Ionizing Radiation Total Dose Detectors Using Oligomer Organic Semiconductor Material and Devices
- PDF / 253,761 Bytes
- 6 Pages / 432 x 648 pts Page_size
- 81 Downloads / 188 Views
Ionizing Radiation Total Dose Detectors Using Oligomer Organic Semiconductor Material and Devices Harshil N. Raval and V. Ramgopal Rao Centre of Excellence in Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology, Bombay, Mumbai – 400 076, India ABSTRACT Organic semiconducting oligomer – Pentacene, as a material and organic electronic devices based on it, are proposed here as total dose detectors for ionizing radiation. Pentacene, when exposed to ionizing radiation of – rays using Cobalt – 60 (60Co) radiation source, shows increase in the conductivity of the material which can be used as a sensing phenomenon for determining the dose of ionizing radiation. The change in material property was also verified using UV-visible (UV-VIS) spectrum for pentacene thin-films with rising absorption peaks at the oxidized positions in the wavelength. A pentacene resistor can be used as a detector, as the change in the conductivity of the pentacene film can be easily quantified by measuring the change in resistance of the pentacene resistor after different total radiation dose exposures. The experiments resulted in a sensitivity of 340 k /Gy for a total 100 Gy radiation dose for the pentacene resistor. Furthermore, employing this simple electrical measurement technique for determining the dose of ionizing radiation and to improve the sensitivity of the sensor by transistor action, a pentacene based organic field effect transistor (OFET) was exposed to ionizing radiation. Change in OFF current (IOFF) of the OFET sensor with W/L = 19350 μm/100 μm, suggests a sensitivity of 21 nA/Gy for 100 Gy dose. Also, changes in various other parameters like threshold voltage, subthreshold swing, field effect mobility, number of interface states etc. can be extracted from the electrical characterizations which prove their usefulness as a detector for ionizing radiation. INTRODUCTION Organic semiconducting polymer materials are being explored for various organic electronic applications [1-3] because of various advantages, such as, large area coverage on flexible substrates and cost effective fabrication process. These polymer semiconducting materials have also found their applications in different sensing applications due to their chemical affinity to different atmospheric conditions [4-11]. However, with the highest carrier mobility and stability, organic semiconducting oligomer – Pentacene is the most engineered and known to be the best material of choice for numerous organic electronic applications such as displays, RFID tags, and flexible circuits [12-13]. Moreover, pentacene was also explored for various sensing applications, such as, gas and vapor sensing [14], humidity sensing [15], and pH monitoring [16]. Here, we report the use of the Pentacene for determining total dose of ionizing radiation using the change in conductivity of the material as a measure of ionizing radiation dose. Pentacene resistor and a pentacene OFET are proposed here as the devices for determining ionizing radiation. EXPERIMENTS Pentacen
Data Loading...
