Showing papers on "Responsivity published in 2002"
TL;DR: In this paper, a sputter deposition of n-ZnO films on p-Si substrates was used to construct a photodiode with an Ar/O 2 ratio of 6:1.
201 citations
TL;DR: In this article, a simple design technique that allows the fabrication of UV/blue-selective avalanche photodiodes in a conventional CMOS process is presented, which achieves a very low dark current of only 400 pA/mm/sup 2/, an excess noise factor F=7 at /spl lambda/=400 nm and a good gain uniformity.
Abstract: We present a simple design technique that allows the fabrication of UV/blue-selective avalanche photodiodes in a conventional CMOS process. The photodiodes are fabricated in a twin tub 0.8 /spl mu/m CMOS technology. An efficient guard-ring structure is created using the lateral diffusion of two n-well regions separated by a gap of 0.6 /spl mu/m. When operated at a multiplication gain of 20, our photodiodes achieve a very low dark current of only 400 pA/mm/sup 2/, an excess noise factor F=7 at /spl lambda/=400 nm and a good gain uniformity. At zero bias voltage, the responsivity peaks at /spl lambda/=470 nm, with 180 mA/W. It corresponds to a 50% quantum efficiency. Successive process steps are simulated to provide a comprehensive understanding of this technique.
157 citations
TL;DR: In this paper, a dot-in-a-well detector operating at T =78 K with λp∼7.2 µm and a spectral width of 35% is reported.
Abstract: Normal incidence InAs/In0.15Ga0.85As dots-in-a-well detectors operating at T=78 K with λp∼7.2 μm and a spectral width (Δλ/λ) of 35% are reported. The peak at 7.2 μm is attributed to the bound-to-bound transitions between the ground state of the dot and the states within the InGaAs well. A broad shoulder around 5 μm, which is attributed to the bound-to-continuum transition, is also observed. Calibrated blackbody measurements at a device temperature of 78 K yield a peak responsivity of 3.58 A/W (Vb=−1 V), peak detectivity=2.7×109 cm Hz1/2/W (Vb=−0.3 V), conversion efficiency of 57% and a gain ∼25.
155 citations
TL;DR: In this paper, the authors reported the most recent advance in the area of type II InAs/GaSb superlattice photovoltaic detectors that have cutoff wavelengths beyond 25 μm, with some at nearly 32 μm.
Abstract: We report the most recent advance in the area of type II InAs/GaSb superlattice photovoltaic detectors that have cutoff wavelengths beyond 25 μm, with some at nearly 32 μm. The photodiodes with a heterosuperlattice junction showed Johnson noise limited peak detectivity of 1.05×1010 cm Hz1/2/W at 15 μm under zero bias, and peak responsivity of 3 A/W under −40 mV reverse bias at 34 K illuminated by ∼300 K background with a 2π field-of-view. The maximum operating temperature of these detectors ranges from 50 to 65 K. No detectable change in the blackbody response has been observed after 5–6 thermal cyclings, with temperature varying between 15 and 296 K in vacuum.
138 citations
TL;DR: In this paper, two different quantum-cascade-laser structures as photodetectors were evaluated, one two-phonon-resonance structure and the other one a 9.3 μm bound-to-continuum transition laser.
Abstract: We evaluated two different quantum-cascade-laser structures as photodetectors. The first device was a 5.3 μm two-phonon-resonance structure, and the second one a 9.3 μm bound-to-continuum transition laser. The 5.3 μm structure had a peak responsivity of 120 μA/W at 2200 cm−1 and functioned up to 325 K. On the other hand, the 9.3 μm device also worked up to 297 K but had a lower responsivity of 50 μA/W at 1330 cm−1. Since the absorption peak of these devices can be shifted by applying an external bias, we envision interesting applications in free-space optical telecommunications.
132 citations
TL;DR: In this paper, the temperature dependence of the photoresponse of very long wavelength infrared type-II InAs/GaSb superlattice based photovoltaic detectors grown by molecular-beam epitaxy was reported.
Abstract: We report on the temperature dependence of the photoresponse of very long wavelength infrared type-II InAs/GaSb superlattice based photovoltaic detectors grown by molecular-beam epitaxy. The detectors had a 50% cutoff wavelength of 18.8 μm and a peak current responsivity of 4 A/W at 80 K. A peak detectivity of 4.5×1010 cm Hz1/2/W was achieved at 80 K at a reverse bias of 110 mV. The generation–recombination lifetime was 0.4 ns at 80 K. The cutoff wavelength increased very slowly with increasing temperature with a net shift from 20 to 80 K of only 1.2 μm.
