Amorphous Ge x Si 1-x and Ge x Si 1-x O y thin films for uncooled microbolometers

Metal-semiconductor contacts are a vital part of semiconductor devices as they can form a Schottky barrier or an Ohmic contact. The nature of the contact plays an important role in determining the electrical and physical characteristics of the device and hence is of paramount importance in the operation of the device. In the current work we report the design, fabrication, and current-voltage (I-V) characteristics of microbolometers, a type of infrared detector where the change in temperature changes the resistance of the sensing layer. Eight different types of microbolometers were fabricated using a-Si x Ge 1−x or a-Si x Ge 1−x O y sensing layers and Ti, Cr, Al, Au, Ni, or Ni 0.80 Cr 0.20 metals contacts. It has been observed that bolometers with an a-Si 0.15 Ge 0.85 (Si was lightly p-doped) sensing layer formed a Schottky contact with Ti, Au, Cr, and Al contact metals, while bolometers with a-Si 0.15 Ge 0.85 (Si was heavily n-doped) sensing layers formed an Ohmic contact with Au. For microbolometers with a Si 0.15 Ge 0.85 O 0.039 sensing layer, both Ni and Ni 0.80 Cr 0.20 contact metals formed the Ohmic contact. For a-Si x Ge 1−x and a-Si x Ge 1−x O y microbolometers, Au and Ni 0.80 Cr 0.20 were used as the absorber layers, respectively. The I-V characteristics of the microbolometers were analyzed with a thermionic emission model. A linear dependence on the Ge composition was approximated to find the effective Richardson constant. The theory predicts Richardson constants of 112 and 50 A/cm 2 K 2 for Si and Ge, respectively. Barrier heights of all devices are calculated and the reasons for the formation of the Ohmic and Schottky contacts are discussed. PACS No.: 07.57.Kp. Résumé : Les contacts metal-semiconducteur sont une partie vitale des dispositifs semiconducteurs, parce qu'ils peuvent former des barrières de Schottky ou des contacts ohmiques. La nature du contact est importante pour déterminer les propriétés électriques et physiques du dispositif et donc est d'une importance capitale dans l'opération du dispositif. Nous présentons ici le design, la fabrication et les caractéristiques courant-voltage (

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“…Table 1 shows the details of each of the devices used in this report. The details of the fabrication of devices are mentioned elsewhere [11,14].…”

Section: Methodsmentioning

confidence: 99%

Rectifying and Schottky characteristics of a-Si_xGe_1−xO_y with metal contacts

MuztobaMd

RanaMukti

2014

Can. J. Phys.

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“…Combining the properties of Ge (low bandgap energy, high mobility) and Si (abundance, stable, and easy-to-grow oxide) and mixing them with a low atomic composition of O 2 , Ge x Si 1– x O y has been used as one of the emerging materials for the sensing layer of microbolometer. Rana et al . used a-Ge x Si 1– x O y thin films sputtered from a Ge x Si 1– x target in an argon and oxygen environment.…”

Section: Materials Considerations For Wearable Bolometermentioning

confidence: 99%

“…h i b i t e d .microbolometer. Rana et al105 used a-Ge x Si 1−x O y thin films sputtered from a Ge x Si 1−x target in an argon and oxygen environment. In a parametric analysis of the effect of the electrooptical properties of the thin films on mixtures, they altered the atomic percentages of silicon and oxygen.…”

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confidence: 99%

Recent Developments in Wearable NEMS/MEMS-Based Smart Infrared Sensors for Healthcare Applications

Padha,

Yadav,

Dutta

et al. 2023

ACS Appl. Electron. Mater.

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Incorporating nano-and microelectromechanical systems (NEMS/MEMS)-based sensors in clothing and developing more compact and flexible devices have gained popularity recently. NEMS/MEMS-based bolometers/sensors have gained significance due to their high sensitivity and accuracy in measuring physical parameters such as temperature, humidity, pressure, and infrared (IR) and ultraviolet (UV) radiations. When worn on the body, bolometers can be employed in various applications such as environmental monitoring or health tracking. This review highlights the progress of smart wearable bolometers as NEMS/ MEMS-based sensors in the healthcare industry. Instead of visiting multiple healthcare facilities or devices, now people can assess their health status by measuring body temperature, sensing motion, respiratory functioning, blood pressure, oxygen levels of the blood, and heart functioning by integrating these devices into fabriclike garments, socks, shoe insoles, wrist watches, and other pieces of clothing. The article concludes by describing their varied challenges and possible solutions and prospects.

