Ultra-sensitive radiation dosimeters

Abstract

An apparatus comprises a conducting substrate layer, a dielectric layer formed over the conducting substrate layer, a channel formed over at least a portion of the dielectric layer and first and second source/drain regions formed on respective first and second portions of the channel. The channel comprises a thin-film carbon material. The conducting substrate layer, the dielectric layer, the channel and the first and second source/drain regions are configured such that exposure to radiation causes a change in a threshold voltage of the apparatus.

What is claimed is: 
     
         1 . An apparatus, comprising:
 a conducting substrate layer;   a dielectric layer formed over the conducting substrate layer;   a channel formed over at least a portion of the dielectric layer; and   first and second source/drain regions formed on respective first and second portions of the channel;   wherein the channel comprises a thin-film carbon material; and   wherein the conducting substrate layer, the dielectric layer, the channel and the first and second source/drain regions are configured such that exposure to radiation causes a change in a threshold voltage of the apparatus.   
     
     
         2 . The apparatus of  claim 1 , wherein the thin-film carbon material is graphene. 
     
     
         3 . The apparatus of  claim 1 , wherein the thin-film carbon material is a carbon nanotube array. 
     
     
         4 . The apparatus of  claim 1 , wherein the conducting substrate layer is one of a heavily-doped silicon substrate material, a flexible polymer material, a thin-film transistor substrate and a silicon carbide substrate material. 
     
     
         5 . The apparatus of  claim 1 , wherein the dielectric layer is one of a silicon dioxide insulator and a silicon nitride insulator. 
     
     
         6 . The apparatus of  claim 1 , wherein the dielectric material can be annealed to release trapped charges. 
     
     
         7 . The apparatus of  claim 1 , wherein the channel material provides high dosimetric sensitivity compared to a fully-depleted silicon-on insulator (FDSOI) metal oxide semiconductor field effect transistor (MOSFET). 
     
     
         8 . The apparatus of  claim 1 , wherein a thickness of the dielectric layer is determined as a function of a desired dosimetric sensitivity. 
     
     
         9 . The apparatus of  claim 1 , wherein the thickness of the dielectric layer is about 300 nm. 
     
     
         10 . The apparatus of  claim 1 , wherein the threshold voltage of the apparatus increases linearly as the exposure to radiation increases. 
     
     
         11 . A radiation dosimeter, comprising:
 at least one transistor comprising a conducting substrate, a dielectric layer formed on the conducting substrate, a thin-film carbon channel formed on the dielectric layer, and first and second source/drain regions formed on respective first and second portions of the thin-film carbon channel;   a display coupled to the at least one transistor; and   processing circuitry;   wherein the at least one transistor is configured such that exposure to radiation causes a change in a threshold voltage of the at least one transistor, a radiation level is a function of a difference between the threshold voltage of the transistor after exposure to radiation and a threshold voltage of the transistor before exposure to radiation, and the processing circuitry is operative to calculate the radiation level and output the radiation level on the display.   
     
     
         12 . The radiation dosimeter of  claim 11 , wherein the thin-film carbon channel is a graphene layer. 
     
     
         13 . The radiation dosimeter of  claim 11 , wherein the thin-film carbon channel is a carbon nanotube array. 
     
     
         14 . The radiation dosimeter of  claim 11 , further comprising an annealing component operative to expose at least the dielectric layer of the transistor to a given temperature. 
     
     
         15 . The radiation dosimeter of  claim 11 , wherein the conducting substrate layer is one of a heavily-doped silicon substrate material, a flexible polymer material, a thin-film transistor substrate and a silicon carbide substrate material. 
     
     
         16 . The radiation dosimeter of  claim 11 , wherein the dielectric layer is one of a silicon dioxide insulator and a silicon nitride insulator. 
     
     
         17 . The radiation dosimeter of  claim 11 , further comprising an alarm component operative to output an alarm if the radiation level is above a specified threshold level. 
     
     
         18 . The radiation dosimeter of  claim 11 , wherein the threshold voltage of the transistor increases linearly as the exposure to radiation increases. 
     
     
         19 . A radiation detection system, comprising:
 at least one transistor comprising a conducting substrate, a dielectric layer formed on the conducting substrate, a thin-film carbon channel formed on the dielectric layer, and first and second source/drain regions formed on respective first and second portions of the thin-film carbon channel, the at least one transistor being configured such that exposure to radiation causes a change in a threshold voltage of the at least one transistor;   a memory; and   a processor device operatively coupled to the memory and configured to:   calculate a radiation level, the radiation level being a function of a difference between the threshold voltage of the transistor after exposure to radiation and a threshold voltage of the transistor before exposure to radiation; and   output the radiation level to a display.   
     
     
         20 . The system of  claim 19 , wherein the thin-film carbon channel is a graphene layer. 
     
     
         21 . The system of  claim 19 , wherein the thin-film carbon channel is a carbon nanotube array. 
     
     
         22 . The system of  claim 19 , wherein the threshold voltage of the at least one transistor increases linearly as the exposure to radiation increases.