127 citations
TL;DR: In this article, the InAs quantum dot infrared photodetectors that utilize In0.15Ga0.85As strain-relief cap layers exhibited normal-incidence photoresponse peaks at 8.3 or 8.8 μm for negative or positive bias, respectively.
Abstract: We report InAs quantum dot infrared photodetectors that utilize In0.15Ga0.85As strain-relief cap layers. These devices exhibited normal-incidence photoresponse peaks at 8.3 or 8.8 μm for negative or positive bias, respectively. At 77 K and −0.2 V bias the responsivity was 22 mA/W and the peak detectivity D* was 3.2×109 cm Hz1/2/W.
102 citations
TL;DR: In this article, a backilluminated GaN/Al 0.18Ga0.82N heterojunction ultraviolet (UV) photodetector with high internal gain based on metal-semiconductor-metal structures was achieved.
Abstract: We report on a backilluminated GaN/Al0.18Ga0.82N heterojunction ultraviolet (UV) photodetector with high internal gain based on metal-semiconductor-metal structures. A narrow band pass spectral response between 365 and 343 nm was achieved. When operating in dc mode, the responsivity reaches up to the order of 102 A/W under weak UV illumination, which is due to enormous internal gain up to 103. The linear dependence of photocurrent on bias and its square root dependence on optical power are found and explained by a trapping and recombination model. The high photocurrent gain is attributed to trapping and recombination centers with an acceptor character induced by dislocations in GaN.
82 citations
TL;DR: In this article, a near-infrared p-i-n photodetectors with Ge/Si self-assembled quantum dots was investigated. But the photoresponse of the device covers the near infrared spectral range up to 1.5 μm.
Abstract: We have investigated near-infrared p-i-n photodetectors with Ge/Si self-assembled quantum dots. The self-assembled quantum dots were grown by chemical vapor deposition on Si(001). A vertical stacking of 20 layers of quantum dots was inserted into a near-infrared waveguide obtained with a Si0.98Ge0.02 alloy. The samples were processed into ridge waveguides. The photoresponse of the device covers the near-infrared spectral range up to 1.5 μm. At room temperature, a responsivity of 210 mA/W is measured at 1.3 μm and 3 mA/W at 1.5 μm. The photocurrent is compared to the photoluminescence and to the absorption of the quantum dots measured in the waveguide geometry. At room temperature, the onset of the absorption is around 1.9 μm (0.65 eV). The photocurrent is blueshifted as compared to the absorption.
78 citations
TL;DR: In this paper, a silicon lateral trench photodetector that decouples the carrier transit distance from the light absorption depth, enabling both high speed and high responsivity is presented.
Abstract: 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.
67 citations
TL;DR: In this paper, a new photodiode for the UV/blue spectral range, which can be integrated monolithically with CMOS circuits, is presented, achieving a responsivity of 0.23 A/W corresponding to a quantum efficiency /spl eta/ of 70% [with an antireflection coating] and rise and fall times of 1.0 ns and 1.1 ns, respectively.
Abstract: A new photodiode for the UV/blue spectral range, which can be integrated monolithically with CMOS circuits, is presented. Such optoelectronic integrated circuits (OEICs) with a high sensitivity in the UV/blue spectral range are needed in near-future optical storage systems like digital versatile disk (DVD) or digital video recording (DVR). At 400 nm, our so-called finger photodiode achieves a responsivity of 0.23 A/W corresponding to a quantum efficiency /spl eta/ of 70% [with an antireflection coating (ARC)] and rise and fall times of 1.0 ns and 1.1 ns, respectively. The finger photodiode can be used in the red spectral range, too. At 638 nm, the responsivity is 0.49 A/W (/spl eta/=95%) and rise and fall times of less than 2.3 ns are achieved. For the integration of the finger photodiode in an industrial 1 /spl mu/m twin-well CMOS process, only one additional mask is needed in order to block out the threshold voltage implantation in the photo-active region.
TL;DR: In this paper, a photoconductive detector based on low-temperature-grown GaAs which is vertically integrated with terahertz spiral antennas is presented, with a non steady-state velocity overshoot effect.
Abstract: We report on the development of a photoconductive detector based on low-temperature-grown GaAs which is vertically integrated with terahertz spiral antennas. A non steady-state velocity overshoot effect was expected in the photoresponse with a responsivity of 0.04 A/W at a bias voltage of 8 V. Photomixing experiments using two optical 0.8 μm beating lasers show a 3 dB bandwith of 700 GHz with a radiation power at terahertz frequency of 0.5 μW under 2×30 mW optical pumping.
