<title>Comparison of infrared detection mechanisms in thermal-emissive vs. photoemissive silicon Schottky barrier arrays</title>

Abstract

Infrared imaging based on photoemission in metal-suicide/silicon Schottky barrier arrays is a mature technology that is currently employed in both military and commercial applications. Metal-suicide/silicon Schottky diodes can also be employed in uncooled bolometer arrays. The bolometer detection mechanism is thermionic emission in the Schottky barrier. Schottky bolometer array technology is expected to have both performance and production advantages, when compared with current uncooled sensor technology. In this paper, we compare the physical mechanisms involved in the two Schottky barrier based infrared sensors. We will also present a simplified model for the noise equivalent temperature of each technology.

A low cost multi quantum SiGe/Si/Schottky structure for high performance IR detectors

“…An expression for the temperature coefficient of resistance (current) in a Schottky diode is given by [5]: [2] The φ bn for SQW1 and SQW2 are estimated to 0.26 and 0.42 eV. This difference introduces a remarkable improvement in the temperature response of SQW2 compared to SQW1.…”

“…The magnitude of the saturation current will be proportional to the electrically active area of the Schottky junction. In this case, thermionic emission is the dominant mechanism in producing the saturation current [5]. The saturation current density can be written as: [1] where A r is Richardson's constant, k is Boltzmann's constant, T the absolute temperature.…”

“…This study proposes that a Schottky diode in series with the multi-quantum layer stack can increase the sensitivity of the thermistor material. The advantage of a Schottky diode is the log-linear temperature dependence of Richardson thermionic emission currents in reverse-biased condition [4][5][6]. Such designs demonstrates very high TCR values in range of 6-7%/K [5] and independency to Flicker noise makes them good candidates for IR detection.…”

“…The advantage of a Schottky diode is the log-linear temperature dependence of Richardson thermionic emission currents in reverse-biased condition [4][5][6]. Such designs demonstrates very high TCR values in range of 6-7%/K [5] and independency to Flicker noise makes them good candidates for IR detection. High resistance due to the potential barrier at the interface of the metal and semiconductor (Si) results in low current in these detectors.…”

“…1/f noise as mentioned earlier is proportional to the current and in this case with low operating current, Johnson noise is the dominant noise source. Thus, by optimizing the resistance through improving the contacts, the resistance and in turn Johnson noise will be reduced [5].…”