表面微结构的高响应度Si基近红外光电探测器

为了使Si基光电探测器应用到近红外光波段,需要提升其对光的响应度。通过等离子体光刻在硅基光电探测器表面制备规则有序的微结构阵列,另外通过原子层沉积(ALD)在微结构表面生长一层Al_2O_3膜,研究它的抗反射和钝化作用。对比测量器件的表面反射率和I-V特性曲线,并计算器件在808 nm近红外光下的光响应度。通过计算发现器件的响应度由最初的0.063 A/W提高到0.83 A/W。     

A novel high-speed silicon MSM photodetector operating at 830 nmwavelength

A novel high-speed silicon photodetector that operates at a wavelength of 830 nm is reported. It consists of a Metal-Semiconductor-Metal (MSM) detector that is fabricated on a 5-μm thick silicon membrane. The detector has a measured -3 dB bandwidth of 3 GHz at 10 V, which is almost one order of magnitude larger than the reported bandwidth of conventional silicon MSM detectors as measured at 830 nm. The DC responsivity is 0.17 A/W, corresponding to an internal quantum efficiency of 60.5% and an external quantum efficiency of 25.4%. The large bandwidth and good responsivity at the wavelength of interest, combined with its low operating voltage and compatibility with most silicon integrated circuit technologies, make this detector a promising candidate for monolithic optoelectronic receiver circuits for use in short distance optical communication systems and computer interconnects     

Waveguide integrated MSM photodetector on InP

An interdigitated metal-semiconductor-metal Schottky barrier photodetector monolithically integrated with a ridge waveguide and suitable for the 1.3-1.6 μm wavelength range is reported. The GaInAs detector on top of a GaInAsP (Λ_g=1.2 μm) guide used a 35 nm layer of GaAs to enhance the Schottky barrier. Internal quantum efficiencies of around 80% and a pulse response of 147 ps (FWHM) were obtained     

AlGaN MSM结构日盲型紫外探测器

采用低压-金属有机化学气相沉积(MOCVD)法在(0001)方向的AlN/蓝宝石模板上生长得到Al组分为40%的AlGaN材料,设计并制作了MSM型AlGaN日盲紫外探测器。通过HRXRD,SEM,AFM对AlGaN材料进行了表征,结果表明:该材料为六方相结构,且应变程度很小,粗糙度(RMS)为1.32 nm。通过测试器件在230³20 nm之间、在不同偏压下的光谱响应曲线,发现器件的截止波长在285 nm附近,截止边很陡峭;器件的峰值响应波长为275 nm;在7 V偏压下,器件峰值响应度达到最大2.8 mA/W;零偏压下,器件的暗电流1×10-13A,器件的暗电流很小。     

High infrared responsivity Indium-doped silicon detector material compensated by neutron transmutation

The use of the neutron transmutation for producing precisely compensated, extrinsic idium-doped, silicon detector material of high infrared responsivity is reported. Highly indium-doped silicon crystals containing (1 to 3) × 10¹⁷cm^-3indium concentrations and residual acceptors in the low 10¹²cm^-3have been grown by float-zone doping. The high purity obtained by this growth technique enables very low net donor compensation densities to be achieved by neutron irradiation in a reactor. Transmuted phosphorus concentrations ranging from (1 to 20) × 10¹²cm^-3have been investigated and compensation densities,N_{D} - N_{A}, as low as 2 × 10¹²cm^-3have been achieved in irradiated samples after suitable damage annealing. Residual radioactivity due to transmuted indium isotopes approaches negligibly low levels for the neutron fluences required with high purity float-zone Si:In material. Significant improvements in infrared detector performance have been demonstrated with neutron compensated indium-doped silicon. Peak responsivities up to 100 A/W at 50 K and 10³-V/cm detector bias have been measured, corresponding to dc photoconductive gains in the 30 to 40 range and mobility-lifetime products > 10^-3cm²/V. Additional studies indicate that the detector responsivity, which is adversely affected by high-temperature CCD fabrication processes, can be restored significantly by phosphorus gettering techniques.     