TL;DR: In this paper, the vertical and lateral geometry GaN-based Schottky barrier photodetectors have been implemented, using similar quality material and the same fabrication process.
Abstract: Vertical and lateral geometry GaN-based Schottky barrier photodetectors have been implemented, using similar quality material and the same fabrication process. The vertical detector exhibits two orders of magnitude higher responsivity. This is attributed to improved ohmic backcontacts, due to the highly doped buried layer. The vertical detectors exhibits also lower 1/f noise level, which is attributed to the reduced effect of dislocations on the carrier transport, resulting in lower mobility fluctuations. The vertical detector normalized detectivity is four orders of magnitude higher.
TL;DR: In this article, small-area antimonide-based backward diodes for zero-bias millimeter-wave detection have been fabricated using high-resolution I-line stepper lithography, allowing accurate control of the small device active area required for operation at W-band.
Abstract: Small-area antimonide-based backward diodes for zero-bias millimeter-wave detection have been fabricated and tested. The devices were fabricated using high-resolution I-line stepper lithography, allowing accurate control of the small device active area required for operation at W-band. The devices exhibit excellent measured performance from 1-110 GHz, with responsivities when driven from a 50-/spl Omega/ source of 2540 V/W at 95 GHz. This translates to a projected responsivity of 11.5 /spl times/ 10/sup 3/ V/W at 95 GHz for a conjugately matched detector. The compression characteristics of the detectors have been measured, with 1.2 dB of responsivity compression for an input power of 8 /spl mu/W.
TL;DR: In this article, a superlinear enhancement of responsivity is observed when scaling down, in agreement with a model that includes optical absorption and the variation of the space-charge regions with bias.
Abstract: Metal-semiconductor-metal ultraviolet (UV) detectors with finger width and pitch ranging from 0.5 to 4 μm have been fabricated on GaN. A superlinear enhancement of responsivity is observed when scaling down, in agreement with a model that includes optical absorption and the variation of the space-charge regions with bias. No degradation is found in terms of UV/visible contrast or photocurrent linearity.
TL;DR: An InAs/AlGaAs quantum-dot infrared photodetector based on bound-to-bound intraband transitions in undoped InAs quantum dots is reported in this article.
Abstract: An InAs/AlGaAs quantum-dot infrared photodetector based on bound-to-bound intraband transitions in undoped InAs quantum dots is reported. AlGaAs blocking layers were employed to achieve low dark current. The photoresponse peaked at 6.2 /spl mu/m. At 77 K and -0.7 V bias, the responsivity was 14 mA/W and the detectivity, D*, was 10/sup 10/ cm/spl middot/Hz/sup 1/2//W.
TL;DR: In this article, a two-dimensional array of antenna-coupled microbolometers is demonstrated as an area receiver using the response of micro-bolometers to visible frequencies, and a diagnostic scan in the visible was performed on these arrays which allowed measurement of their homogeneity.
Abstract: Antenna-coupled microbolometers are known for having short time constants and high responsivity, but their small dimensions make them unsuitable for imaging applications where a typical pixel area is generally greater than 20 × 20 μm2. In this paper a two dimensional array of antenna-coupled microbolometers is demonstrated as an area receiver. Using the response of microbolometers to visible frequencies a two-dimensional diagnostic scan in the visible was performed on these arrays which allowed measurement of their homogeneity. Frequency response measurements gave time constants around 130 nsec, similar to the ones obtained for single element microbolometers which indicates that a detector of virtually any size can be fabricated without sacrificing time response. Response and noise measurements show lower noise and higher responsivity compared to single element microbolometers. These results make two-dimensional arrays of antenna-coupled microbolometers a promising option for development of pixels in infrared focal plane arrays.
TL;DR: Iridium oxide (IrO2) was used as the Schottky barrier materials of GaN metal-semiconductor-metal (MSM) ultraviolet photodetector as discussed by the authors.
Abstract: Iridium oxide (IrO2) was used as the Schottky barrier materials of GaN metal–semiconductor–metal (MSM) ultraviolet photodetector. Annealing an Ir contact at 500 °C under O2 ambient, the reverse leakage current density at −5 V reduced by the four orders of magnitude, to ∼10−6 A/cm2. Simultaneously, Schottky barrier height and optical transmittance increased to 1.48 eV and 74.8% at 360 nm, respectively. The dramatic improvement originated from the formation of IrO2 by the annealing, resulting in the increase in the responsivity of the GaN MSM photodetector by one order of magnitude, in comparison with the photodetector with Pt Schottky contact.
