A normal amorphous silicon-based separate absorption andmultiplication avalanche photodiode (SAMAPD) with very high optical gain

A normal amorphous silicon-based separate absorption and multiplication avalanche photodiode (SAMAPD) with very high optical gain of the avalanche photodiode has been developed successfully by plasma-enhanced chemical vapor deposition (PECVD). Based on experimental results, using undoped α-Si:H as avalanche layer material and α-Si_1-xGe_x:H as absorption layer material, the hole-injection (HI) type SAMAPD yields a very high optical gain of 686 at a reverse bias of 16 V under an incident light power of P_in =1 μW and has a rise time of 145 μs at a load resistance R=10 kΩ. Thus the amorphous silicon-based SAMAPD is a good candidate for the long-range optical communication applications     

Modulator driver and photoreceiver for 20 Gb/s optic-fiber links

Two integrated circuits, a modulator driver and a photoreceiver integrating a metal-semiconductor-metal (MSM) photodetector, a differential transimpedance amplifier and two limiting amplifier stages for high-speed optical-fiber links are presented. The IC's were manufactured in a 0.2 μm gate-length AlGaAs-GaAs high-electron mobility transistor (HEMT) technology with a f_T of 60 GHz. The modulator driver IC operates up to 25 Gb/s with an output voltage swing of 3.3 V_p-p at each output. The 1.3-1.55 μm wavelength monolithically integrated photoreceiver optoelectronic integrated circuit (OEIC) has a bandwidth of 17 GHz with a high transimpedance gain of 12 kΩ. Eye diagrams are demonstrated at 20 Gb/s with an output voltage of 1 V_p.p     

7.1 GHz bandwidth monolithically integratedIn0.53Ga0.47As/In0.52Al0.48As PIN-HBT transimpedance photoreceiver

A monolithically integrated photoreceiver using an InAlAs/InGaAs HBT-based transimpedance amplifier has been fabricated and characterized. The p-i-n photodiode is implemented using the base-collector junction of the HBT. The 5 μm×5 μm emitter area transistors have self-aligned base metal and non-alloyed Ti/Pt/Au contacts. Discrete transistors demonstrated f_T and f_max of 54 GHz and 51 GHz, respectively. The amplifier demonstrated a -3 dB transimpedance bandwidth of 10 GHz and a gain of 40 dBΩ. The integrated photoreceiver with a 10 μm×10 μm p-i-n photodiode showed a -3 dB bandwidth of 7.1 GHz     

Optical devices from AlGaAs-GaAs HBTs heavily doped with amphotericSi

A new optoelectronic multifunctional device, having triple function of light emission, detection and amplification have been developed and some preliminary integrated circuits are demonstrated. The devices consist of N-p-n or N-P-n AlGaAs-GaAs HBT utilizing amphoteric Si heavily-doped GaAs or AlGaAs p-type base layer. Maximum current gain of 3600, and light output power of about 0.17 μW with 100 μA base current (I_b) in transistor mode operation and of about 10 μW with I_b=40 mA in diode mode operation are obtained. The optical emission wavelengths in both are about 0.85-0.86 μm. Optical gain of about 130 was obtained near the 0.86 μm wavelength as a detection transistor. Spectrum matching between emission and detection wavelength range is achieved. Some monolithic integrated circuits constituted of the transistors are proposed and demonstrated successfully. The relationship between current gain and radiative quantum efficiency at the transistor operation is also discussed     

8-element linear array monolithic p-i-n MODFET photoreceivers usingmolecular beam epitaxial regrowth

An 8-element linear array of single-stage integrating front-end photoreceivers using molecular beam epitaxial (MBE) regrowth was investigated. Each element consisted of a p-i-n In_0.53Ga_0.47As photodiode integrated with a selectively regrown pseudomorphic In_0.65Ga_0.35As/In_0.52Al_0.48 As MODFET. Cutoff frequencies of 1.0-μm discrete regrown MODFETs were f_t=24 GHz and f_max=50 GHz. Transconductance of the regrown MODFETs was as high as 495 mS/mm with a current density (I_ds) of 250 mA/mm. The 3-dB bandwidth of the photoreceiver was measured to be 1 GHz. The bit rate sensitivity at 1 Gb/s was -31.8 dBm for BER 10^-9 using 1.55 μm excitation for a photoreceiver with an anti-reflection coating. The single-stage amplifier exhibited up to 25 dB flatband gain of the photocurrent, and a two-stage amplifier was up to 31 dB of gain. Good uniformity between each photoreceiver element in the array was achieved. Electrical crosstalk between photoreceiver elements was estimated to be ~-34 dB     

