Sensitivity Limit of Nanoscale Phototransistors

Rezaei, Mohsen; Park, Minsu; Tan, Chee Leong; Mohseni, Hooman

doi:10.1109/led.2017.2721381

Cited by 18 publications

(21 citation statements)

References 21 publications

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“…The measured I D is the external dark current, which can be obtained by multiplying the internal dark current by the optical gain. 29,30 Therefore, the increased optical gain caused by the passivation results in the increased I D . The optical gain of HPTs is defined as G opt ¼ hDI c /qP in , where h is the energy of an incident photon and DI c is the difference between collector photocurrent (I P ) and I D .…”

Section: Resultsmentioning

confidence: 99%

Surface passivation and aging of InGaAs/InP heterojunction phototransistors

Park

Razaei

Barnhart

et al. 2017

Journal of Applied Physics

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We report the effect of different surface treatment and passivation techniques on the stability of InGaAs/InP heterojunction phototransistors (HPTs). An In 0.53 Ga 0.47 As surface passivated with aqueous ammonium sulfide ((NH 4) 2 S), aluminum oxide (Al 2 O 3) grown by atomic layer deposition (ALD), and their combination is evaluated by using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). All samples were kept in the air ambient, and their performances were periodically measured to investigate their long-term stability. Raman spectroscopy revealed that the peak intensity of the GaAs-like longitudinal optical phonon of all passivated samples is decreased compared with that of the control sample. This is attributable to the diminution of the carriers near the passivated surfaces, which was proven by extracted surface potential (V s). The V s of all passivated samples was decreased to less than half of that for the control sample. XPS evaluation of As3d spectra showed that arsenic oxides (As 2 O 3 and As 2 O 5) on the surfaces of the samples can be removed by passivation. However, both Raman and XPS spectra show that the (NH 4) 2 S passivated sample reverts back over time and will resemble the untreated control sample. When capped with ALD-grown Al 2 O 3 , passivated samples irrespective of the pretreatment show no degradation over the measured time of 4 weeks. Similar conclusions are made from our experimental measurement of the performance of differently passivated HPTs. The ALD-grown Al 2 O 3 passivated devices show an improved optical gain at low optical powers and long-term stability. Published by AIP Publishing.

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Section: Resultsmentioning

confidence: 99%

Surface passivation and aging of InGaAs/InP heterojunction phototransistors

Park

Razaei

Barnhart

et al. 2017

Journal of Applied Physics

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“…In its typical low-voltage operating conditions, the amplification mechanism of EI detectors is based on transistor action: namely the modulation of a potential barrier by trapped photo-generated excess carriers [37,38]. However, it has been observed that when the EI detectors are biased to higher voltage, a high enough field is created at the heterojunction to trigger Geiger-like operation [39,40].…”

Section: Programmable Operating Modes For An Electron-injection Sensormentioning

confidence: 99%

Dynamically Reconfigurable Data Readout of Pixel Detectors for Automatic Synchronization with Data Acquisition Systems

Fahim

Bianconi

Rabinowitz

et al. 2020

Sensors

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Reconfigurable detectors with dynamically selectable sensing and readout modes are highly desirable for implementing edge computing as well as enabling advanced imaging techniques such as foveation. The concept of a camera system capable of simultaneous passive imaging and dynamic ranging in different regions of the detector is presented. Such an adaptive-autonomous detector with both spatial and temporal control requires programmable window of exposure (time frames), ability to switch between readout modes such as full-frame imaging and zero-suppressed data, modification of the number of pixel data bits and independent programmability for distinct detector regions. In this work, a method is presented for seamlessly changing time frames and readout modes without data corruption while still ensuring that the data acquisition system (DAQ) does not need to stop and resynchronize at each change of setting, thus avoiding significant dead time. Data throughput is maximized by using a minimum unique data format, rather than lengthy frame headers, to differentiate between consecutive frames. A data control and transmitter (DCT) synchronizes data transfer from the pixel to the periphery, reconfigures the data to transmit it serially off-chip, while providing optimized decision support based on a DAQ definable mode. Measurements on a test structure demonstrate that the DCT can operate at 1 GHz in a 65 nm LP CMOS process.

