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1

High-operating temperature MWIR nBn HgCdTe detector grown by MOCVD

Kopytko M., Kębłowski A., Gawron W., Madejczyk P., Kowalewski A, Jóźwikowski K

Opto-Electronics Review

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2013

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Vol. 21, No. 4

402-405

EN

The paper reports on the first experimental results of the mid-wave infrared (MWIR) HgCdTe barrier detectors operated at near-room temperatures and fabricated using metal organic chemical vapor deposition (MOCVD). SIMS profiles let to compare projected and obtained structures and reveals interdiffusion processes between the layers. Undesirable iodine diffusion from cap to the barrier increase the valance band offset and is the key item in limiting the performance of HgCdTe nBn detector. However, MOCVD technology with a wide range of composition and donor/acceptor doping and without post grown annealing might be successfully adopted for barrier device architectures.

2

Zjawiska fotoelektryczne w złożonych heterostruturach HgCdTe stosowanych w konstrukcjach niechłodzonych detektorów podczerwieni

Gawron W., Rogalski A.

Elektronika : konstrukcje, technologie, zastosowania

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2011

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Vol. 52, nr 10

28-31

PL

Artykuł przedstawia wybrane wyniki prac badawczych nad udoskonaleniem konstrukcji niechłodzonych detektorów podczerwieni z warstw epiaksjalnych HgCdTe uzyskiwanych w technologii MOCVD na podłożu GaAs. Badania te zrealizowano w Instytucie Fizyki Technicznej Wojskowej Akademii Technicznej w ramach realizacji zadania nr 6 grantu zamawianego PBZ - MNiSW 02/I/2007.

EN

The paper presents selected results of studies connected with development of uncooled HgCdTe infrared detectors fabricated using MOCVD epitaxial deposition on GaAs substrates. This paper has been done in Institute of Applied Physics Military University of Technology under financial support of the Polish Ministry of Sciences and Higher Education, Key Project PBZ - MNiSW 02/I/2007.

3

Niechłodzone detektory podczerwieni z HgCdTe

Pawluczyk J., Piotrowski J., Gawron W.

Elektronika : konstrukcje, technologie, zastosowania

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2011

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Vol. 52, nr 10

54-56

PL

Artykuł prezentuje wyniki badań nad rozwojem niechłodzonych detektorów podczerwieni, zrealizowanych w VIGO System SA w ramach realizacji zadania nr 5 pt. "Niechłodzone detektory podczerwieni z HgCdTe", grantu zamawianego PBZ - MNiSW 02/I/2007 pt.: "Zaawansowane technologie dla półprzewodnikowej optoelektroniki podczerwieni". Niechłodzone detektory podczerwieni z HgCdTe to jeden z niewielu produktów optoelektronicznych produkowanych obecnie w Polsce i eksportowanych do wielu krajów świata. Przyrządy te znajdują zastosowania praktyczne w nowoczesnej aparaturze naukowej i medycznej, w przemyśle, ochronie środowiska naturalnego, technice wojskowej.

EN

Uncooled infrared photodetectors made from HgCdTe are one of few optoelectronic products manufactured currently in Poland and exported to many countries worldwide. The devices have found important applications for scientific and medical instruments, in industry, environment protection and military technique. The paper presents the current state of the art in the field of uncooled HgCdTe photodetectors in Poland. This paper has been done in VIGO System SA under financial support of the Polish Ministry of Sciences and Higher Education, Key Project PBZ - MNiSW 02/I/2007.

4

Control of acceptor doping in MOCVD HgCdTe epilayers

Madejczyk P., Piotrowski A., Kłos K., Gawron W., Rutkowski J., Rogalski A.

Opto-Electronics Review

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2010

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Vol. 18, No. 3

271-276

EN

The acceptor doping of mercury cadmium telluride (HgCdTe) layers grown by MOCVD are investigated. (111)HgCdTe layers were grown on (100)GaAs substrates at 350°C using horizontal reactor and interdiffused multilayer process (IMP). TDMAAs and AsH3 were alternatively used as effective p-type doping precursors. Incorporation and activation rates of arsenic have been studied. Over a wide range of Hg₁₋xCdxTe compositions (0.17 < x < 0.4), arsenic doping concentration in the range from 5×10¹⁵ cm⁻³ to 5×10¹⁷ cm⁻³ was obtained without postgrowth annealing. The electrical and chemical properties of epitaxial layers are specified by measurements of SIMS profiles, Hall effect and minority carrier lifetimes. It is confirmed that the Auger-7 mechanism has decisive influence on carrier lifetime in p-type HgCdTe epilayers.

