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Much attention has been paid to the photoresponse of vanaduim oxide (VOx) and amorphous silicon based microbolometer for long-wavelength infrared detection under un-cooled operation condition in recent decades. However, the outstanding physical and chemical properties of graphene and reduced graphene oxide (rGO) stimulate their potential for use in light-sensitive applications. Much less attention has been paid to investigate the performance on long-wavelength infrared detection of microbolometer using reduced graphene oxide/SiNx/vanadium oxide composite films deposited on under room temperature operation. In the research, we have proposed the novel microbolometer based on VOx/SiNx/rGO composite films replace the as-deposited VOx based microbolometer. It is noted that such extraordinary properties (high responsivity: 18,130 V/W and low NETD: 43.32 mK) of the VOx/SiNx/rGO composite presented here encourage us to contemplate on this protocol for next generation optoelectronic device engineering for infrared detection.

In this study, we study a heat transfer model, with the surface of the microbolometer device receiving radiation from blackbody constructed using a COMSOL Multiphysics simulator. We have proposed three kinds of L-type 2-leg and 4-leg with the pixel pitch of 35 &mu, m based on vanadium oxide absorbent membrane sandwiched with top passivated and bottom Si3N4 supporting films, respectively. Under the blackbody radiation, the surface temperature changes and distributions of these samples are simulated and analyzed in detail. The trend of change of the temperature dependent resistance of the four kinds of bolometer devices using the proposed heat transfer model is consistent with the actual results of the change of resistance of 4 samples irradiated with 325 K blackbody located in the front distance of 5 cm. In this paper, &Delta, T indicates the averaged differences of the top temperature on the suspended membrane and the lowest temperature on the post of legs of the microbolometers. It is shown that &Delta, T &asymp, 17 mK is larger in nominal 2-leg microbolometer device than that of 4-leg one and of 2-leg with 2 &mu, m &times, 2 &mu, m central square hole and two 7.5 &mu, m slits in suspended films. Additionally, only &Delta, 5 mK with 4-leg microbolometer device under the same radiated energy of 325 K blackbody results from the larger total thermal conductance.

In this paper, figures of merit describing the performances of infrared (IR) bolometer sensor such as thermal response time (a#x03C4;), responsivity, detectivity (D), noise equivalent power (NEP) and noise equivalent temperature difference (NETD) are estimated using numerical simulations. The proposed model is based on the analytical formulas from Frank Niklaus, et.al. Using this model, we have evaluated the performance of two-legged, uncooled infrared bolometer sensor with 52×52 a#x03BC;m2 and 35×35 a#x03BC;m2 pixel-pitch size. The bolometer sensors were fabricated by Institut National d'Optique (INO), Canada and National Chung-Shan Institute Science of Technology (NCSIST), Taiwan. Test structures including uncooled vanadium oxide bolometer FPAs were fabricated at INO to verify the agreement between the simulated and experimental data. The performance model was used at NCSIST to evaluate the improvements on design and fabrication of bolometer FPAs with pixel pitch varying form 35 a#x03BC;m to 52 a#x03BC;m.

We report on analysis and comparison of the dark current characteristics between InAs p-n and p-i-n diodes at the temperature range from 30 to 300 K. The situation that the dark current is completely due to the bulk instead of the surface leakage is made sure by passivation treatment. The experimental results agree well with a tunnel diode model in which the p-n and p-i-n diodes are described, respectively, with a linear electrical field and a constant electrical field. The diffusion current in our diodes is dominated by the electron diffusion in the p-type material. Through this model and detailed analysis, we conclude that the tunneling current can be suppressed with an intrinsic layer and a low n-type doping density while the diffusion current can be decreased with a high p-type doping density. The advantage of the p-i-n structure is not only to cut down the tunneling current but also to increase the uniformity. In terms of this model, a new p-i-n diode is designed to dramatically increase its zero-bias resistance area product and improve the detector performance. (C) 1996 American Institute of Physics.

This paper discusses a capacitor transimpedance amplifier (CTIA) designed for an infrared readout circuit. The CTIA has better gain control, high dynamic range, a stability bias point and low impedance. It applies a short-wave detector and small current source because input impedance is very small in an amplifier feedback mechanism. This research on a capacitor transimpedance amplifier (CTIA) is designed for an infrared readout circuit. It is designed, simulated and laid out using the TSMC 0.35um 2P4M CMOS 5V process. The clock rate operates at 3MHz. Layout area is 30umX30um and the array size is 20X16. The simulation current sets 0.01nA~1.3nA. The output swing is 2.8V and power consumption is 10.1 mW according to the measurement results.

This paper presents the readout circuit based on Direct Injection (DI) and Capacitive Transimpedance Amplifier (CTIA). The hybrid type of CTIA and DI was adopted as the pixel circuit's design in this paper. The two different structures were combined into unit pixels, and each pixel has two modes of readout. Furthermore, the chip was produced with TSMC 2P4M 5V technology, and the array size is 10×8. The output swing is 2.1V and power consumption is 9.4 mW, according to measurement results. The Layout area is 40um × 40um, and the two modes are selected by an external pin. The dual mode structure enables single- and dual-band infrared sensors. The readout chip can operate in 2kHz ∼ 6MHz, and the input photocurrent range is 1pA ∼ 50nA, depending on integration time; thus, it can be suitable for various detectors.