Ultralow dark current GaAlAs/GaAs MSM photodetector

An interdigitated GaAlAs/GaAs metal-semiconductor-metal photodetector designed to be fully integrable with HIGFET-based digital integrated circuits and which exhibit a dark current as low as 100 pA at 10 V bias voltage is presented. Static and dynamic responsivities are reported, as well as noise properties. Photocurrents (for bias voltage higher than 4 V) comparable to those measured with a pin photodiode, and a shot noise cutoff frequency in excess of 13 GHz were recorded.<>     

Modeling of InGaAs MSM photodetector for circuit-level simulation

An accurate model for In_0.53Ga_0.47As metal-semiconductor-metal (MSM) photodetectors is presented for circuit-level simulation. Dark and dc current characteristics are investigated and modeled. To accurately simulate the large-signal response of MSM photodetectors, impulse response functions and convolution integrals are implemented into SPICE. The transit-time limitation is also incorporated into the small-signal analysis. Most circuit parameters preserve the physical meaning. S-parameter measurements are used to find the circuit parameters critical to transient and ac analyses. Results are compared with experimentally obtained data, and excellent agreement is obtained consistently on InGaAs photodetectors of different sizes     

A high gain silicon photodetector

High gain silicon photodetectors were designed and fabricated using a sandwich structure of gold compensated n-type material. Steady-state photoconductive current gains as high as 26 were measured, while transient peak gains of 50 were attained. The measured response time varied from 10^-6to 2×10^-7sec, depending inversely upon the incident light intensity. The electron lifetimes were calculated using the existing capture cross-section data of the gold recombination centers. These results are in good agreement with the estimated electron lifetime based upon the measured photoconductive current gain and the calculated transit time values. The detectivity of some of the devices was typically D^*(λp, 900, 1) =9.5×10⁹cm (c/s)^1/2/watt and the noise equivalent power NEP = 1.6×10^-11watts/(c/s)^1/2.     

An AlGaAs-GaAs-based RCE MSM photodetector with delta modulation doping

An AlGaAs-GaAs-based resonant-cavity-enhanced, heterostructure metal-semiconductor-metal photodetector with delta modulation doping operating at 850 nm is reported. Delta doping of the top AlGaAs layer produces a confined electron cloud and an associated electric field. Photocurrent spectral response shows the delta-doped photodetector has larger spectral response than the undoped one at all wavelengths. The delta-doped device also shows lower dark current and higher photo response compared to an undoped one, resulting in over an order of magnitude increase in its dynamic range. Time responses indicate that the doped devices have larger amplitudes but smaller full-width at half-maximum (FWHM) than the undoped ones. The increase in responsivity and speed of response is attributed to the vertical electric field and suitable potential profile in the direction of growth, while the decrease of the dark current is due to the confined electron cloud.     

金属-半导体-金属(MSM)结构4H-SiC紫外光电探测器的研制

MSM结构探测器具有结构与工艺简单、制备成本低、量子效率高等特点而在探测器应用中得到重视。本文制备了采用镍作为肖特基接触形成的MSM4H—SiC紫外光电探测器，并测量和分析了在不同的偏压下其光电特性。结果表明，该探测器的暗电流非常小，在偏压为15V的时候，漏电流密度约为70nA／cm^2，光电流比暗电流高约2个数量级，其光谱响应表明，其最高光谱响应与380nm的比值约为1000倍，说明该探测器具有良好的紫外可见比。     

An ultraviolet MSM photodetector with electrically tunable spectral sensitivity

Ultraviolet photodetectors based on interdigital Schottky-barrier contacts to a ZnCdS/GaP heterostructure, which have low dark currents, are fabricated and investigated. It is found that the characteristics of the spectral response of these detectors depend on the bias and the long-wavelength boundary of the response of a ZnCdS/GaP metal-semiconductor-metal (MSM) diode can be shifted from 355 nm to 440 nm as the bias varies from 40 to 80 V. It is found that, at the wavelength of the maximum photosensitivity (355 nm), the ampere-watt sensitivity of the detector is 0.1 A/W.     