Monolithic PIN/preamplifier circuit integrated on a GaAs substrate

An AlGaAs/GaAs PIN photodiode and a GaAs transimpedance amplifier including six FETs have been monolithically integrated on a GaAs substrate. A photoreceiver operation exhibiting an excellent linearity has been demonstrated. The photodiode sensitivity of 0.44 A/W and the amplifier transimpedance of 1.0 × l04 V/A have been determined from the measurement.     

High-speed, highly sensitive OEIC using clocked vertical BJT'sphotoDarlington in CMOS technology

A novel CMOS synchronized photoreceiver is proposed for conversion of optical input pulses to digital output signals. The photoreceiver circuit consists of a photoDarlington used as a detector of input light followed by a current-mirror comparator used as a converter to electronic signals. A combination of two p-n-p vertical CMOS bipolar junction transistors controlled by an external clock is designed to achieve the first clocked photoDarlington structure. The generated photocurrent is amplified and digitized by the current-mirror comparator in a return to-zero format. The synchronized photoreceiver has been implemented in a standard digital 0.7 μm, 5 V n-well CMOS technology with an effective area of 100×60 μm². It was measured to operate at 100 MHz with an external input light of 13.3 fJ/pulse (-18.8 dBm/beam)     

Monolithically integrated multichannel SiGe/Si p-i-n-HBTphotoreceiver arrays

A low-power, short-wavelength eight-channel monolithically integrated photoreceiver array, based on SiGe/Si heterojunction bipolar transistors, is demonstrated. The photoreceiver consists of a photodiode, three-stage transimpedance amplifier, and passive elements for feedback, biasing and impedance matching. The photodiode and transistors are grown by molecular beam epitaxy in a single step. The p-i-n photodiode exhibits a responsivity of 0.3A/W and a bandwidth of 0.8 GHz at λ=0.88 μm. The three-stage transimpedance amplifier demonstrates a transimpedance gain of 43 dBΩ and a -3 dB bandwidth of 5.5 GHz. A single channel monolithically integrated photoreceiver consumes a power of 6 mW and demonstrates an optical bandwidth of 0.8 GHz. Eight-channel photoreceiver arrays are designed for massively parallel applications where low power dissipation and low crosstalk are required. The array is on a 250-μm pitch and can be easily scaled to much higher density. Large signal operation up to 1 Gb/s is achieved with crosstalk less than -26 dB. A scheme for time-to-space division multiplexing is proposed and demonstrated with the photoreceiver array     

InGaAsP channel HFET's on InP for OEIC applications

A model for the calculation of the input noise of a high impedance photoreceiver is proposed, taking into account the contributions of low-frequency characteristics of the FET. Simulations based on this approach show that excess gate leakage current and low-frequency excess noise, usually observed in InGaAs channel FET's, strongly penalize the photoreceiver sensitivity for low to medium data rates. New InGaAsP channel HFET's have been developed and fabricated to solve those problems, dc measurements on 1×100 μm² gate HFET's show good I_ds-V_ds characteristics with associated gate leakage currents lower than 200 nA. Promising ft of 18 GHz and f _max of 40 GHz have been recorded on 0.5×200 μm² gate transistors. Low-frequency gate and channel noise measurements demonstrate the suitability of InGaAsP channel HFET structure and technology for low noise applications. A hybrid pin-HFET high impedance photoreceiver has been assembled with a 1×150 μm ² gate transistor. A very close agreement is found between photoreceiver input noise predicted by our model and experimental results. Record sensitivities of 34.8 dBm at 622 Mbit/s and -28.7 dBm at 2.5 Gbit/s are inferred from noise measurements, confirming the strong potential of InGaAsP channel HFET's for the fabrication of high sensitivity photoreceivers operating at moderate data rates     

