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1

Van der Waals materials for HOT infrared detectors : a review

Rogalski Antoni

Opto-Electronics Review

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2022

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Vol. 30, No. 1

art. no. e140551

EN

In the last decade several papers have announced usefulness of two-dimensional materials for high operating temperature photodetectors covering long wavelength infrared spectral region. Transition metal dichalcogenide photodetectors, such as PdSe₂/MoS₂ and WS₂/HfS₂ heterojunctions, have been shown to achieve record detectivities at room temperature (higher than HgCdTe photodiodes). Under these circumstances, it is reasonable to consider the advantages and disadvantages of two-dimensional materials for infrared detection. This review attempts to answer the question thus posed.

2

Corrigendum to “Van der Waals materials for HOT infrared detectors : a review” [Opto-Electronics Review 30 (2022) e140551]

Rogalski Antoni

Opto-Electronics Review

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2022

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Vol. 30, No. 2

art. no. e141441

3

Comparison of performance limits of HOT HgCdTe photodiodes with 2D material infrared photodetectors

Rogalski Antoni, Kopytko Małgorzata, Martyniuk Piotr, Hu Weida

Opto-Electronics Review

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2020

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Vol. 28, No. 2

82--92

EN

The semiempirical rule, “Rule 07” specified in 2007 for P-on-n HgCdTe photodiodes has become widely popular within infrared community as a reference for other technologies, notably for III-V barrier photodetectors and type-II superlattice photodiodes. However, in the last decade in several papers it has been shown that the measured dark current density of HgCdTe photodiodes is considerably lower than predicted by benchmark Rule 07. Our theoretical estimates carried out in this paper support experimental data. Graphene and other 2D materials, due to their extraordinary and unusual electronic and optical properties, are promising candidates for high-operating temperature infrared photodetectors. In the paper their room-temperature performance is compared with that estimated for depleted P i-N HgCdTe photodiodes. Two important conclusions result from our considerations: the first one, the performance of 2D materials is lower in comparison with traditional detectors existing on global market (InGaAs, HgCdTe and type- II superlattices), and the second one, the presented estimates provide further encouragement for achieving low-cost and high performance HgCdTe focal plane arrays operating in high-operating temperature conditions.

4

2D material infrared and terahertz detectors : status and outlook

Rogalski Antoni, Kopytko Małgorzata, Martyniuk Piotr

Opto-Electronics Review

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2020

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Vol. 28, No. 3

107--154

EN

Graphene applications in electronic and optoelectronic devices have been thoroughly and intensively studied since graphene discovery. Thanks to the exceptional electronic and optical properties of graphene and other two-dimensional (2D) materials, they can become promising candidates for infrared and terahertz photodetectors. Quantity of the published papers devoted to 2D materials as sensors is huge. However, authors of these papers address them mainly to researches involved in investigations of 2D materials. In the present paper this topic is treated comprehensively with including both theoretical estimations and many experimental data. At the beginning fundamental properties and performance of graphene-based, as well as alternative 2D materials have been shortly described. Next, the position of 2D material detectors is considered in confrontation with the present stage of infrared and terahertz detectors offered on global market. A new benchmark, so-called “Law 19”, used for prediction of background limited HgCdTe photodiodes operated at near room temperature, is introduced. This law is next treated as the reference for alternative 2D material technologies. The performance comparison concerns the detector responsivity, detectivity and response time. Place of 2D material-based detectors in the near future in a wide infrared detector family is predicted in the final conclusions.

5

Comparison of performance limits of the HOT HgCdTe photodiodes with colloidal quantum dot infrared detectors

Rogalski A., Kopytko M., Martyniuk P., Hu W.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2020

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Vol. 68, nr 4

845--855

EN

In the past decade, there has been significant progress in development of the colloidal quantum dot (CQD) photodetectors. The QCD’s potential advantages include: cheap and easy fabrications, size-tuneable across wide infrared spectral region, and direct coating on silicon electronics for imaging, which potentially reduces array cost and offers new modifications like flexible infrared detectors. The performance of CQD high operating temperature (HOT) photodetectors is lower in comparison with detectors traditionally available on the global market (InGaAs, HgCdTe and type-II superlattices). In several papers their performance is compared with the semiempirical rule, “Rule 07” (specified in 2007) for P-on-n HgCdTe photodiodes. However, at present stage of technology, the fully-depleted background limited HgCdTe photodiodes can achieve the level of room-temperature dark current considerably lower than predicted by Rule 07. In this paper, the performance of HOT CQD photodetectors is compared with that predicted for depleted P-i-N HgCdTe photodiodes. Theoretical estimations are collated with experimental data for both HgCdTe photodiodes and CQD detectors. The presented estimates provide further encouragement for achieving low-cost and high performance MWIR and LWIR HgCdTe focal plane arrays operating in HOT conditions.

6

New material systems for third generation infrared photodetectors

Rogalski A.

