Uncooled micro-bolometer based on amorphous germanium film

The fabrication and characterization of an uncooled micro-bolometer, in which the sensing material is amorphous germanium (a-Ge:F) is presented. In order to obtain thermal isolation, the micro-bolometer was fabricated on a silicon dioxide membrane, which was made on a silicon wafer by micro-machining techniques. The sensing layer was deposited from GeF4 + H-2 mixture by low frequency plasma-enhanced chemical vapor deposition. The a-Ge:F film had high thermal coefficient of resistance at room temperature alpha = 0.04 and moderate conductivity sigma(RT) = 2.5 x 10(-3) Omega(-1) cm(-1). The micro-bolometer was characterized by the measurements of current voltage characteristics in dark and under infrared illumination with a black body at temperature T-bb = 1123 K. Thermal and noise characteristics were also measured. The micro-bolometer having the pixel area A(d) = 60 x 60 mum(2) demonstrated thermal resistance R-th= 5 x 10(6) K W-1, current responsivity R-1, = 6.2 mA W-1, voltage responsivity R-V = 4.2 x 10(6) V W-1 and detectivity D* = 8 x 10(6) cm. W Hz(1/2). (C) 2003 Elsevier B.V. All rights reserved.