11:15 AM - 11:30 AM
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[7a-A409-7] Comparative Study on Temperature Sensors for Antenna-Coupled Bolometers:
MOSFET, PN Junction Diode and Resistor
Keywords:Temperature sensor, Antenna coupled bolometer
Temperature sensor is the most important element in bolometers, and many kinds of sensors, such as resistor (thermistor), pn-junction diode, FET, etc., have been reported. However, there is a tradeoff between responsivity and output noise, and fair comparison has not been made among different devices and materials. This time, we systematically compare the performances of MOSFETs (n- and p-channel), pn-junction diodes (with and without body doping) and resistors with different materials (n+ and p+ single-crystal Si, and n+ polycrystalline Si) by assuming the 1-THz antenna-coupled bolometer that allows the area of 15 mm ´ 15 mm for the integrated heater and the temperature sensor.
To realize the antenna coupled bolometer structure the thermistor and the heater together with the insulation layer stacked between them is placed in the center of the antenna. The constant current load of 10µA is considered for the estimation of responsivity and NEP. For simplicity, the antenna coupled structure is shown only for MOSFET and Resistor as long as the same structure is assumed for diode. I-V and Noise measurement has been taken for FET (L=1µ W=5µ), Diode (L=2µ W=50µ) and Resistor (L=100µ W=1µ) devices, then the data is converged for assumed device dimension. Analytical modeling is used to estimate the responsivity of MOSFET and Diode devices. Simulation in LTspice has been performed based on the analytical model for estimating the responsivity of resistive bolometer. n- channel MOSFET device shows the maximum responsivity of 337.922V/W. NEP (Noise Equivalent Power) which is inversely proportional to the responsivity is estimated from the noise voltage at 10Hz. The comparison table clearly shows that the device with good responsivity has better NEP than others. Hence, the n- channel MOSFET can be efficiently used for THz application.
To realize the antenna coupled bolometer structure the thermistor and the heater together with the insulation layer stacked between them is placed in the center of the antenna. The constant current load of 10µA is considered for the estimation of responsivity and NEP. For simplicity, the antenna coupled structure is shown only for MOSFET and Resistor as long as the same structure is assumed for diode. I-V and Noise measurement has been taken for FET (L=1µ W=5µ), Diode (L=2µ W=50µ) and Resistor (L=100µ W=1µ) devices, then the data is converged for assumed device dimension. Analytical modeling is used to estimate the responsivity of MOSFET and Diode devices. Simulation in LTspice has been performed based on the analytical model for estimating the responsivity of resistive bolometer. n- channel MOSFET device shows the maximum responsivity of 337.922V/W. NEP (Noise Equivalent Power) which is inversely proportional to the responsivity is estimated from the noise voltage at 10Hz. The comparison table clearly shows that the device with good responsivity has better NEP than others. Hence, the n- channel MOSFET can be efficiently used for THz application.