Radio Frequency sputtered Si1−xGex and Si1−xGexOy thin films for uncooled infrared detectors

Rana, Mukti M.; Butler, Donald P.

doi:10.1016/j.tsf.2006.02.088

Cited by 24 publications

(8 citation statements)

References 20 publications

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“…Figure 3 shows the noise voltage PSD for slbl at 0.3 |iA bias current at different passivation times. Noise sources in the bolometer are mainly due to the sensing layer of Sii-xGCxOy [2]. The value of Kf depends on the quality of the crystal, and on the scattering mechanisms that determine the mobility // [6].…”

Section: Resultsmentioning

confidence: 99%

“…The fabrication of microbolometer pixels, the forming gas passivation, and current voltage (I-V) measurement techniques are presented elsewhere [2]. Figure 1 (a) and 1 (b) show the cross sectional schematic view and a SEM micrograph of the fabricated amorphous Sii-xGcxOy microbolometers respectively.…”

Section: Methodsmentioning

confidence: 99%

“…Six possible noise sources affecting bolometers are Johnson noise, shot noise, generation recombination (g-r) noise, flicker noise (1//), temperature fluctuation noise, and background radiation noise and limit the microbolometer's performance [1]. The dependency of microbolometer's figures of merits on noise sources are discussed elsewhere [2]. Among these noise sources, l//-noise plays a significant role in determining the microbolometer's performance [3].…”

Section: Introductionmentioning

confidence: 99%

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Noise Sources of a-Si[sub 1−x]Ge[sub x]O[sub y] Microbolometers And Their Reduction By Forming Gas Passivation

Rana¹,

Butler²,

Macucci³

et al. 2009

AIP Conference Proceedings

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Forming gas annealing was performed on Sii.xGe^Oy microbolometers in order to reduce the electrical 1//^noise. The passivation time and temperature were optimized to obtain least possible noise voltage power spectral density (PSD). To observe the effect of forming gas annealing at different intervals of time on the noise voltage PSD of the devices, the noise voltage PSD was measured before and at the end of each interval of passivation time by tracking individual devices. The microbolometers fabricated from Sii.xGe^Oy were placed inside a rapid thermal annealing chamber in the presence of forming gas at 250 °C with different intervals of time starting from 0.5 hour to 8 hours. The value of flicker noise coefficient . STj, or an/N from the Hooge model was used as a measure of electrical l//^noise. The l//^noise is believed to originate from the defects and dangling bonds in the sensing layer. The hydrogen passivation reduces the electrical l//^noise by repairing the dangling bonds and defects. Passivation done for excess time increased the electrical l//^noise of the device slightly, indicating that the dangling bonds contribute to trap states and scattering centers for the carriers.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Noise Sources of a-Si[sub 1−x]Ge[sub x]O[sub y] Microbolometers And Their Reduction By Forming Gas Passivation

Rana¹,

Butler²,

Macucci³

et al. 2009

AIP Conference Proceedings

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“…15 as this composition gave us the optimum TCR, device resistance, and performance (i.e., detectivity, responsivity, noise equivalent power) [11]. Also, higher Ge content of a-Si x Ge 1−x and a-Si x Ge 1−x O y sensing layers were used here as it was found in an earlier study that they exhibit higher TCR than the lower content ones [12].…”

Section: Introductionmentioning

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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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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“…VO (nonstochiometric film) in the semiconducting phase is selected as an IR-sensitive material because of its high-temperature coefficient of resistance, low noise, and low resistance, which is compatible with readout electronics. Several other materials can be used for IR detection, including amorphous silicon (a: Si) [28], yttrium barium copper oxide (YBaCuO) [29], silicon germanium (SiGe) [30], silicon germanium oxide (SiGeO) [31], [32], and metals [33]. In this paper, a dual-band microbolometer model is presented.…”

Section: Introductionmentioning

confidence: 99%

Design of Dual-Band Uncooled Infrared Microbolometer

et al. 2011

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This paper describes the design and modeling of a smart uncooled infrared detector with wavelength selectivity in the long-wavelength infrared (LWIR) band. The objective is to enhance the probability of detecting and identifying objects in a scene. This design takes advantage of the smart properties of vanadium dioxide (VO 2 ): it can switch reversibly from an IR-transparent to an IR-opaque thin film when properly triggered. This optical behavior is exploited here as a smart mirror that can modify the depth of the resonant cavity between the suspended thermistor material and a patterned mirror on the substrate, thereby altering wavelength sensitivity. The thermistor material used in the simulation is vanadium oxide (VO X ). The simulation results show that, when VO 2 is used in the metallic phase, it reflects IR radiation back to the suspended VO X and enhances IR absorption in the 9.4-10.8-m band. When the film is switched to the semiconductor phase, it admits most IR radiation, which is then reflected back to the suspended VO X by a patterned gold thin film under an SiO 2 spacer layer. The spacer layer is used to increase the resonant cavity depth underneath the microbolometer pixel. Thus, the peak absorption value is shifted to 8-9.4 m, creating the second spectral band. The detector is designed with a relatively low thermal conductance of 1.71 10 7 W/K to maximize responsivity (R v ) to values as high as 1.27 10 5 W/K and detectivity (D ) to as high as 1 62 10 9 cm Hz 1 2 /W, both at 60 Hz. The corresponding thermal time constant is equal to 2.45 ms. Hence, these detectors could be used for 60-Hz frame rate applications. The extrapolated noise equivalent temperature difference is 14 and 16 mK for the 8-9.4-and 9.4-10.8-m bands, respectively. The calculated absorption coefficients in the two spectral bands were 59% and 65%, respectively.Index Terms-Dual-band infrared (IR) detector, microbolometer, vanadium oxide (VOx).

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Radio Frequency sputtered Si1−xGex and Si1−xGexOy thin films for uncooled infrared detectors

Cited by 24 publications

References 20 publications

Noise Sources of a-Si[sub 1−x]Ge[sub x]O[sub y] Microbolometers And Their Reduction By Forming Gas Passivation

Noise Sources of a-Si[sub 1−x]Ge[sub x]O[sub y] Microbolometers And Their Reduction By Forming Gas Passivation

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

Design of Dual-Band Uncooled Infrared Microbolometer

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Radio Frequency sputtered Si1−xGex and Si1−xGexOy thin films for uncooled infrared detectors

Cited by 24 publications

References 20 publications

Noise Sources of a-Si[sub 1−x]Ge[sub x]O[sub y] Microbolometers And Their Reduction By Forming Gas Passivation

Noise Sources of a-Si[sub 1−x]Ge[sub x]O[sub y] Microbolometers And Their Reduction By Forming Gas Passivation

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

Design of Dual-Band Uncooled Infrared Microbolometer

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