This paper proposes two kinds of readout integrated circuits for column and row interlaced dual-band infrared detectors. The experiments were simulated using TSMC 0.35μm Mixed Signal 2P4M CMOS process and operated at 3MHz clock rate. The pixel dimensions for two kinds of readout integrated circuits were also 30×30μm. The mid-wave and long-wave sense current was set from 1nA to 2nA and 6nA to 8nA, respectively. We designed a 40x16 array for the columns interlace readout circuit. The output voltage swing was 2.8V. The frame rate was 4.68kFPS. The total power consumption was less than 17.6mW. We also designed a 20x32 array for the row interlace readout circuit. The output voltage swing was 2.8V. The frame rate was 2.67kFPS. The total power consumption was less than 11.4mW. The power consumption increased when the column interlace frame rate reached the row interlace frame rate. The row interlace can decrease the layout area by sharing the column stage circuit, but the frame rate will drop to half of the single band frame rate.

A ten-stacked self-assembled InAs/GaAs quantum-dot infrared photodetector operated in the 2.5–7 μm range by photovoltaic and photoconductive mixed-mode near-room-temperature operation (⩾250 K) was demonstrated. The specific peak detectivity D* is 2.4×108 cm Hz1/2/W at 250 K. The use of high-band-gap Al0.3Ga0.7As barriers at both sides of the InAs quantum-dot structure and the long carrier recombination time are the key factors responsible for its near-room-temperature operation.

This paper discussed about a readout circuit for Quantum Dot Infrared Photodetector (QDIP) Focal-Plane-Array (FPA) imaging system. The readout circuit employed a modified regulated cascode circuit to stabilize the bias of QDIP. The readout circuit consisted of in-pixel dark current cancellation circuit, sensed current integration and in-pixel switch integration capacitor. The chip worked at 5V power supply and operated at 1MHz clock rate. Output voltage ranging from 2 volt to 4 volt was generated when the sensing current from 10nA to 100nA, the dark current was set up to 100nA. The total power consumption was less than 3.3 mW. The dimension of unit pixel was 30×30μm and the integration capacitance was about 0.24pF. The 8×8 pixels array readout circuit of in-pixel variable integration capacitors was implemented by using TSMC 0.35μm Mixed Signal 2P4M CMOS process.

The InGaAs/InP P-I-N photodiodes are grown by a metal-organic chemical vapor deposition (MOCVD) with micro-effusion tubes of hydride carrier and reaction gases. Removing top InGaAs and using SiOx coverage on the photon absorbed area leads to enhance responsivity (~3 AAV) and quantum efficiency (>85%). And using Zn diffused to top ring InGaAs results in good ohmic contact region.

The vertical cavity surface emitting laser (VCSEL) based on graded distributed Bragg reflectors (DBR) consisted of a top mirror of 20 pairs of AlxGa1-xAs/AlyGa1-yAs (x=0~0.9, y=0~0.12) quarter-wave stacks and a bottom mirror of 34 pairs of AlyGa1-yAs/AlxGa1-xAs quarter-wave stacks has been demonstrated. Using two proposed transfer matrix methods, the simulation of DBR reflectivity depending on temperature refractive index of AlxGa1-xAs and AlyGa1-yAs are discussed and investigated. The simulation results could be achieved to well predicted the DBR performance under operating temperature variances, i.e., the temperature on varying reflectivity and full width half maximum (FWHM), wavelength stop-band shifts of the laser reflector, where using the multi-layer films evolution software of essential Macleod and modified transfer matrix method, respectively. Under our simulation, assuming the physically VCSEL device feature such as the linear grading DBR structure sandwiched with a n-type GaAs substrate and air films, we have systematically studied the temperature effects on the key parameters of top and bottom DBR schemes. In contrast with the temperature dependent DBR on the 850nm-VCSEL characteristics simulated with the above two transfer methods, the temperature varying spectra of VCSEL are agreed with the our simulated results presented in this paper. Also the temperature dependent model of DBR based on refractive index of graded multi-AlxGa1-xAs/ AlyGa1-yAs has been proposed. So, a series of optoelectronic measurements experimentally confirm our results again. The maximum reflectivity of the top and bottom DBRs are 96.4 and 99.98%, respectively. The central wavelengths of the bandwidth spectra in the top and bottom DBR are same. i.e., 840nm. These results can be obtained the criteria for the high performance VCSEL design. The far-field patterns of transverse electromagnetic fields confined in

The InAs/GaAs quantum dot (QD) edge light emitting diode (LED) emitting at a wavelength of 1 /spl mu/m has been fabricated which exhibits very small wavelength shift of 0.22 nm/K and the full width at half maximum (FWHM) broadening shift of 0.04 nm/K. Detailed temperature characteristics over a range from 20 to 300 K are presented.

In this letter, the effect of extraordinary transmission of periodic metal hole arrays is directly integrated into the quantum dot infrared photodetector with broadband response. It is found that the detector response is strongly modulated by the extraordinary transmission from the excitation of surface plasmon.

The current leakages of InAs photodiodes have been systematically studied by adding undoped layers having thicknesses of 0, 0.30, and 0.72 μm between the p–n junction. At reverse bias V=−0.5 V, the dark currents of the InAs p–i–n diodes with undoped layer thicknesses of 0, 0.30, and 0.72 μm are about 5×10−6, 7×10−8, and 1×10−10 A, respectively, at 77 K. The leakage current of the InAs p–n diode was successfully reduced by adding 0.72-μm-thick undoped layer between the p–n junction.