TL;DR: In this paper, a transfer-matrix method was adopted to calculate both the energy levels and the wave functions of InGaAs/AlGaAs quantum well structures for infrared detection.
Abstract: InGaAs/AlGaAs quantum well structures have been shown to be versatile for infrared detection. By changing the material composition, one can tune the detection wavelength from 2 to 35 μm and beyond. However, there have been few systematic calculations on the absorption wavelength of these structures with respect to their structural parameters. In this work we have adopted the transfer-matrix method to calculate both their energy levels and the wave functions. From this calculation, the absorption and the responsivity spectra of the structures can be predicted. The theory agrees with the experimental result of the test structures. Supported by the experimental evidence, we applied the calculation to a general class of midwavelength detectors and thus established a useful guideline for the detector design in this wavelength range.
TL;DR: In this paper, the performance of AlGaN metal-semiconductor-metal (MSM) photodetectors grown on Si(111) was investigated, and it was shown that the growth of an adequate AlN buffer layer is critical to achieve visible-blind devices, and that its role as an effective electrical insulator of the conductive substrate was more efficient for N-excess AlN growth.
Abstract: The performance of AlGaN metal–semiconductor–metal (MSM) photodetectors grown on Si(111) is presented in this article. It is shown that the growth of an adequate AlN buffer layer is critical to achieve visible-blind devices, and that its role as an effective electrical insulator of the conductive substrate was found to be more efficient for N-excess AlN growth. The increase of Al content produced a transition from photoconductor to MSM photodiode behaviour, as determined from the detector responsivity, temporal response, and UV/visible contrast. The effect of the contact metal on photoconductive gain and UV/visible contrast was also studied.
TL;DR: A computer-based simulation of the color differences between the sets of responsivity functions was built, which allowed a user to load a spectral radiance or a spectral reflectance data file and display the tristimulus match predicted by each of the seven sets ofresponsivity functions.
Abstract: The use of colorimetry within industry has grown extensively in the last few decades. Central to many of today's instruments is the CIE system, established in 1931. Many have questioned the validity of the assumptions made by Wright1 and Guild,2 some suggesting that the 1931 color-matching functions are not the best representation of the human visual system's cone responses. A computational analysis was performed using metameric data to evaluate the CIE 1931 color-matching functions as compared to with other responsivity functions. The underlying assumption was that an optimal set of responsivity functions would yield minimal color-difference error between pairs of visually matched metamers. The difference of average color differences found in the six chosen sets of responsivity functions was small. The CIE 1931 2° color-matching functions on average yielded the largest color difference, 4.56 ΔE. The best performance came from the CIE 1964 10° color-matching functions, which yielded an average color difference of 4.02 ΔE. An optimization was then performed to derive a new set of color-matching functions that were visually matched using metameric pairs of spectral data. If all pairs were to be optimized to globally minimize the average color difference, it is expected that this would produce an optimal set of responsivity functions. The optimum solution was to use a weighted combination of each set of responsivity functions. The optimized set, called the Shaw and Fairchild responsivity functions, was able to reduce the average color difference to 3.92 ΔE. In the final part of this study a computer-based simulation of the color differences between the sets of responsivity functions was built. This simulation allowed a user to load a spectral radiance or a spectral reflectance data file and display the tristimulus match predicted by each of the seven sets of responsivity functions. © 2002 Wiley Periodicals, Inc. Col Res Appl, 27, 316–329, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10077
TL;DR: In this article, a complementary metaloxide-semiconductor (CMOS) monolithically integrated photoreceiver is presented, which operates at 8 Gb/s with 2dBm average input optical power and a bit error rate of less than 10/sup -9/.
Abstract: A complementary metal-oxide-semiconductor (CMOS) monolithically integrated photoreceiver is presented. The circuit was fabricated in a 130-nm unmodified CMOS process flow on 2-/spl mu/m-thick silicon-on-insulator substrates. The receiver operated at 8 Gb/s with 2-dBm average input optical power and a bit error rate of less than 10/sup -9/. The integrated lateral p-i-n photodetector was simultaneously realized with the amplifier and had a responsivity of 0.07 A/W at 850 nm. The measured receiver sensitivities at 5, 3.125, 2, and 1 Gb/s, were -10.9, -15.4, -16.5, and -19 dBm, respectively. A 3-V single-supply operation was possible at bit rates up to 3.125 Gb/s. The transimpedance gain of the receivers was in the range 53.4-31 dB/spl Omega/. The circuit dissipated total power between 10 mW and 35 mW, depending on the design.