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“…They have measured under optimum conditions, a resistivity and a corresponding TCR of 10 k -cm and −5 %/K, respectively. A similar deposition method was performed by Rana and Butler [25]. In earlier work, they fixed a piece of silicon (cut from silicon wafer) to a Ge target and deposited using one power source, in later work they deposited Si 0.15 Ge 0.85 from one target in argon/oxygen environment [28].…”

Section: Introductionmentioning

confidence: 98%

Noise Reduction of Amorphous Si_xGe_yO_1–x–yThin Films for Uncooled Microbolometers by Si₃N₄Passivation and Annealing in Vacuum

et al. 2016

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This paper presents the fabrication and reduction of noise voltage power spectral density (PSD) of Si x Ge y O 1−x− y uncooled infrared microbolometers with four different compositions. The noise reduction was achieved by passivating Si x Ge y O 1−x− y with Si 3 N 4 layers and by annealing the devices in vacuum at 200°C, 250°C, or 300°C with different time intervals from 1 to 5 h. The voltage noise PSD was measured with a bias current between 0.07 and 0.6 µA before and after annealing. The lowest measured noise voltage PSD before annealing was on devices with Si 0.053 Ge 0.875 O 0.072 and Si 0.041 Ge 0.902 O 0.057 films. They were 7.42 × 10 −15 and 2.07 × 10 −14 V 2 /Hz at 23 Hz, respectively. The corresponding 1/f -noise coefficients, K f , of the devices were 3.65 × 10 −14 and 3.01 × 10 −14 , respectively.The voltage noise PSD was reduced as the annealing time and temperature were increased. The lowest measured noise was 1.96 × 10 −14 V 2 /Hz at the corner frequency, 12 Hz, on a device with Si 0.034 Ge 0.899 O 0.067 film annealed at 300°C for 4 h, before annealing the noise was 4.09 × 10 −13 V 2 /Hz at 12 Hz. This corresponds to a factor of 24 reduction of noise. The testing results demonstrate that annealing at higher temperature 300°C reduced the low-frequency voltage noise PSD more than that of 200°C and 250°C temperatures.

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Amorphous Ge x Si 1-x and Ge x Si 1-x O y thin films for uncooled microbolometers

Cited by 5 publications

References 21 publications

Rectifying and Schottky characteristics of a-Si_xGe_1−xO_y with metal contacts

Rectifying and Schottky characteristics of a-Si_xGe_1−xO_y with metal contacts

Recent Developments in Wearable NEMS/MEMS-Based Smart Infrared Sensors for Healthcare Applications

Noise Reduction of Amorphous Si_xGe_yO_1–x–yThin Films for Uncooled Microbolometers by Si₃N₄Passivation and Annealing in Vacuum

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Amorphous Ge x Si 1-x and Ge x Si 1-x O y thin films for uncooled microbolometers

Cited by 5 publications

References 21 publications

Rectifying and Schottky characteristics of a-SixGe1−xOy with metal contacts

Rectifying and Schottky characteristics of a-SixGe1−xOy with metal contacts

Recent Developments in Wearable NEMS/MEMS-Based Smart Infrared Sensors for Healthcare Applications

Noise Reduction of Amorphous SixGeyO1–x–yThin Films for Uncooled Microbolometers by Si3N4Passivation and Annealing in Vacuum

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Rectifying and Schottky characteristics of a-Si_xGe_1−xO_y with metal contacts

Rectifying and Schottky characteristics of a-Si_xGe_1−xO_y with metal contacts

Noise Reduction of Amorphous Si_xGe_yO_1–x–yThin Films for Uncooled Microbolometers by Si₃N₄Passivation and Annealing in Vacuum