Effectiveness of the pseudowindow for edge-coupled InP-InGaAs-InPPIN photodiodes

We have shown that edge-coupled PIN photodiodes can benefit from the incorporation of a pseudowindow of appropriate thickness. In our experiments, a pseudowindow 2-3 μm thick can effectively protect the device and antireflection (AR) coating during the cleavage process without sacrificing the device efficiency and speed performance. Also, devices with a pseudowindow could have an increased coupling aperture, which results from the dielectric layers, and thus permits more light to enter the device. The light input facet of the device without a pseudowindow can be severely damaged during the cleavage process and AR coating, which may degrade the device dark current by several orders of magnitude. We also found that, even with partial recovery after rapid thermal annealing, devices without pseudowindows still suffer from damage and the maximum photocurrent is typically restricted to about 3 mA. The typical performance at -5 V of a device with a 100-μm junction length and a 3-μm pseudowindow is a responsivity of ~0.95 A/W responsivity and a ~5.5-GHz bandwidth at a wavelength of 1.3 μm under 100-μW illumination     

A monolithically integrated photoreceiver compatible withInP/InGaAs HBT fabrication process

We demonstrate, for the first time, the characteristics of an InP/InGaAs HBT-compatible pin-PD and a monolithically integrated pin/HBT photoreceiver. The pin-PD can produce a short pulse with an FWHM of 80.8 ps followed by an elongated tail, when illuminated by optical pulses with an FWHM of 40 ps and a wavelength of 1.3 μm. The fall time of the output is determined by the transit time of holes generated in the n ⁺-InGaAs layer. The monolithically integrated photoreceiver, consisting of the pin-PD and a transimpedance preamplifier, can operate at 2.5 Gb/s with a sensitivity of -9.8 dBm. This performance was mainly limited by the characteristics of the pin-PD     

High-Speed Low-Noise p-i-n InGaAs Photoreceiver at 2-$mu$ m Wavelength

A p-i-n InGaAs photoreceiver with a 3-dB bandwidth of 6 GHz at 2-mum wavelength is presented. The photodiode, having a responsivity of 1.34 A/W and a dark current of 400 nA, is coupled to a transimpedance amplifier to provide a conversion gain of 670 V/W at room temperature.     

Design, modeling, and characterization of monolithically integratedInP-based (1.55 μm) high-speed (24 Gb/s) p-i-n/HBT front-endphotoreceivers

High-speed, long-wavelength InAlAs/InGaAs OEIC photoreceivers based on a p-i-n/HBT shared layer integration scheme have been designed, fabricated and characterized. The p-i-n photodiodes, formed with the 6000 Å-thick InGaAs precollector layer of the HBT as the absorbing layer, exhibited a responsivity of ~0.4 A/W and a -3 dB optical bandwidth larger than 20 GHz at λ=1.55 μm. The fabricated three-stage transimpedance amplifier with a feedback resistor of 550 Ω demonstrated a transimpedance gain of 46 dBΩ and a -3 dB bandwidth of 20 GHz. The monolithically integrated photoreceiver with a 83 μm p-i-n photodiode consumed a small dc power of 35 mW and demonstrated a measured -3 dB optical bandwidth of 19.5 GHz, which is the highest reported to date for an InAlAs/InGaAs integrated front-end photoreceiver. The OEIC photoreceiver also has a measured input optical dynamic range of 20 dB. The performance of individual devices and integrated circuits was also investigated through detailed CAD-based analysis and characterization. Transient simulations, based on a HSPICE circuit model and previous measurements of eye diagrams for a NRZ 2³¹-1 pseudorandom binary sequence (PRBS), show that the OEIC photoreceiver is capable of operation up to 24 Gb/s     

Low threshold InGaAs/GaAs 45° folded cavity surface-emittinglaser grown on structured substrates

A novel folded cavity surface-emitting laser structure integrating a horizontal cavity InGaAs/GaAs laser grown on a structured substrate with a high reflectivity Bragg reflector has been fabricated. Devices with threshold currents of 8 mA and CW wall plug efficiencies at 5% at 6 mW output power have been demonstrated at a wavelength of 0.99 μm. By combining a cleaved uncoated mirror with the 45° deflecting mirror the authors have obtained threshold current as low as 5 mA for a device 450 μm long     