TL;DR: In this article, a solar blind metal-semiconductor-metal detectors have been fabricated based on AlGaN grown on Si by molecular-beam epitaxy, and submicron finger spacings were obtained by electron-beam lithography, and demonstrated a significant improvement of the responsivity and spectral selectivity.
Abstract: Solar blind metal–semiconductor–metal detectors have been fabricated based on AlGaN grown on Si by molecular-beam epitaxy. Submicron finger spacings were obtained by electron-beam lithography, and allowed us to demonstrate a significant improvement of the responsivity and the spectral selectivity. These results were explained by numerical two-dimensional calculations of the electric-field distribution. The simulation also explained the dependence of the response on applied bias.
TL;DR: In this paper, double-stage taper photodiodes (DSTPs) have been developed for 40-Gb/s applications with high efficiency, ultrawide band, high optical power handling capability, and low-cost module fabrication.
Abstract: The design, fabrication, and performance of double-stage taper photodiodes (DSTPs) are reported. The objective of this work is to develop devices compatible with 40-Gb/s applications. Such devices require high efficiency, ultrawide band, high optical power handling capability, and compatibility with low-cost module fabrication. The integration of mode size converters improves both the coupling efficiency and the responsivity with a large fiber mode diameter. Responsivity of 0.6 A/W and 0.45 A/W are achieved with a 6-/spl mu/m fiber mode diameter and cleaved fiber, respectively, providing relaxed alignment tolerances (/spl plusmn/1.6 /spl mu/m and /spl plusmn/2 /spl mu/m, respectively), compatible with cost-effective packaging techniques. DSTPs also offer a wide bandwidth greater than 40 GHz and transverse-electric/transverse-magnetic polarization dependence lower than 0.2 dB. Furthermore, a DSTP saturation current as high as 11 mA results in optical power handling greater than +10 dBm and a high output voltage of 0.8 V. These capabilities allow the photodiode to drive the decision circuit without the need of a broad-band electrical amplifier. The DSTP devices presented here demonstrate higher responsivities with large fiber mode diameter and better optical power handling capabilities and are compared with classical side-illuminated photodiodes.
TL;DR: In this paper, the authors describe the design, optimization and fabrication of side-illuminated p-i-n photodetectors, grown on InP substrate, suitable for surface hybrid integration in low-cost modules.
Abstract: We describe the design, optimization and fabrication of side-illuminated p-i-n photodetectors, grown on InP substrate, suitable for surface hybrid integration in low-cost modules. The targeted functionalities of these photodetectors were a very high responsivity at 1.3- and 1.55-/spl mu/m wavelengths and quasi-independent on the optical polarization, and had a high alignment tolerance. Moreover, in order to avoid any reliability problem, the principle of evanescent coupling was adopted. Two photodetectors were optimized, fabricated, and tested; the first was for classical cleaved fiber, and the second was for lensed fiber. Because the considered epitaxial structures were complicated to optimize, the method of the genetic algorithm was used, associated with a beam propagation method (BPM). The photodetectors are based on multimode diluted waveguides, which are promising structures in the field of optoelectronics and integrated optics. Starting from the presented comparisons between experimental and theoretical results, the interest of the design method is discussed and the complete performances of newly fabricated devices are presented. The aspect of the cutoff frequency is also considered.
TL;DR: In this article, the effect of accumulated charges at the InGaAs-InAlAs heterointerface was examined through a comparison of the dark currents of unpassivated photodors and photodiodes passivated with either polyimide or SiN/sub x/.
