Study on NEP for optimization of THz Antenna-Coupled Ti Microbolometers withStraight and Meander Shaped Thermistors

摘要

Room-temperature antenna-coupled Ti microbolometers with straight wire shaped thermistors (lengths - 25, 50,10 μm and width-0.2 μm) and meander shaped thermistors (length-48.7 and width-0.2 μm) were fabricated and analyzed. Straight and meander shaped thermistor structures are shown in Fig.l (a) and (b), respectively. Sensitivity is one of the important parameter for optimizing the microbolometer characteristics, which can be analyzed in terms of noise equivalent power (NEP). To estimate the NEP, voltage noise was measured for the microbolometers with the use of dynamic signal analyzer over a frequency range of 10 Hz -10 kHz. To enhance the bolometer performance maximum allowable bias current was applied at the thermistors. The measured spectra shown in Fig.2 (a) exhibits both frequency and bias current dependence. The bias current dependence can be clearly seen as the noise voltage gradually increases with the increased bias current. Fig.2 (b) represents the dependence of voltage noise and bias current on lengths of the thermistor. Since the noise voltage is direct proportional of resistance, the longest bolometer shows larger noise voltage than the others, though its applied bias current is small. Trade-off between NEP and responsivity (Rv) has been shown in Fig.2 ©.