PIN Photodetector Research Articles

A 25Gbaud PAM-4 Linear Burst-Mode Receiver With Analog Gain- and Offset Control in 0.25μm SiGe:C BiCMOS

We present a burst-mode receiver (BMRx) whose architecture and design is optimized for linear operation up to 25Gbaud modulation rates. The linear burst-mode receiver (LBMRx) consists of a fixed-gain transimpedance amplifier, followed by a three-stage post-amplifier and a 50-ohm output buffer. The gain of the post-amplifier stages and dc-offsets of the datapath can be quickly adjusted from one burst to the next through combined feedforward (providing rapid settling) and feedback (providing accurate gain and offset control) automatic-gain-control (AGC) and automatic-offset-control (AOC) loops. When receiving 25G NRZ and assembled with a PIN photodetector, a sensitivity of −18.1 dBm and overload of at least 3.5 dBm was measured at a bit-error-rate (BER) of 1E−2, thus supporting a 21.6 dB input dynamic range. When receiving 4-level pulse amplitude modulation (PAM-4), a sensitivity of −11.4 dBm and overload of at least 4.4 dBm was measured at a low-density-parity-check (LDPC) BER reference of 1E−2, supporting 15.8 dB dynamic range. Between −10 up to 3.5 dBm the LBMRx also features internal start-of-burst (SOB) and end-of-burst (EOB) detection. Over the specified input dynamic range, the total harmonic distortion (THD) remains below 5%. The receiver was designed in a 0.25 $\mu \text{m}$ SiGe:C BiCMOS technology, occupying an area of $1.32\times 1.05$ mm2 and consumes 280 mW from a 2.5 V supply. This LBMRx can be used as front-end for new upcoming passive optical networks (PONs) that may require, e.g., electronic equalization (to overcome bandwidth limitations of opto-electronic components) or dispersion compensation; or may be used to support advanced modulation formats requiring linear operation.

Silicon-based high-responsivity GeSn short-wave infrared heterojunction phototransistors with a floating base.

We demonstrate silicon-based $p \text{-} n \text{-} p$p-n-p floating-base GeSn heterojunction phototransistors with enhanced optical responsivity for efficient short-wave infrared (SWIR) photodetection. The narrow-bandgap GeSn active layer sandwiched between the $p \text{-} {\rm Ge}$p-Ge collector and $n \text{-} {\rm Ge}$n-Ge base effectively extends the photodetection range in the SWIR range, and the internal gain amplifies the optical response by a factor of more than three at a low driving voltage of 0.4 V compared to that of a reference GeSn $p \text{-} i \text{-} n$p-i-n photodetector (PD). We anticipate that our findings will be leveraged to realize complementary metal-oxide-semiconductor-compatible, sensitive, low driving voltage SWIR PDs in a wide range of applications.

Wave-Guided Lateral-Configured Ge-Ge-Si Photodetectors Obtained by Rapid Melting Growth Technique

The synergy of photonic and electronic signal transmission in the near-infrared spectrum is an ideal solution for optoelectronic integrated circuits in high-speed communication systems. In this study, we fabricated high-quality germanium mesa on Si by rapid-melting growth technique for a PIN photodetector. The quality of Ge was investigated through standard Raman spectroscopy and electronic microscopy. Rather than a single-crystalline Ge mesa, a polycrystalline structure differs from those of our previous reports, and may be caused by the multiple vicinities with oxide and Si. Ge/Ge/Si PIN photodetector and a Si waveguide was fabricated and measured to study the photodetector’s I-V characteristics at near-infrared spectrum. The normalized power-dependent current enhancement and photoresponsivity were investigated to reveal the effect of Ge mesa quality. This study demonstrated that a high-quality Ge mesa can be employed for optoelectronic integrated circuit with high photoelectric conversion efficiency and responsivity by a Si-based integrated circuit fabrication process.

