Responsivity

About: Responsivity is a research topic. Over the lifetime, 9918 publications have been published within this topic receiving 186118 citations.

An integrated superconductive magnetic nanosensor for high-sensitivity nanoscale applications.

Abstract: An integrated magnetic nanosensor based on a niobium dc SQUID (superconducting quantum interference device) for nanoscale applications is presented. The sensor, having a washer shape with a hole of 200 nm and two Josephson–Dayem nanobridges of 80 nm × 100 nm, consists of a Nb(30 nm)/Al(30 nm) bilayer patterned by electron beam lithography (EBL) and shaped by lift-off and reactive ion etch (RIE) processes. The presence of the niobium coils, integrated on-chip and tightly coupled to the SQUID, allows us to easily excite the sensor in order to get the voltage–flux characteristics and to flux bias the SQUID at its optimal point. The measurements were performed at liquid helium temperature. A voltage swing of 75 µV and a maximum voltage–flux transfer coefficient (responsivity) as high as 1 mV/Φ0 were directly measured from the voltage–flux characteristic. The noise measurements were performed in open loop mode, biasing the SQUID with a dc magnetic flux at its maximum responsivity point and using direct-coupled low-noise readout electronics. A white magnetic flux noise spectral density as low as 2.5 μΦ0 Hz−1/2 was achieved, corresponding to a magnetization or spin sensitivity in units of the Bohr magneton of 100 spin Hz−1/2. Possible applications of this nanosensor can be envisaged in magnetic detection of nanoparticles and small clusters of atoms and molecules, in the measurement of nanoobject magnetization, and in quantum computing.

A 1024-element bulk-micromachined thermopile infrared imaging array

Abstract: This paper reports on a bulk-micromachined silicon uncooled thermal imager intended for use in automated semiconductor process control. The device has a responsivity of 15 V/W, a thermal time constant of 1 ms, and a D* of 1.6×107 cm Hz1/2/W. It is organized as a 32×32-element area array with on-chip address generation, multiplexing, and self-test circuitry. The overall chip size is 16 mm×16 mm, with a 12 mm×12 mm imaging area. Each detector consists of 32 n–p polysilicon thermocouples supported on a dielectric window and is micromachined using a novel combined front-undercut and back-etched process. An infrared camera system using the imager is also described.

Effect of asymmetric Schottky barrier on GaN-based metal-semiconductor-metal ultraviolet detector

Abstract: An asymmetric Schottky barrier metal-semiconductor-metal (MSM) ultraviolet (UV) detector with Ni/GaN/Au structure was designed and the effect of the asymmetric Schottky barrier on the detector response was investigated. This detector had response at 0 V bias and increased responsivity when a positive bias was applied to the Ni/GaN contact; however, the internal gain disappeared when a negative bias was applied to this point. This contrasts with a symmetric Ni/GaN/Ni Schottky barrier MSM UV detector which had no internal gain under positive/negative bias and almost no response at 0 V bias. The improved performance of the asymmetric Schottky barrier detector was because of the lower work function of Au causing reduction of Schottky barrier and hence enhancing a hole-accumulating and trapping process, which resulted in internal gain.

Quantum dot infrared photodetectors

Abstract: We discuss key issues related to quantum dot infrared photodetectors. These are the normal incidence response, the dark current, and the responsivity and detectivity. It is argued that the present devices have not fully demonstrated the potential advantages. The dominant infrared response in devices so far is polarized in the growth direction. The observed dark currents are several orders of magnitude higher than those for quantum well photodetectors; while ideally they should be lower. The areas that need improvements are pointed out.