Opto-Electronics Review

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2008

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Vol. 16, No. 4

458-482

EN

Third-generation infrared (IR) systems are being developed nowadays. In the common understanding, these systems provide enhanced capabilities-like larger numbers of pixels, higher frame rates, and better thermal resolution as well as multicolour functionality and other on-chip functions. In this class of detectors, two main competitors, HgCdTe photodiodes and quantum-well photoconductors, have being developed. Recently, two new material systems have been emerged as the candidates for third generation IR detectors, type II InAs/GaInSb strain layer superlattices (SLSs) and quantum dot IR photodetectors (QDIPs). In the paper, issue associated with the development and exploitation of multispectral photodetectors from these new materials is discussed. Discussions is focused on most recently on-going detector technology efforts in fabrication both photodetectors and focal plane arrays (FPAs). The challenges facing multicolour devices concerning complicated device structures, multilayer material growth, and device fabrication are described.

7

Third generation infrared detectors

Rogalski A.

Elektronika : konstrukcje, technologie, zastosowania

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2006

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Vol. 47, nr 3

19-27

EN

Hitherto, two families of multielement infrared (IR) detectors are used for principal military and civilian infrared applications; one is used for scanning systems (first generation) and the other is used for staring systems (second generation). Third generation systems are being developed nowadays. In the common understanding, third generation IR systems provide enhanced capabilities like larger number of pixels, higher frame rates, better thermal resolution as well as multicolour functionality and other on-chip functions. In the paper, issues associated with the development and exploitation of third generation infrared photon detectors are discussed. In this class of detectors two main competitors, HgCdTe photodiodes and quantum well photoconductors are considered. The performance figures of merit of state-of-the-art QWIP and HgCdTe FPA's are similar because the main limitations come from the readout circuits. However, in the long wavelength infrared (LWIR) region, the HgCdTe material fail to give the requirements of large format two-dimensional (2D) arrays due to metallurgical problems of the epitaxial layers such as uniformity and number of defected elements.

PL

Dotychczas w technice podczerwieni stosowane są dwojakiego rodzaju wieloelementowe detektory podczerwieni: linijki detektorów w systemach ze skanowaniem mechanicznym (zwanych również systemami 1. generacji) i dwuwymiarowe matryce detektorów w systemach ze skanowaniem elektronicznym (zwanych systemami 2. generacji). Trzecia generacja systemów jest rozwijana obecnie i jak dotychczas jej definicja nie jest precyzyjnie określona. Zakłada się, że powinna mieć większąliczbę pikseli obrazowych, charakteryzować się większąszybkościąodczytu ramki obrazu, lepszą rozdzielczością temperaturową, możliwością wielospektralnej analizy obrazu w różnych zakresach widmowych oraz mieć inne dodatkowe on-line funkcje. W artykule przedstawiono aktualny stan zaawansowania prac w zakresie koncepcji realizacji wyżej określonych funkcji i technologicznych problemów praktycznej implementacji detektorów trzeciej generacji. Dotychczas rozważano dwie grupy materiałów jako najbardziej perspektywicznych w osiągnięciu zamierzonych celów: roztwór stały HgCdTe i supersieci AlGaAs/GaAs. Osiągi matryc wykonywanych z tych dwóch półprzewodników są podobne z tej głównej przyczyny, że są ograniczone typowymi pojemnościami wejściowymi krzemowych procesorów odczytu sygnałów, rzędu 10⁷ elektronów.

8

Generation-recombination effects in high temperature HgCdTe heterostructure photodiodes

Jóźwikowska A., Jóźwikowski K., Rutkowski J., Orman Z., Rogalski A.

Opto-Electronics Review

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2004

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Vol. 12, No. 4

417-428

EN

The effect of built-in electric fields and misfit dislocations on dark currents in high temperature MOCVD HgCdTe infrared heterostructure photodiodes has been investigated. From experimental data results that the current-voltage characteristics at 240 K and 300 K indicate significant contributions from tunnelling effects, which dominate the leakage current mechanism for reverse bias greater than a few tens of milivolts. Standard theoretical models show that Auger generation-recombination processes determine dark current in high temperature HgCdTe photodiodes. But taking into account only Auger mechanisms much overestimated theoretical results are obtained. To explain this fact, a two-dimensional model has been developed to investigate the dark current mechanisms in the vicinity of the junction termination at built-in electric fields. Calculated profiles of the energy bands and electric field along different cross-sections of the photodiode indicate that the electric field achieves a maximum value of the order of mid 10⁵ V/cm in the area the junction termination at the HgCdTe heterointerface. In these regions the high density of misfit dislocations are observed too. The presence of high electric field in this area decreases the ionisation energies of trap levels located in region of dislocations core, and hence increases the efficiency of Shockley-Read-Hall generation-recombination process. In addition to diffusion, generation-recombination and trap assisted tunnelling mechanisms, our model include the Poole-Frankel and phonon-trap assisted tunnelling effects in calculations of dynamic resistance of the junctions. The best fit of experimental data with theoretical predictions for dynamic resistance versus temperature has been obtained for dislocation density in the bulk of HgCdTe layer equal to 5x10⁻⁷ cm⁻².

9

Status of HgCdTe photodiodes at the Military University of Technology

Kubiak L., Madejczyk P., Wenus J., Gawron W., Jóźwikowski K., Rutkowski J., Rogalski A.