Self-powered silicon PIN photoelectric detection system based on triboelectric nanogenerator

When sensor networks for the Internet of Things (IoT) are applied on a large scale, it's urgent to investigate self-powered photoelectric detection system without external power supply. Therefore, we propose a self-powered photo-detection system based on the triboelectric nanogenerator (TENG) in which the silicon PIN photodetector is powered by a paper-based contact separated TENG. The silicon PIN photodetectors are based on mature silicon processing technology, which is suitable for large scale production. The TENG is connected to the detector through the rectifier bridge circuit. Owing to the internal photoelectric effect of the detector and the TENG impedance matching effect, the equivalent resistance of the detector decreases when light is applied to the surface of the photodetector and the output voltage of the TENG changes accordingly. We investigate the output characteristics of the photoelectric detection system under different illumination intensities and propose a circuit model to analyze the influence of the current on the detection range. Finally, we use light-emitting diodes (LEDs) as display devices to characterize the detected light intensity for applicable self-powered photo-detection system.

Electrical characteristics analysis of PIN detector with different doping concentration levels of N and P-type materials

Present work involves the analysis of electrical characteristics of PIN photodetector with different doping concentration of P and N-type regions which serve as good ohmic contacts. It is possible to improve the basic electronic properties of a PIN photodetector with slight changes in doping levels. So, critical investigation of limit of heavy doping levels of N and P-type materials is very important. Hence this paper illustrates the importance of selecting the optimum value of doping levels when the doping level of intrinsic region remains fixed. Moreover, it provides the analysis of cathode current, recombination rate; electric field; spectral and transient responses of PIN detector to highlight the effect of doping concentration below or beyond the optimum value (1018) for the selected detector. For large photocurrent and fast switching operation there is a need to define the optimum level of the doping concentration of P and N-type layers in PIN detector. In this paper, the performance of Silicon based PIN photodiode’s intensity response within 100–1000 nm wavelength range is demonstrated. The present work will be beneficial in different applications such as detection of light in Ultraviolet range and for high-speed switching circuits.

Comprehensive Study on Chip-Integrated Germanium Pin Photodetectors for Energy-Efficient Silicon Interconnects

Optical interconnects are promising alternatives to copper-based wirings in on-chip communications. Recent advances in integrated group-IV nanophotonics should address a range of challenges related with speed, energy consumption, and cost. Monolithically integrated germanium pin photodetectors on silicon-on-insulator (SOI) waveguides are indispensable devices in this buoyant research field. Here, we comprehensively investigate the opto-electrical properties of hetero-structured pin photodetectors. All photodetectors were fabricated on top of 200-mm SOI substrates using industrial-scale semiconductor manufacturing processes. Under a low-bias voltage supply of 1 V, pin photodetectors exhibit dark-currents from 5 nA to 100 nA, dark current densities from 0.404 A/cm 2 to 0.808 A/cm 2 , responsivities in a range of 0.17 A/W to 1.16 A/W, and cut-off frequencies from 7 GHz to 35 GHz, respectively. Such achievements make them promising for use in power-efficient optical links operating at 40 Gbps, with a device energy dissipation of only few fJ per bit.

Plasmonics-Integrated Ge PIN-Photodetectors

Refractive index sensors can be designed for high sensitivities at small device foot-print. Using a complementary metal-oxide-semiconductor compatible process for fabrication paves the way to cheap devices enabling integrated biosensors. We present results on combining vertical Ge PIN photodetectors with metallic nanostructures such as Al nanohole arrays placed directly on top of the diode. The interaction of plasmonic resonances and photonic modes such as waveguide modes or optical modes in nanostructured photodetectors can potentially be exploited to design refractive index sensors with very high sensitivities. We discuss how the interplay of material properties and device geometry can be tailored for applications in integrated biosensing.