5

Two-colour HgCdTe infrared detectors operating above 200 K

Rutkowski J., Madejczyk P., Piotrowski A., Gawron W., Jóźwikowski K., Rogalski A.

Opto-Electronics Review

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2008

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Vol. 16, No. 3

321-327

EN

The performance of dual waveband HgCdTe photodiodes fabricated using metaloorganic chemical vapour deposition operated at high temperatures is presented. The effect of additional separating layer on the quantum efficiency and cross-talk of the photodiodes is analyzed. The photodiodes with cutoff wavelengths up to 6 um, good RoA product, and high quantum efficiency at 200 K have been demonstrated. The temperature dependence of the differential resistance is discussed. It is shown that the multilayer heterojunction P-n-N-n-P structure operating in a simultaneous mode has better performance than a structure operating in a sequential mode.

6

Growth and properties of MOCVD HgCdTe epilayers on GaAs substrates

Madejczyk P., Piotrowski A., Gawron W., Kłos K., Pawluczyk J., Rutkowski J., Piotrowski J., Rogalski A.

Opto-Electronics Review

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2005

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Vol. 13, No. 3

239-251

EN

Growth of MOCVD Hg1-xCdxTe (HgCdTe) epilayers on GaAs substrates is described. The paper focuses on the interdiffused multilayer process (IMP). In this process, the CdTe/HgTe growth times are comparable with transition times between the phases. The non-optimum flow velocities and partial pressures that may induce poor morphology and reduce growth rate characterize the growth during transition stages. The optimum conditions for the growth of single layers and complex multilayer heterostructures have been established. One of the crucial stages of HgCdTe epitaxy is CdTe nucleation on GaAs substrate. Successful composite substrates have been obtained with suitable substrate preparation, liner and susceptor treatment, proper control of background fluxes and appropriate nucleation conditions. Due to the large mismatch between GaAs and CdTe, both (100) and (111) growth may occur. It mostly depends on substrate disorientation and preparation, nucleation conditions and growth temperature. Cd or Te substrate treatment just before growth results in (100) and (111) orientation, respectively. Generally, layers with orientation (100) show superior morphology compared to (111) but they are also characterized by hillocks. The benefits of the precursors ethyl iodine (EI) and arsine (AsH3) for controlled iodine donor doping and arsenic acceptor doping are summarized. Suitable growth conditions and post growth anneal is essential for stable and reproducible doping. In-situ anneal seems to be sufficient for iodine doping at any required level. In contrast, efficient As doping with near 100% activation requires ex-situ anneal at near saturated mercury vapours. The transport properties of HgCdTe epilayers indicate on achieving device quality material. Reproducible n- and p-type doping at the low, intermediate and high level (1015-1018 cm-3) has been achieved with stable iodine and arsenic dopants. The mobilities and carrier lifetimes achieved for extrinsically doped n-type and p-type layers follow essentially the same trends observed in state-of-the-art liquid phase epitaxy grown HgCdTe.

7

Growth of MOCVD HgCdTe heterostructures for uncooled infrared photodetectors

Piotrowski A., Madejczyk P., Gawron W., Kłos K., Pawluczyk J., Grudzień M., Piotrowski J., Rogalski A.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2005