Opto-Electronics Review

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2003

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Vol. 11, No. 3

211-226

EN

The paper presents technological achievements in fabrication of cryogenically-cooled and ambient temperature HgCdTe photodiodes carried out during the last four years at the Institute of Applied Physics, Military University of Technology. Because of the complicated and expensive fabrication process, numerical simulation has become a critical tool for the development of HgCdTe bandgap engineering devices. Therefore in the second part of the paper, an original interation scheme is used to predict the effect of composition and doping profiles on the heterojunction detector parameters. A novel tipping boat for liquid phase epitaxial (LPE) growth of HgCdTe from Te-rich solutions has been proposed. The successful fabrication of long wevelength infrared (LWIR) Hg1-yCdyTe/Hg1-xCdxTe heterostructures (y x) on semi-insulating (111)CdZnTe substrates is presented. The performance of p-on-n double-layer heterojunction (DLHJ) photodiodes at temperature 77 K is analysed. It is also shown that LPE can be used to realise advanced bandgap engineered multi-junction structures. The parameters and characteristics of the new type of HgCdTe buried photodiodes, operated at near-room temperature (T = 200-300 K) in LWIR spectral range, are reported. Finally, an effective numerical model for performance predictions of HgCdTe heterostructure device is presented. The model is used to analyse the performance of dual-band HgCdTe photovoltaic detector and mid wavelength infrared (MWIR) HgCdTe heterostructure device. In the last case, it is shown that excess 1/f noise of MWIR non-equilibrium heterostructure device is connected with fluctuation of carrier mobility.

10

Analysis of VLWIR HgCdTe photodiode performance

Wenus J., Rutkowski J., Rogalski A.

Opto-Electronics Review

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2003

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Vol. 11, No. 2

143-149

EN

The performance of very long wavelength infrared (VLWIR) HgCdTe photodiodes at temperatures ranging from 77 K up to 150 K is presented. The effect of inherent and excess current mechanisms on quantum efficiency and dynamic resistance-area RA product is analysed. Different methods of determining the ideality factor are shown and among them the one based on the use of RA product versus bias voltage proves to be most reliable. At higher temperatures, however, the calculated ideality factor does not give any useful information about the nature of the p-n junction current due to significant influence of the series and shunt resistances. A comparison of the experimental data with the results of analytical and numerical calculations shows that the photodiodes with cut-off wavelength up to 14.5 um are diffusion-limited at temperatures exceeding 100K.

11

Materials and process issues in the fabrication of high performance VLWIR HgCdTe infrared detectors

Vydyanath H. R., Nathan V.

Opto-Electronics Review

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2001

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Vol. 9, No. 1

1-5

EN

Issues relating to fabrication of VLWIR HgCdTe detectors with high performance and uniformity are reviewed. The primary mechanism operative in the activation of p type dopants in HgCdTe is discussed along with implications for fabrication of high performance detectors. Origin of native defect related deep centres in limiting the minority carrier lifetime is explored.

12

Inherent and additional limitations of HgCdTe heterojunction photodiodes

Rutkowski J., Wenus J.

Opto-Electronics Review

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2001

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Vol. 9, No. 3

331-335

EN

The performance of P-on-n double-layer heterojunction (DLHJ) HgCdTe photodiodes at temperature of 77 K is presented. The effect of inherent and excess current mechanisms on quantum efficiency and R₀A product is analysed. The diodes with good R₀A operability, high quantum efficiency, and low 1/f noise have been demonstrated at cutoff wavelengths up to 14 mm. The experimental results show that proper surface passivation and low series/ contact resistance are major issues relating to fabrication of HgCdTe detectors with high performance.

13

MCT sensor readout devices with charge current injection and preliminary signal treatment : testing procedure

Sizov F. F., Derkach Y. P., Reva V. P., Kononenko Y. G.

Opto-Electronics Review

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1999

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Vol. 7, No. 4

327-338

EN

Silicon read-out devices with input direct injection and buffered direct injection circuits and charge coupled devices (CCD) multiplexers to be used with n+ -p photovoltaic (PV) multielement arrays were designed, manufactured, and tested at T=77-300 K. Into these readout devices testing switches were incorporated which attach the sources of direct injection transistors to the common load resistors to imitate the output signal of mercury cadmium telluride (MCT) photodiodes. The silicon readout devices for 2x4x128(144) arrays [two sets of 128 or 144 lines (channels) with four pixels in row] in which time delay and integration (TDI) is performed with skimming and partitioning functions, were manufactured by n-channel MOS technology with buried channel CCD register. The designed CCD readout devices are driven with four- or two-phase clock pulses. The amount of charge, which can be stored in the readout device, depends on the mode used. Without skimming and partitioning modes it is 2.4 pC per channel at an output signal of about 5V. With partitioning mode included it is about 6.4 pC, and it is about 10.0 pC with skimming and partition\ing modes switched on. Different operating modes depending on the application purposes can be selected taking into account programmable integration time, possible operation with and without TDI function, availability of skimming level and partitioning factor, etc.