scholarly journals Fabrication of Microbolometer Arrays Based on Polymorphous Silicon–Germanium

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2716 ◽  
Author(s):  
Ricardo Jimenez ◽  
Mario Moreno ◽  
Alfonso Torres ◽  
Alfredo Morales ◽  
Arturo Ponce ◽  
...  
Keyword(s):  
Silicon Germanium ◽  
Mechanical Stability ◽  
Electrical Characterization ◽  
Chemical Vapor ◽  
Amorphous Semiconductor ◽  
Polarization Current ◽  
Infrared Sensors ◽  
Voltage Responsivity ◽  
Germanium Alloy ◽  
Semiconductor Matrix

This work reports the development of arrays of infrared sensors (microbolometers) using a hydrogenated polymorphous silicon–germanium alloy (pm-SixGe1-x:H). Basically, polymorphous semiconductors consist of an amorphous semiconductor matrix with embedded nanocrystals of about 2–3 nm. The pm-SixGe1-x:H alloy studied has a high temperature coefficient of resistance (TCR) of 4.08%/K and conductivity of 1.5 × 10−5 S∙cm−1. Deposition of thermosensing film was made by plasma-enhanced chemical vapor deposition (PECVD) at 200 °C, while the area of the devices is 50 × 50 μm2 with a fill factor of 81%. Finally, an array of 19 × 20 microbolometers was packaged for electrical characterization. Voltage responsivity values were obtained in the range of 4 × 104 V/W and detectivity around 2 × 107 cm∙Hz1/2/W with a polarization current of 70 μA at a chopper frequency of 30 Hz. A minimum value of 2 × 10−10 W/Hz1/2 noise equivalent power was obtained at room temperature. In addition, it was found that all the tested devices responded to incident infrared radiation, proving that the structure and mechanical stability are excellent.

Low-Temperature Epitaxial Growth of Silicon and Silicon-Germanium Alloy by Ultrahigh-Vacuum Chemical Vapor Deposition

1994 ◽  
Vol 33 (Part 1, No.1A) ◽  
pp. 240-246 ◽  
Author(s):  
Tz-Guei Jung ◽  
Chun-Yen Chang ◽  
Ting-Chang Chang ◽  
Horng-Chih Lin ◽  
Tom Wang ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Low Temperature ◽  
Epitaxial Growth ◽  
Vapor Deposition ◽  
Silicon Germanium ◽  
Ultrahigh Vacuum ◽  
Chemical Vapor ◽  
Germanium Alloy

High-Efficiency Microcrystalline Silicon and Microcrystalline Silicon-Germanium Alloy Solar Cells

2011 ◽  
Vol 1321 ◽  
Author(s):  
Takuya Matsui ◽  
Michio Kondo
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Silicon Germanium ◽  
High Efficiency ◽  
Chemical Vapor ◽  
Microcrystalline Silicon ◽  
Cell Parameters ◽  
Germanium Alloy ◽  
Doping Technique ◽  
Material Studies

ABSTRACTThis paper presents our material studies on hydrogenated microcrystalline silicon (μc-Si:H) and microcrystalline silicon-germanium alloy (μc-Si1-xGex:H) thin films for the development of high efficiency p-i-n junction solar cells. In μc-Si:H solar cells, we have evaluated the structural properties of the intrinsic μc-Si:H layers grown by plasma-enhanced chemical vapor deposition at high deposition rates (>2 nm/s). Several design criteria for the device grade μc-Si:H are proposed in terms of crystallographic orientation, grain size and grain boundary passivation. Meanwhile, in μc-Si1-xGex:H solar cells, we have succeeded in boosting the infrared response of solar cell upon Ge incorporation up to x∼0.2. Nevertheless, a degradation of solar cell parameters is observed for large Ge contents (x>0.2) and thick i-layers (> 1 μm), which is attributed to the influence of the Ge dangling bonds that act as acceptorlike states in undoped μc-Si1-xGex:H. To improve the device performance, we introduce an oxygen doping technique to compensate the native defect acceptors in μc-Si1-xGex:H p-i-n solar cells.

Low Resistivity Boron Doped Amorphous Silicon-Germanium Alloy Films Obtained with a Low Frequency

2003 ◽  
Vol 796 ◽  
Author(s):  
Plasma A. Heredia-J ◽  
A. Torres-J ◽  
F.J. De la Hidalga-W ◽  
A. Jaramillo-N ◽  
J. Sanchez-M ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Silicon Germanium ◽  
Low Frequency ◽  
Chemical Vapor ◽  
Refraction Index ◽  
Alloy Films ◽  
Boron Doped ◽  
Structural And Electrical Properties ◽  
Germanium Alloy ◽  
Amorphous Silicon Germanium

AbstractThe structural and electrical properties of boron doped amorphous silicon-germanium alloy films, obtained using a low frequency plasma enhanced chemical vapor deposition (LF PECVD), are presented in this contribution. These thin films were deposited on a substrate heated at 270°C, and by decomposing a mixture of silane, germane, and diborane gases. The chemical bond structure was studied by Infrared Spectroscopy. Our results show that, for a constant diborane flow, the increase of germane flow enhances the incorporation of boron into the film; the peak at 2540 cm−1 becomes larger as the Ge content increases. Transport of carriers was studied by measuring current-voltage curves as a function of temperature. The conductivity increased from 10−6 to 10 (Ω-cm)−1, while the refraction index increased from 3.312 to 4.4458, for an increasing Ge content; this makes the films suitable for optical waveguide applications. On the other hand, the activation energy varied from 0.668 to 0.220 eV when the sample was doped with boron. The AFM images showed that the surface roughness was improved for an alloy with 50% of Ge.