Simultaneous photonic generation of multiple chirp and unchirp microwave waveform with frequency multiplying capability for optical beam forming system

A photonic technique based on the Mach–Zehnder Modulator and the dual parallel Mach–Zehnder modulator is proposed for the simultaneous generation of multiple chirp and unchirp microwave waveform with frequency multiplying capability for efficient beam steering applications. There is provision to obtain a single chirp signal of a particular center frequency and chirp rate from a multiple chirp signal without any alternation in the experimental setup. In the proposed methodology, the PIN photodetector is used for the detection of 12 GHz unchirp microwave waveform showing the frequency doubling characteristics and the balance photodetector is used for the detection of multiple chirp signal with frequency components 6, 12, and 18 GHz. The same experimental setup is used to generate dual linear chirp microwave signal of 12 GHz center frequency. This can be achieved by adjusting the bias voltage of the phase modulator. Time bandwidth product and bandwidth of the signal are 18.33 and 410 MHz, respectively. This technique is tunable in frequency, but the generation of higher frequency microwave signals is limited by the speed and bandwidth of the Mach–Zehnder Modulator and photodetector. The novelty of our proposed scheme is that we are going to drive MZM by chirp RF signal to multiply the chirp rate in manifold. To the best of our knowledge the effect of chirp microwave signal on photonic highly steerable beam forming system has not yet been studied experimentally in past, which we are targeting under this paper. It is expected that the range of beam steering performance should be improved substantially as compared to previously reported results.

SiGe Photo-Transistor for Low-Cost SSMF-Based Radio-Over-Fiber Applications at 850nm

This paper investigates the possibility of implementing SiGe Hetero-junction bipolar Photo-Transistor (HPT) within low cost and low power consumption Radio-over-Fiber (RoF) systems based on standard single mode fiber (SSMF) operating in the first optical window for wireless communication networks scenarios. The SiGe HPT under study has potential lower cost compared to standard PIN photo-detectors as it is fabricated through the consolidated SiGe bipolar transistor process technologies, allowing the possible integration with Si-based circuits. Various operation modes of the photo-transistor (such as three-terminals and two-terminals) are investigated, analyzing their impact on the SSMF-based RoF link in terms of gain and noise (including modal noise fluctuations) for a frequency range up to 2.5 GHz. A 20 MHz LTE transmission is finally demonstrated as example of possible applications of the studied RoF link.

Integrated VCSOA and PIN with high sensitivity

An integrated vertical cavity semiconductor optical amplifier (VCSOA) and PIN photodetector was proposed in attempting to raise the sensitivity in high speed fiber-optic communication systems. Two slightly different structures have been studied under this configuration. For the cascade and the resonance structure, our simulation results showed that their sensitivity could reach -33dBm and -36dBm at a bit rate of 10Gb/s, respectively. We also managed to fabricate the cascade structure and demonstrated a 7dBm improvement on sensitivity as compared to the conventional PIN photodetector.

Few-Layer MoS2/a-Si:H Heterojunction Pin-Photodiodes for Extended Infrared Detection

Few-layer molybdenum disulfide (FL-MoS$_2$) films have been integrated into amorphous silicon (a-Si:H) pin photodetectors. To achieve this, vertical a-Si:H photodiodes were grown by plasma-enhanced chemical vapor deposition (PE-CVD) on top of large-scale synthesized and transferred homogeneous FL-MoS$_2$. This novel detector array exhibits long-term stability (more than six month) and outperforms conventional silicon-based pin photodetectors in the infrared range (IR, $\lambda$ = 2120 nm) in terms of sensitivities by up to 50 mAW$^{-1}$. Photodetectivities of up to 2 x 10$^{10}$ Jones and external quantum efficiencies of 3 % are achieved. The detectors further feature the additional functionality of bias-dependent responsivity switching between the different spectral ranges. The realization of such scalable detector arrays is an essential step towards pixelated and wavelength-selective sensors operating in the IR spectral range.

