Abstracts Book - IMRC 2018

• SA4-P005
POLYMORPHOUS SILICON-GERMANIUM MICROBOLOMETERS FOR
INFRARED APPLICATIONS: INFLUENCE OF PIXEL GEOMETRY
Ricardo Jimenez 1 , Mario Moreno 1 , Alfonso Torres 1 , Pedro Rosales 1 , Javier de la Hidalga 1 ,
Roberto Ambrosio 2 , Adrian Itzmoyotl Toxqui 1 , Oscar Aponte 1
1
Instituto Nacional de Astrofísica, Óptica y Electrónica, Electronics, Mexico. 2 Benemerita
Universidad Autonoma de Puebla, Electronics, Mexico.
The detection of infrared radiation has multiple applications such as early
diagnosis of diseases, monitoring of industrial processes, security and military
to name a few. Uncooled microbolometers have become the preferred choice
as a radiation detector for portable and low-cost applications. These devices
consist of a membrane composed of a material with a high temperature
coefficient of resistance (TCR), which is thermally isolated by two support arms.
Traditionally, vanadium oxide and amorphous silicon have been used due to
their considerable TCR value. However vanadium oxide lacks silicon
complementary metal-oxide-semiconductor (CMOS) compatibility, thus
increasing the manufacturing cost. On the other hand amorphous silicon
possesses a high resistivity that causes a detriment in the level of noise of the
detectors and it is susceptible to the degradation induced by radiation.
Polymorphous semiconductors are mainly composed of a matrix of amorphous
material with small nanocrystals in the range of 2-5 nm that help to reduce the
density of defects and increase the stability of the films. In this work, the
fabrication of microbolometers based on polymorphous silicon-germanium
(pm-SixGe1-x:H) thin films is presented. Thermo-sensing films are deposited by
the technique of plasma enhanced chemical vapor deposition (PECVD) at 200 °C
and its electrical properties are set by adjusting the deposition parameters.
Devices with two support arm lengths were tested, and their effect on thermal
insulation was evaluated by means of their response to infrared radiation.
Responsivity and noise were measured in order to calculate detectivity. The
results obtained have demonstrated its feasibility to develop an infrared vision
system with high sensitivity.
Keywords: microbolometers, polymorphous, infrared
Presenting authors email: rjzavala@inaoep.mx