Reduction of residual stress in polymorphous silicon germanium films and their evaluation in microbolometers

2020 ◽  
Vol 89 (3) ◽  
pp. 30101
Author(s):  
Ricardo Jimenez ◽  
Mario Moreno ◽  
Alfonso Torres ◽  
Roberto Ambrosio ◽  
Aurelio Heredia ◽  
...  
Keyword(s):  
Residual Stress ◽  
Silicon Germanium ◽  
Mechanical Stability ◽  
Thermal Response ◽  
High Sensitivity ◽  
Process Conditions ◽  
Voltage Responsivity ◽  
Thermal Response Time ◽  
Dc Current ◽  
Infrared Vision

Hydrogenated polymorphous silicon germanium (pm-SixGe1–x:H) thin films were deposited by the PECVD technique at 200 °C. Three compositions were investigated by changing the silane/germane gas mixture. It was found that the temperature coefficient of resistance (TCR) varies from 2.25% K−1 to 4.26% K−1 while the electrical conductivity ranges from 9.1 × 10−6 S cm−1 to 3.7 × 10−3 S cm−1. On the other hand, the residual stress of as-deposited films was highly compressive reaching values of nearly 700 MPa. After a thermal annealing of 3 hours, it was observed an acceptable reduction and a slight change towards tensile stress. A thin film with low residual stress and high TCR was chosen to manufacture test microbolometers in order to assess if the thermosensing properties of pm-SixGe1–x:H were not affected. After fabricating the microbolometers, their structural conditions were evaluated by scanning electron microscopy and it was found that the reduction of stress significantly improved their mechanical stability and reduced the warping of the membranes. Finally, test structures were characterized at a chopper frequency of 30 Hz, with a DC current of 2.5 μA in a vacuum environment of 20 mTorr. Voltage responsivity of 1.9 × 106 V/W, detectivity of 4.4 × 108 cm ∙ Hz1/2/W, NEP of 1 × 10−11 W/Hz1/2, NETD of 18 mK and 2 ms of thermal response time were measured. In summary, we have studied different process conditions to obtain better pm-SixGe1–x:H films in terms of their electrical and mechanical properties. In this sense, the results obtained with microbolometers show that pm-SixGe1–x:H is a very attractive material to develop infrared vision systems with high sensitivity.

Study of the effect of the deposition RF power on the characteristics of microcrystalline Silicon-Germanium thin films produced by PECVD

MRS Advances ◽  
2018 ◽  
Vol 3 (64) ◽  
pp. 3939-3947
Author(s):  
Arturo Torres ◽  
Mario Moreno ◽  
Pedro Rosales ◽  
Miguel Domínguez ◽  
Alfonso Torres ◽  
...  
Keyword(s):  
Thin Films ◽  
Silicon Germanium ◽  
Optical Band Gap ◽  
Electrical Characterization ◽  
Chemical Vapor ◽  
Rf Power ◽  
Microcrystalline Silicon ◽  
Film Properties ◽  
Silicon And Germanium

ABSTRACTHydrogenated microcrystalline Silicon-Germanium (μc-SiGe:H) thin films were deposited using the Plasma Enhanced Chemical Vapor Deposition (PECVD) technique from a gas mixture of SiH4, GeH4, H2 and Ar at a substrate temperature of 200 ° C. The films were deposited at a pressure of 1.5 Torr, while the RF power was varied in the range of 20 W to 35 W. Structural, optical and electrical characterization was performed in the films, Fourier Transform Infrared Spectroscopy (FTIR) was performed in order to analyze the hydrogen bonding of silicon and germanium, while Raman spectroscopy was used in order to analyze the crystallinity of the films. Through the optical and electrical characterization of the films, parameters such as the optical band gap (Eg) and the activation energy (EA) were obtained, respectively. The conductivity of the films changed up two to orders of magnitude from dark conditions to illumination AM 1.5. Finally, the correlation between deposition RF power and the film properties is presented.

Properties of Catalytic-Cvd Amorphous Silicon-Germanium (a-SiGe:H)

1990 ◽  
Vol 192 ◽  
Author(s):  
Hideki Matsumura ◽  
Masaaki Yamaguchi ◽  
Kazuo Morigaki
Keyword(s):  
Amorphous Silicon ◽  
Silicon Germanium ◽  
Hydrogenated Amorphous Silicon ◽  
Chemical Vapor ◽  
Characteristic Energy ◽  
Optical Band Gaps ◽  
Spin Resonance ◽  
Amorphous Silicon Germanium ◽  
Conductive Properties ◽  
Hydrogenated Amorphous

ABSTRACTHydrogenated amorphous silicon-germanium (a-SiGe:H) films are prepared by the catalytic chemical vapor deposition (Cat-CVD) method using a SiH4, GeH4 and H4 gas mixture. Properties of the films are investigated by the photo-thermal deflection spectroscopy (PDS) and electron spin resonance (ESR) measurements, in addition to the photo-conductive and structural studies. It is found that the characteristic energy of Urbach tail, ESR spin density and other photo-conductive properties of Cat-CVD a-SiGe:H films with optical band gaps around 1.45 eV are almost equivalent to those of the device quality glow discharge hydrogenated amorphous silicon (a-Si:H).

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