We have investigated the feasibility of significantly improving the performance of currently favored uncooled
infrared (IR) detectors based on Si or VOx microbolometers with a new design employing freestanding suspended
network of single-walled carbon nanotubes (SWCNTs). Such networks have high absorption coefficient, high
temperature coefficient of the resistance (TCR) and extremely low thermal mass. This combination of parameters
translates into an uncooled IR detector with high sensitivity and a very fast temporal response. We show estimates
of key parameters for such a device, demonstrate a method to prepare it using suspended SWCNT networks
achieved by selective removal of a sacrificial oxide layer, thereby forming a cavity under the SWCNT network. We
also present TCR and photothermal bolometric response data of this conceptual structure.
The advantages and applications of chalcogenide glass (ChG) thin film photoresists for grayscale lithography are demonstrated. It is shown that the ChG films can be used to make ultrathin (~600 nm), high-resolution grayscale patterns, which can find their application, for example, in IR optics. Unlike polymer photoresists, the IR transparent ChG patterns can be useful as such on the surface or can be used to transfer the etched pattern into silicon or other substrates. Even if the ChG is used as an etch mask for the silicon substrate, its greater hardness can achieve a greater etch selectivity than that obtained with organic photoresists. The suitability of ChG photoresists is demonstrated with inexpensive and reliable fabrication of ultrathin Fresnel lenses that are transparent in the visible as well as in the IR region. The optical functionality of the Fresnel lenses is confirmed. Application of silver photodissolution in grayscale lithography for microelectromechanical systems (MEMS) applications is also shown. A substrate to ChG/silver thickness etching ratio of ~10 is obtained for the transfer of patterns into silicon using reactive ion etching (RIE), more than a fivefold increase compared to traditional polymer photoresist.
The advantages and applications of chalcogenide glass (ChG) thin film photoresists for grayscale lithography are
demonstrated. It is shown that the ChG films can be used to make ultrathin (~600 nm), high-resolution grayscale
patterns, which can find their application, for example, in IR optics. Unlike polymer photoresists, the IR transparent
ChG patterns can be useful as such on the surface, or be used to transfer the etched pattern into silicon or other
substrates. Even if the ChG is used as an etch mask for the silicon substrate, its greater hardness can achieve a greater
transfer ratio than that obtained with organic photoresists. The suitability of ChG photoresists is demonstrated with
inexpensive and reliable fabrication of ultrathin Fresnel lenses that are transparent in the visible as well as in the IR
region. The optical functionality of the Fresnel lenses is confirmed. Application of silver photodissolution in grayscale
lithography for MEMS applications is also shown. The process consists of the following steps: ChG film deposition, Ag
film deposition, irradiation through a grayscale mask, removal of the excess Ag and the transfer of the pattern to Si by
dry etching. A substrate to ChG thickness etching ratio of ~ 10 is obtained for the transfer of patterns into silicon, more
than a five fold increase compared to traditional polymer photoresist.
The influence of γ-irradiation on optical properties of the pseudobinary "stoichiometric" Sb2S3-GeS2 and the non-stoichiometric Sb2S3-Ge2S3 chalcogenide glasses (ChG) prepared by a standard melt-quenching method is studied. It is established that in the case of the both investigated cut-sections the "γ-darkening" effect (i.e. the "red" shift of the fundamental optical absorption edge), consisting the dynamic (relaxing with time) and the static (remaining constant approximately two months after irradiation) components, takes place. The comparison of compositional trend of the "γ-darkening" effect for the pseudobinary and the non-stoichiometric investigated ChG is made. Phenomenological description of the observed effects is carried out taking the degree of chemical bond metallization, concentration of chemical bonds and free volume parameters into consideration.
The influence of gamma-irradiation on the optical properties of GexSb40-xS60 chalcogenide glassy system is studied. It is established that long-wave shift of the optical absorption edge or 'gamma-darkening' effect in the investigated glasses depends on their chemical composition or average coordination number Z. The maximum gamma-irradiation effect is observed near the point of Z approximately equals 2.67 and it is absent in Sb-rich ternary bulk samples. The gamma-induced changes of the optical absorption are unstable and restores to some residual value after the period of approximately 2 months. The observed features of the gamma-induced effect are discussed in terms of the compositional dependencies of compactness and fraction of chemical bonds, determined according to the ordered bond network model.
The effect of gamma-irradiation on the IR optical properties of the ternary chalcogenide glasses (ChG) of Ge-Sb-S system is investigated. The IR optical transmission spectra in the 4000 - 1000 cm-1 (2.5 - 10 micrometer) region of stoichiometric line (STL) Sb2S3-GeS2 and non- stoichiometric line (NSTL) Sb2S3-Ge2S3 glass compositions are measured. The compositional dependences of intensity of the main impurity absorption bands connected with the existence of oxygen-, hydrogen- and carbon-containing groups in the glass matrix before and after gamma-irradiation are analyzed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.