Abstract: High-speed metamorphic double heterojunction photodiodes were fabricated on GaAs substrates for long-wavelength optical fiber communications. The high quality linearly graded quaternary InGaAlAs metamorphic buffer layer made possible the growth of excellent InGaAs-InGaAlAs-InAlAs heterostructures on GaAs substrates. The use of a novel double heterostructure employing an InGaAlAs optical impedance matching layer, a chirped InGaAs-InAlAs superlattice graded bandgap layer (SL-GBL), and a large bandgap i-InAlAs drift region enabled photodiodes to achieve a low dark current of 500 pA, a responsivity of 0.6 A/W, and a -3 dB bandwidth of 38 GHz at -5 V reverse bias for 1.55 /spl mu/m light. The effect of accumulated charges at the InGaAs-InAlAs heterointerface was examined through a comparison of the dark currents of InGaAs-InAlAs and InGaAs-InP abrupt single heterojunction photodiodes; to photodiodes with chirped InGaAs-InAlAs SL-GBLs. The charge accumulation effects observed in abrupt heterojunction devices were suppressed by including a chirped InGaAs-InAlAs SL-GBL between the InGaAs absorption layer and InAlAs drift layer. The effect of passivation techniques was evaluated by comparing dark currents of unpassivated photodiodes and photodiodes passivated with either polyimide or SiN/sub x/. The enhancement of photodiode bandwidth through the inclusion of a transparent large bandgap I-InAlAs drift region was verified by comparing the bandwidths of the P-i-I-N photodiodes that have I-InAlAs between i-InGaAs photoabsorption layer and N/sup +/ InAlAs cathode to conventional P-i-N photodiodes without a drift region.
21 May 2002
TL;DR: In this paper, the authors compared the performance of the p-i-n photodiodes with different widths for the depletion region, which shows a trade-off between speed and responsivity of the devices.
Abstract: Thanks to advances in the quality of wide bandgap AlxGa1-xN semiconductors, these materials have emerged as the most promising approach for the realization of photon detectors operating in the near ultraviolet from 200 to 365 nm. This has in turn spurred the need for such devices in an increasing number of applications ranging from water purification to early missile threat warning systems. Nevertheless, the control of the material quality and doping, and the device technology remain tremendous challenges in the quest for the realization of high performance photodetectors. Design of the photodetector structure is one of the key issues in obtaining high performance devices; especially the thickness of the intrinsic region for p-i-n photodiodes is a crucial value and needs to be optimized. We compare the performance of the p-i-n photodiodes with different widths for the depletion region, which shows a trade-off between speed and responsivity of the devices. Furthermore, another challenge at present is the realization of low resistivity wide bandgap p-type AlxGa1-xN semiconductors. We present here recent advances and propose future research efforts in the enhancement of the AlxGa1-xN p-type conductivity through the use of polarization fields in AlxGa1-xN/GaN superlattice structures.
08 Dec 2002
TL;DR: In this paper, a PIN photodiode combining high responsivity, fast response and low capacitance in BiCMOS technology is presented, having no verifiable influence on the transistor parameters.
Abstract: We attain a PIN photodiode combining high responsivity, fast response and low capacitance in BiCMOS technology. Only a slight process modification, having no verifiable influence on the transistor parameters is necessary. We achieve bandwidths of 625 MHz and 240 MHz at 670 and 780 nm as well as a quantum efficiency of 96.5%.
TL;DR: The large photovoltage developed across a layer of selectively deposited bacteriorhodopsin is applied to the gate terminal of a monolithically integrated GaAs-based modulation-doped field-effect transistor, which delivers an amplified photoinduced current signal.
Abstract: We have applied the large photovoltage developed across a layer of selectively deposited bacteriorhodopsin to the gate terminal of a monolithically integrated GaAs-based modulation-doped field-effect transistor, which delivers an amplified photoinduced current signal. The integrated biophotoreceiver device exhibits a responsivity of 3.8 A/W. The optoelectronic integrated circuit is achieved by molecular-beam epitaxy of the field-effect transistor's heterostructure, photolithography, and selective-area bacteriorhodopsin electrodeposition.
TL;DR: In this paper, ten stacked self-assembled InAs/GaAs quantum dot infrared photodetectors (QDIP) with different Al/sub 0.3/Ga/Sub 0.7/As barrier widths and growth temperatures were prepared.
Abstract: The ten stacked self-assembled InAs/GaAs quantum dot infrared photodetectors (QDIP) with different Al/sub 0.3/Ga/sub 0.7/As barrier widths and growth temperatures were prepared. Asymmetric current-voltage (I-V) characteristics and 2/spl sim/7.5 /spl mu/m detection window were observed. Peak responsivity of 84 mA/W at -0.4 V and peak specific detectivity of 2.5/spl times/10/sup 9/ cm-Hz/sup 1/2//W at zero bias were observed at 50 K. The characteristics of polarization insensitivity over the incident light and the high background photocurrent suggest that the self-assembled QDIP can be operated at higher temperature (/spl sim/250 K) under normal incidence condition in contrast to quantum well infrared photodetector (QWIP).