The detailed analysis of wavefunction overlaps for InAs/AlSb/GaSb based N-structure type-II SL pin photodetectors

We report on a detailed analysis of electron and hole wave functions with their overlap integrals for InAs/AlSb/GaSb based N-structure type-II superlattice (T2SL) pin detectors under applied reverse bias. Bandgap energies and superlattice minibands are performed by envelope function approximation using pseudopotential method for input parameters such as effective masses and envelope functions at Γ point. The layer thickness of detector structure is designed to operate in the long wavelength infrared range given with the maximum overlap of around 8.6 μm. Electron wave functions show strong localizations in the neighboring wells under low electrical fields resulting with lower overlap integrals. An increase in the electrical field causes strong overlap by reduced localizations.

High-speed waveguide integrated silicon photodetector on a SiN-SOI platform for short reach datacom.

We present a waveguide integrated high-speed Si photodetector integrated with a silicon nitride (SiN) waveguide on an silicon-on-insulator (SOI) platform for short reach data communication in a 850nm wavelength band. We demonstrate a waveguide couple Si pin photodetector responsivity of 0.44 A/W at 25V bias. The frequency response of the photodetector is evaluated by the coupling of a femtosecond laser source through an SiN grating coupler of the integrated photodetector. We estimate a 3dB bandwidth of 14GHz at 20V bias which, to the best of our knowledge, is the highest reported bandwidth for a waveguide integrated Si photodetector. We also present detailed optoelectronic DC and AC characterization of the fabricated devices. The demonstrated integrated photodetector could enable an integrated solution for scaling of short reach data communication and connectivity.

25 Gbps low-voltage hetero-structured silicon-germanium waveguide pin photodetectors for monolithic on-chip nanophotonic architectures

Near-infrared germanium (Ge) photodetectors monolithically integrated on top of silicon-on-insulator substrates are universally regarded as key enablers towards chip-scale nanophotonics, with applications ranging from sensing and health monitoring to object recognition and optical communications. In this work, we report on the high-data-rate performance pin waveguide photodetectors made of a lateral hetero-structured silicon-Ge-silicon (Si-Ge-Si) junction operating under low reverse bias at 1.55 μm. The pin photodetector integration scheme considerably eases device manufacturing and is fully compatible with complementary metal-oxide-semiconductor technology. In particular, the hetero-structured Si-Ge-Si photodetectors show efficiency-bandwidth products of ∼9 GHz at −1 V and ∼30 GHz at −3 V, with a leakage dark current as low as ∼150 nA, allowing superior signal detection of high-speed data traffic. A bit-error rate of 10−9 is achieved for conventional 10 Gbps, 20 Gbps, and 25 Gbps data rates, yielding optical power sensitivities of −13.85 dBm, −12.70 dBm, and −11.25 dBm, respectively. This demonstration opens up new horizons towards cost-effective Ge pin waveguide photodetectors that combine fast device operation at low voltages with standard semiconductor fabrication processes, as desired for reliable on-chip architectures in next-generation nanophotonics integrated circuits.

Physical modelling of InGaAs–InAlAs APD and PIN photodetectors for >25 Gb/s data rate applications

Validated SILVACO physical models were exploited to optimise electrical and optical characteristics of 1.5 μm wavelength InAlAs-InGaAs Avalanche photodiodes and InGaAs PIN diodes. Optimised SILVACO models were created by selectively thinning down the absorption layers to further reduce the carrier transit time. Further optimisation was accomplished by scaling the light window aperture and mesa area sizes with the aim of reducing the device capacitances. The optimised PIN diode provides a maximum opto-electric bandwidth of 35 GHz with a current responsivity of 0.4 A/W under -5 V bias voltage and 10 μW incident optical power. At 1 μW incident optical power, the maximum opto-electric bandwidth and current responsivity of the optimised avalanche diode is 21 GHz and 1.4 A/W under -21.5 V bias voltage. The optimised APD and PIN photo-detectors are capable of working at a data rate of up to 25 and 40 Gb/s, respectively.

