noise reduction of si x ge 1-x and si x ge 1-x o y bolometers by forming gas passivation
DESCRIPTION
Noise Reduction Of Si x Ge 1-x and Si x Ge 1-x O y Bolometers by Forming Gas Passivation. Mukti Rana and Donald Butler University of Texas at Arlington Electrical Engineering Dept. Arlington, TX 76019 Based in part by work supported by the National Science Foundation ECS-0322900. - PowerPoint PPT PresentationTRANSCRIPT
Noise Reduction Of SixGe1-x and SixGe1-xOy Bolometers by Forming Gas Passivation
Mukti Rana and Donald Butler
University of Texas at Arlington
Electrical Engineering Dept.
Arlington, TX 76019
Based in part by work supported by the National Science Foundation
ECS-0322900
Bolometer
• Bolometers are the optical sensors whose resistivity varies with temperature. When lights fall on the bolometer surface the sensing material of the bolometer absorbs heat and there by changes it’s resistance.
Why Noise Reduction is important
• Noise detoriates the Bolometer’s performance by reducing the detectivity, responsivity.
• Amorphous films are characterized by higher noise.
Bolometer Fabrication
p-Si Substrate
Ni PadAl Mirror
SiN Insulation Layer
PI 2737 Sacrificial Layer
Ni ContactSiN NiCr ArmSiGeO
NiCr AbsorberSiN
Ashing of PI2737 in Oxygen Plasma
Micormacined Bolometer : SEM Picture
Experimental Details of Forming Gas Passivation
• The Bolometer’s noise was measured in a shielded probe station with the help of SRC560 low noise preamplifier, HP 3562 dynamic signal analyzer and a computer. The noise spectra of same device was measured before and after the passivation to compare the noise.
• An AXIC Jet First Rapid Thermal Anneal (RTA) was used for annealing the sample. The sample was kept inside the chamber at a forming gas flow of 500 SCCM for different intervals of time.
Results: Noise Voltage Power Spectral Density (PSD) at 0.6uA Bias Current of SiGeO Bolometer Before and After Forming Gas Passivation
10-16
10-15
10-14
10-13
10-12
10-11
10-10
10-9
1 10 100 1000 104
Before PassivationAfter 2 Hours PassivationAfter 3 Hours PassivationAfter 4Hours PassivationAfter 8 Hours Passivation
Noi
se V
olta
ge P
SD [V
2 /Hz]
Frequency [Hz]