A novel contemporary approach of integrating micro-electronics into flexible wearable e-textile for muscle physiology detection is presented here. Textile sensor array is used for camera-less, real-time, and continuous monitoring of muscle activations and movements. The functionality is amplified with an aid of near infrared spectroscopy (NIRS) sensors to monitor the metabolism during the movement. This multi-modal sensing wearable e-textile has a huge potential to integrate and commercialize futuristic health monitoring wearables.
This article reports techniques used for reduction of the dark current density of amorphous silicon (a-Si:H) p-i-n photodetectors under reverse bias to the 10-12 A/cm2 range. This range of dark currents is critical in applications involving low-level light detection. The dark current of these devices is significantly affected by the quality of the p-i interface and the band-gap of the p-type material. The latter can be addressed by employing of a p-type large band-gap (2.23eV) material such as amorphous silicon carbide (a-SiC:H) layer so as to increase the built-in potential at the junction. This should decrease the dark current, however, the transition from a-Si:H to the large band gap p-type a-SiC:H layer leads to a band-gap discontinuity, which can degrade the integrity of the interface. Thus, a graded layer is introduced at the p-i interface to provide a smooth transition of energies over a few monolayers. In addition, a thin insulating silicon carbide p-layer is introduced prior to deposition of the heavily doped p-region to further reduce the dark current.
KEYWORDS: Thin films, Transistors, Annealing, Silicon, Analog electronics, Organic light emitting diodes, Data modeling, Amorphous silicon, Switching, Chemical species
In this work, we have investigated and modeled an anomalous transient behaviour of the hydrogenated amorphous silicon (a-Si:H) thin film transistor (TFT) in a time scale (of the order of hundreds of seconds) where the threshold voltage shift is not prominent. Such a long term transient in the terminal characteristics can be critical in analog applications of the TFT, such as in pixel driver circuits of organic light emitting diode (OLED) displays. The reproducibility of the transient behaviour regardless of the presence or absence of any thermal annealing cycle suggests that the behaviour is not related to the metastable creation of defects in a-Si:H. The underlying mechanism that we believe is a configurational relaxation of Si dangling bond (D) defects after change in their charge states. Other possible effects including the properties of the source and drain contacts are carefully considered. Based on the defect relaxation mechanism, we have proposed a time dependent drain current model to describe the transient response of the TFT in the forward above threshold regime of operation. The parameters associated with the model are physically based and have strong dependence on the TFT geometry. The measurement data are in good agreement with the simulation results with a discrepancy of less than 5%, thus validating the model.
This paper reviews design considerations pertinent to amorphous silicon (a-Si:H) thin film transistor (TFT) based drive circuits for active matrix organic light emitting diode (AMOLED) displays. Critical design and performance issues related to the a-Si:H TFT are described along with the optimisation of pixel circuit parameters for high lifetime, low power, high resolution, and high frame rate AMOLED displays.
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.