Design impact on the performance of Ge PIN photodetectors

This article presents the impact of epitaxial quality, contact resistance and profile of Ge PIN photodetectors (PDs) on dark current and responsivity. The PD structures were processed with either s ...

Modeling and simulation analysis of PIN photodetector

为了优化PIN光电探测器响应特性，首先依据载流子速率方程，并考虑芯片寄生参量和封装寄生参量，建立光电探测器的等效电路模型。然后仿真分析了反偏电压、I区宽度、光敏面、芯片寄生电阻和电容、封装寄生电阻、电容和电感对光电探测器脉冲响应特性和频率响应特性的影响。结果表明：通过增大反偏电压，减小光敏面和寄生参量(芯片寄生电容和电阻，封装寄生电容和电阻)，选取合适的I区宽度，利用引线电感的谐振效应现象，可以抑制脉冲响应波形畸变，提高频率响应带宽。

Error performance of optical wireless communication systems exercising BPSK subcarrier intensity modulation in non-Kolmogorov turbulent atmosphere

Abstract Subcarrier intensity modulation (SIM) scheme is preferred due to efficient bandwidth usage superiority over other modulation techniques such as on–off keying (OOK), pulse position modulation (PPM). In this paper, we investigate the bit error rate (BER) performance of optical wireless communication (OWC) system using binary phase shift keying (BPSK) SIM in non-Kolmogorov turbulent atmosphere. We pay attention to the weak turbulence conditions by using Rytov approximation and considering that the receiver is a PIN photodetector. Propagating beam type is Gaussian. It is seen that BER performance of the BPSK SIM OWC is significantly affected from non-Kolmogorov power law exponent, load resistor, responsivity of the PIN photodetector, bandwidth, beam source size, turbulence strength and noise factor.

Ge photodetector monolithically integrated with amorphous Si waveguide on wafer-bonded Ge-on-insulator substrate.

We present a proof-of-concept demonstration of a Ge/a-Si hybrid photonic integrated circuit platform utilizing a high-quality Ge-on-insulator (GeOI) wafer fabricated by wafer bonding technology. Amorphous Si (a-Si) formed by PECVD is found to be a promising alternative to conventional Si passive waveguides on a SiO2 BOX. Taking advantage of the high crystal quality of the Ge active layer and the easy fabrication of an a-Si waveguide, a low-dark-current Ge waveguide PIN photodetector monolithically integrated with an a-Si passive waveguide is successfully demonstrated on a GeOI wafer.

A study on the voltage-dependent response of a GaInNAs-based pin photodetector with a quasi-cavity

We present a characterisation of a GaInNAs/GaNAs quantum well-based photodetector with a bottom distributed Bragg reflector (quasi-cavity). The detector is designed to be used at the 1.3 μm optical fibre communication window. The quantum efficiency of the photodetector is measured as 24% at 1286 nm under −2 V applied reverse bias. As the reverse bias voltage is increased, a carrier multiplication-related increase and oscillations are observed in the voltage-dependent responsivity curve. The observed carrier multiplication is explained by the high electrical field-induced impact ionisation mechanism in the pin junction region, while the observed voltage-dependent oscillations are explained by the Franz–Keldysh effect (FKE). At the wavelength of 1286 nm, which is close to the absorption wavelength of the active region of the photodetector, FKE-related oscillations (FKOs), start at very low reverse bias values and the responsivity of the photodetector is dominated by FKOs. On the other hand, FKOs quench at higher wavelengths and an impact ionisation-related increase at the voltage-dependent responsivity curve dominates. At λ = 1310 nm, only impact ionisation mechanisms have an effect over the R (V) curve. The multiplication factor for 1310 nm is calculated as M = 12 at room temperature. The applied electric field and excitation wavelength dependence of the absorption coefficient is calculated and a good match with the experimental results at the applied voltages is achieved.