Development of an integrated high speed silicon PIN photodiodesensor

A silicon integrated PIN photodiode sensor, combined with a bipolar IC on same substrate (that is, a PIN photo integrated circuit sensor: PIN-PICS), was developed by employing a high resistive P^-- epitaxial layer on a P⁺ substrate for creating a high speed and high optical responsivity PIN photodiode. We fabricated this device based on two special techniques: (1) the PIN photodiode is formed on a P^--/P⁺ substrate structure and isolated from bipolar components by the combination of a P^--well and a trench isolation, and (2) bipolar components are formed by the doubly diffused buried layer of the P^--well and the N⁺ collector wall. All of these components, such as npn and pnp transistors, were arranged within the lightly doped P^--well regions. From several kinds of trial samples, the following results were obtained. The PIN photodiode with 0.145 mm² active area indicated 680 MHz for cutoff frequency at 10 V bias with 830 mn radiation. In the case of 20 V bias, this value exceeded 1.5 GHz. This PIN-PICS was applied to a 10 Mbit/s burst mode compatible optical monolithic receiver and a transimpedance amplifier, and it has shown the expected results     

CMOS silicon avalanche photodiodes for NIR light detection: a survey

This paper surveys recent research on CMOS silicon avalanche photodiodes (SiAPD) and presents the design of a SiAPD based photoreceiver dedicated to near-infrared spectroscopy (NIRS) application. Near-infrared spectroscopy provides an inexpensive, non-invasive, and portable means to image brain function, and is one of the most efficient diagnostic techniques of different neurological diseases. In NIRS system, brain tissue is penetrated by near-infrared (NIR) radiation and the reflected signal is captured by a photodiode. Since the reflected NIR signal has very low amplitude, SiAPD is a better choice than regular photodiode for NIR signal detection due to SiAPD`s ability to amplify the photo generated signal by avalanche multiplication. Design requirements of using CMOS SiAPDs for NIR light detection are discussed, and the challenges of fabricating SiAPDs using standard CMOS process are addressed. Performances of state-of-the-art CMOS SiAPDs with different device structures are summarized and compared. The efficacy of the proposed SiAPD based photoreceiver is confirmed by post layout simulation. Finally, the SiAPD and its associated circuits has been implemented in one chip using 0.35 μm standard CMOS technology for an integrated NIRS system.     

SOI基垂直入射Ge PIN光电探测器的研制

研制了在SOI衬底上工作于近红外波段的垂直入射GePIN光电探测器。采用低温Ge缓冲层技术,在超高真空化学气相淀积系统(UHV/CVD)上生长探测器材料。测试表明,器件的暗电流主要来源于表面漏电流,暗电流密度随着尺寸的增加而减小,在2V偏压时暗电流密度可达17.2mA/cm2;器件在波长1.31μm处的响应度高达0.22A/W,对应量子效率为20.8%。无偏压时,器件的响应光谱在1.2～1.6μm波长范围内观察到4个共振增强峰,分别位于1.25、1.35、1.45和1.55μm左右,峰值半高宽约为50nm,共振增强效应是由SOI衬底的高反射率引起的。采用传输矩阵法模拟的响应光谱与实验测量结果吻合良好。     

Hybrid integration of eight channel PD-array on silica-based PLCusing micro-mirror fabrication technique

A novel micro-mirror for vertical optical output has been successfully fabricated in a singlemode silica-based planar lightwave circuit (PLC) on Si. An eight channel planar photodiode array was assembled on this PLC. The assembled PLC exhibited an average responsivity of 0.92 A/W and a responsivity deviation of 0.34 dB at a wavelength of 1.31 μm     

Monolithic Photoreceiver Constructed With a ZnSe MSM Photodiode and an InGaP/GaAs HBT

The monolithic integration of a ZnSe metal–semiconductor–metal photodiode and an InGaP/GaAs heterojunction bipolar transistor has been achieved successfully on a GaAs substrate. As a result of a current amplification ratio of 20.8, the present monolithic photoreceiver illuminated at an optical input-power intensity of 10 $muhbox{W}$ has shown high voltage amplification sensitivity of $-hbox{29.6} hbox{mV}/muhbox{W}$. The fabrication process and characterization for the integrated device will be useful for the development of wide-bandgap-based short-wavelength optoelectronic integrated circuits in the future.      

Low-Noise Large-Area Quad Photoreceivers Based on Low-Capacitance Quad InGaAs Photodiodes

We report a large-area quad photoreceiver (2 times 2 array) having an equivalent input current noise density of <3.2 pA/radicHz per quadrant up to a 3-dB bandwidth of ~20 MHz. The low-noise photoreceiver performance is enabled by a 1-mm diameter quad p-i-n InGaAs photodiode having 2.5-pF capacitance per quadrant at 5-V reverse bias.