors show a rather sharp detection edge with a contrast of more than four orders of magnitude, reaching peak responsivities in the 0.1–1.0 A/W range. Self-consistent simulations and a discussion on the electric fields in the active regions are also presented.     

Array of concentric CMOS photodiodes for detection and de-multiplexing of spatially modulated optical channels

A novel octagonal structure of photodiodes using standard CMOS technology has been developed to serve as a de-multiplexer for spatially multiplexed fiber optic communication systems. Concentric photodiodes of six different structure types are investigated for this purpose. The responsivity of the fabricated devices lies within ten percent of the theoretical values at 660 nm. The concept is demonstrated for silicon and the geometry can be extended to other materials commonly used in optical communications. This presents structural details, device model and equivalent circuits for these devices. Test results for detector responsivity, leakage currents and quantum efficiency are also presented.