Effect of dimensional parameters on the current of MSM photodetector

In this work, we present the influence of dimensional parameters on dark current and photocurrent of the metal-semiconductor-metal photodetector (MSM). MSM photodetectors of different sizes have been fabricated on GaAs (NID). The active area of MSM samples varies between 1×1 μm² and 10×10 μm² with equal electrodes spacing and finger widths (l=D) varying between 0.2 and 1 μm. The I(V) characterization in inverse and direct polarization in darkness shows good symmetry of curves, which shows the good performance of components and successful fulfillment of the Schottky contacts. The application of laser fiber of incident light power of 16 mW at wavelength of 850 nm for the illumination of the MSM photodetectors showed the evolution of the photocurrent ranging from 0.75 to 1.81 mA, respectively, for 1 to 0.2 μm electrodes spacing at 3 V and active area S=3×3 μm². We showed also that variation ranging from 0.45 to 2.5 mA, respectively, for S=1×1 μm² to S=10×10 μm² at 3 V and 0.3 μm electrodes spacing. The resistance of MSM photodetectors obtained evolved proportionally to the electrodes spacing (0.87 kΩ for D=0.2 μm and 2.27 kΩ for D=1 μm with S=3×3 μm²) and inversely proportional to the surface area (2.02 kΩ for S=1×1 μm², and 0.56 kΩ for S=10×10 μm² with 0.3 μm inter electrodes spacing).     

Optical signal distribution to MSM photodetector arrays viaintegrated polyimide waveguides

The integration of metal-semiconductor-metal (MSM) photodetector arrays with polyimide ridge waveguides is demonstrated. MSM detectors were fabricated using transparent indium tin oxide (ITO) interdigitated electrodes on semi-insulating GaAs substrates. An optical buffer layer of SiO₂ was deposited and patterned, and then polyimide ridge waveguides were fabricated on top by spin coating and photolithography. The guides were multimode with widths from 10 to 50 μm. Light at 830 nm was coupled efficiently from the waveguides through gaps in the SiO ₂ buffer layer into the underlying detector structures. Absolute responsivities of the integrated MSM devices were around 0.5 A/W and the 3 dB bandwidths of 5-6 GHz were measured. Division of the input signal between sets of two and four detectors under a single waveguide has been achieved, highlighting the potential for the fabrication of integrated optoelectronic switches     

Reducing dark current in a high-speed Si-based interdigitated trench-electrode MSM photodetector

The authors have studied higher dark-current temperature dependence in a trench-electrode Si-based metal-semiconductor-metal (MSM) photodetector which has a hydrogenated intrinsic amorphous silicon (i-a-Si:H) dark-current suppression layer. The poor dark-current temperature-dependence performance could be improved significantly by reducing the number of trap states in the depletion region of the reverse-biased crystalline/amorphous Si heterojunction. To reduce the trap states, a modified plasma-enhanced chemical vapor deposition (PECVD) system, which reduced the ion bombardment on the Si substrate, was employed to deposit an i-a-Si:H layer. Moreover, since fewer trap states in a photodetector will result in a degradation of the fall time of the temporal response of the device, a Ti electrode, which has a lower Schottky barrier height (0.62 eV) than that (0.84 eV) of the previous Cr electrode used with i-a-Si:H, was employed for compensation. The device obtained exhibited very good dark-current stability and temporal response. The dark current only increased from 6 to 34 nA, when the operating temperature was increased from room temperature (R. T.) to 57/spl deg/C, much lower than that of the previously reported 3-V bias voltage one (from 22 to 209 nA). Device responsivity and quantum efficiency also showed obvious improvement, both at R. T. (0.192 A/W and 0.29) and 57/spl deg/C (0.213 A/W and 0.32, respectively) and were higher than those previously reported (0.174 A/W and 0.26, at 57/spl deg/C).     