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Vol. 53, nr 2

139-149

EN

In the paper recent progress at VIGO/MUT (Military University of Technology) MOCVD Laboratory in the growth of Hg1-xCdx Te (HgCdTe) multilayer heterostructures on GaAs/CdTe substrates is presented. The optimum conditions for the growth of single layers and complex multilayer heterostructures have been established. One of the crucial stages of HgCdTe epitaxy is CdTe nucleation on GaAs substrate. Successful composite substrates have been obtained with suitable substrate preparation, liner and susceptor treatment, proper control of background fluxes and appropriate nucleation conditions. The other critical stage is the interdiffused multilayer process (IMP). The growth of device-quality HgCdTe heterostructures requires complete homogenization of CdTe-HgTe pairs preserving at the same time suitable sharpness of composition and doping profiles. This requires for IMP pairs to be very thin and grown in a short time. Arsenic and iodine have been used for acceptor and donor doping. Suitable growth conditions and post growth anneal is essential for stable and reproducible doping. In situ anneal seems to be sufficient for iodine doping at any required level. In contrast, efficient As doping with near 100% activation requires ex situ anneal at near saturated mercury vapours. As a result we are able to grow multilayer fully doped (100) and (111) heterostructures for various infrared devices including photoconductors, photo electromagnetic and photovoltaic detectors. The present generation of uncooled long wavelength infrared devices is based on multijunction photovoltaic devices. The technology steps in fabrication of devices are described. It is shown that near-BLIP performance is possible to achieve at c.a 230 K with optical immersion. These devices are especially promising as 7.8-9.5-J-[mu]m detectors, indicating the potential for achieving detectivities above 10 do potęgi 9 cmHz1/2/W.

8

Uncooled operation of IR photodetectors

Piotrowski J.

Opto-Electronics Review

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2004

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Vol. 12, No. 1

111--122

EN

The ultimate performance of long wavelength infrared photodetectors operating at high temperatures is likely to be limited by the noise due to the statistical nature of thermal generation of charge carriers in narrow band gap semiconductors. Additional obstacles to achieve theoretical performance in practical devices arise from weak absorption of infrared radiation, short diffusion length of charge carriers in narrow gap semiconductors and other reasons. Various ways to improve performance of uncooled photodetector such as the reduction of thermal generation rate by proper selection of the semiconductor material, its doping and suppression of thermal generation by the non-equilibrium mode of operation are considered. Another possibility is the reduction of physical volume of a detector. This can be done by reducing a detector physical area and its thickness with appropriate means to preserve the device field of view and a quantum efficiency. The advanced architectures of uncooled Hg1-xCdxTe IR photoconductors, photoelectromagnetic and photovoltaic detector are described. The devices require heterostructures with complex band gap and doping profiles and can be grown by the low temperature epitaxial techniques. The most promising device for uncooled detection is heterojunction photodiode integrated with optical concentrator. The progress in technology of photodetectors will eventually lead to perfect and fast detection of long wavelength radiation without cooling.

9

MOCVD growth of Hg₁₋xCdxTe heterostructures for uncooled infrared photodetectors

Piotrowski A., Madejczyk P., Gawron W., Kłos K., Romanis M., Grudzień M., Piotrowski J., Rogalski A.

Opto-Electronics Review

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2004

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Vol. 12, No. 4

453-458

EN

We report here recent progress at VIGO/WAT MOCVD Laboratory in the growth of Hg₁₋xCdxTe (HgCdTe) multilayer heterostructures on GaAs/CdTe and other composite substrates for uncooled infrared photodetectors. The optimum conditions for the growth of single layers and complex multilayer heterostructures have been established. One of the crucial stages of the technology was CdTe nucleation on GaAs substrate. Successful composite substrates were obtained with suitable substrate preparation, liner and susceptor treatment, proper control of background fluxes and appropriate nucleation conditions. The other critical stage is the interdiffused multilayer process (IMP). The growth of device-quality HgCdTe heterostructures requires complete homogenization of CdTe-HgTe pairs preserving at the same time suitable sharpness of composition and doping profiles. This requires for IMP pairs to be very thin and grown in a short time. The practical implications for the IMP process are the CdTe/HgTe growth times that become comparable with transition times between the phases, characteristic for the MOCVD machine. The growth during transition stages is characterized by the non-optimum flow velocities and partial pressures that may induce poor morphology, reduce growth rate and cause other problems. This became especially acute for doped layers when large Cd/Te ratio is required for efficient incorporation and full activation of dopants. This has been solved by careful selection of hydrogen carrier gas and metaloorganics fluxes with suitable switching on and off times. Arsenic and iodine has been used for acceptor and donor doping. Suitable growth conditions and post growth anneal is essential for stable and reproducible doping. In-situ anneal seems to be sufficient for iodine doping at any required level. In contrast, efficient As doping with near 100% activation requires ex situ anneal at near saturated mercury vapors. As the result, we are able to grow multilayer fully doped (100) and (111) heterostructures for various infrared devices including photoconductors, photoelectromagnetic and photovoltaic detectors.