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“…Electrical functionalization of Al 2 O 3 via reliable and spatially-accurate control of its conductivity could enable novel sensing technologies encompassing electrical contacts embedded in a mechanically hard, chemically inert, and electrically insulating dielectric matrix. Examples of such technological applications include photon emission and detection 7,[16][17][18][19] , low-energy in-terconnects [20][21][22] , energy conversion 1,23,24 , and implantable devices [25][26][27] . We here present an effective method for the non-subtractive nanopatterning of electrically conductive wires and other features embedded in a dielectric Al 2 O 3 substrate, using focused ion beam (FIB).…”

Section: Thin Films | Alumina | Dielectrics | Defect Engineering | Co...mentioning

confidence: 99%

Giant Conductivity Modulation of Aluminum Oxide Using Focused Ion Beam

Bianconi¹,

Park²,

Mohseni

2019

ACS Appl. Electron. Mater.

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Precise control of the conductivity of semiconductors through doping has enabled the creation of advanced electronic devices, similarly, the ability to control the conductivity in oxides can enable novel advanced electronic and optoelectronic functionalities. While this was successfully shown for moderately insulating oxides, such as In 2 O 3 , a reliable method for increasing the conductivity of highly insulating, wide bandgap dielectrics, such as aluminum oxide (Al 2 O 3 ), has not been reported yet. Al 2 O 3 is a material of significant technological interest, permeating diverse fields of application, thanks to its exceptional mechanical strength and dielectric properties. Here we present a versatile method for precisely changing the conductivity of Al 2 O 3 . Our approach greatly exceeds the magnitude of the best previously reported change of conductivity in an oxide (In 2 O 3 ). With an increase in conductivity of about 14 orders of magnitude, our method presents about 10 orders of magnitude higher change in conductivity than the best previously reported result. Our method can use focused ion beam to produce conductive zones with nanoscale resolution within the insulating Al 2 O 3 matrix. We investigated the source of conductivity modulation and identified trap-assisted conduction in the ion damage-induced defects as the main charge transport mechanism. Temperature-dependency of the conductivity and optical characterization of the patterned areas offer further insight into the nature of the conduction mechanism. We also show that the process is extremely reproducible and robust against moderate annealing temperatures and chemical environment. The record conductivity modulation, combined with the nanoscale patterning precision allows the creation of conductive zones within a highly insulating, mechanically hard, chemically inert, and bio-compatible matrix, which could find broad applications in electronics, optoelectronics, and medical implants.Aluminum oxide (Al 2 O 3 ) is one of the most widely employed dielectric materials, thanks to its excellent insulating properties 1 , mechanical hardness and resistance 2 , and biocompatibility 2,3 , with applications ranging from device passivation 1,4-8 , MOSFET gate 9-13 , to biomedical implants and antifouling passivation 2,3,14,15 . Electrical functionalization of Al 2 O 3 via reliable and spatially-accurate control of its conductivity could enable novel sensing technologies encompassing electrical contacts embedded in a mechanically hard, chemically inert, and electrically insulating dielectric matrix. Examples of such technological applications include photon emission and detection 7,16-19 , low-energy in-terconnects 20-22 , energy conversion 1,23,24 , and implantable devices [25][26][27] . We here present an effective method for the non-subtractive nanopatterning of electrically conductive wires and other features embedded in a dielectric Al 2 O 3 substrate, using focused ion beam (FIB). While patterning of nanowires in transparent conductive In 2 O 3 has been ...

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Sensitivity Limit of Nanoscale Phototransistors

Cited by 18 publications

References 21 publications

Surface passivation and aging of InGaAs/InP heterojunction phototransistors

Surface passivation and aging of InGaAs/InP heterojunction phototransistors

Dynamically Reconfigurable Data Readout of Pixel Detectors for Automatic Synchronization with Data Acquisition Systems

Giant Conductivity Modulation of Aluminum Oxide Using Focused Ion Beam

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