1.3 mu m InGaAs MSM photodetector with abrupt InGaAs/AlInAs interface

The authors have fabricated long-wavelength abrupt-junction InGaAs/AlInAs metal-semiconductor-metal photodetectors that are potentially compatible with AlInAs/InGaAs H-MESFETs. The detectors have nanoampere dark currents and low capacitance. The responsivity at 10 MHz is 0.32 A/W, corresponding to at least 90% internal collection efficiency. The device performance limitations due to charge storage at the InGaAs/AlInAs interface are discussed, and it is shown that despite charge pile up, high data rates (>3 GHz) have been achieved at low bias voltages, provided the incident intensity is low.<>     

Performance of a near-infrared GaAs metal-semiconductor-metal (MSM)photodetector with islands

A GaAs metal-semiconductor-metal (MSM) photodetector with ultrasmall gold islands deposited on its photosensitive surface is described. The interdigitated detector is fabricated on a semi-insulating substrate in a MESFET-compatible technology. Responsivity as high as 1.8 A/W is obtained at 0.86 μm and a bias voltage of 8 V. This represents over a sixfold increase with respect to responsivity of a conventional MSM photodetector. The mechanism for dark current is suggested and breakdown characteristics are presented     

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.     

A high-speed, high-sensitivity silicon lateral trench photodetector

We report a novel silicon lateral trench photodetector that decouples the carrier transit distance from the light absorption depth, enabling both high speed and high responsivity. The photodetector, fabricated with fully VLSI compatible processes, exhibits a 6-dB bandwidth of 1.5 GHz at 3.0 V and an external quantum efficiency of 68% at 845 nm wavelength. A photoreceiver with a wire-bonded lateral trench detector and a BiCMOS transimpedance amplifier demonstrates excellent operation at 2.5 Gb/s data rate and 845 nm wavelength with only a 3.3 V bias     

A VLSI-compatible high-speed silicon photodetector for optical datalink applications

A novel silicon photodetector suitable for high-speed, low-voltage operation at 780- to 850-nm wavelengths is reported. It consists of an interdigitated p-i-n detector fabricated on a silicon-on-insulator (SOI) substrate by using a standard bipolar process. Biased at 3.5 V, this device attains a -3-dB bandwidth in excess of 1 GHz at λ=840 nm. The dc responsivity measured at λ=840 nm on nonoptimized structures ranges from 0.05 to 0.09 A/W, depending on the finger shadowing factor. A new approach for improving the responsivity is proposed and quantitatively analyzed. The fabricated devices exhibit extremely low dark currents, small capacitance, large dynamic range, and no evidence of low-frequency gain. The overall performance and process compatibility of these photodetectors make them viable candidates for the fabrication of silicon monolithic receivers for fiber-optic data links     

基于金属-半导体-金属结构的Bi2Te3室温高响应率太赫兹探测器

基于二维拓扑绝缘体Bi_2Te_3材料利用微纳工艺制备了金属-拓扑绝缘体-金属(MTM)结构的太赫兹光电探测器.器件在0. 022 THz的响应率可达2×10~3A/W,噪声等效功率(NEP)低于7. 5×10~(-15)W/Hz~(1/2),探测率D~*高于1.62×10~(11)cm·Hz~(1/2)/W;在0. 166 THz的响应率可达281. 6 A/W,NEP低于5. 18×10~(-14)W/Hz~(1/2),D~*高于2. 2×10~(10)cm·Hz~(1/2)/W;在0. 332 THz的响应率可达7. 74 A/W,NEP低于1. 75×10~(-12)W/Hz~(1/2),D~*高于6. 7×10~8cm·Hz~(1/2)/W;同时器件在太赫兹波段具有小的时间常数(7～8μs).该项工作突破了传统光子探测的带间跃迁,实现了可室温工作、高响应率、高速响应以及高灵敏度的太赫兹探测器件.