Traditionally, focal plane arrays require extensive external focal plane electronics (FPE) to provide clocks and biases as well as to digitize the analog output signals. The FPE has to be well-designed and is typically large, heavy and powerhungry. Most importantly, the FPE has to be placed some distance away from the FPA, which complicates maintaining low noise performance throughout the complete system. To offer an alternative to the discrete electronics, Rockwell Scientific has developed a new approach known as the SIDECAR application-specific integrated circuit (ASIC). This single chip provides all the functionality necessary to operate an infrared array with the convenience of a pure digital interface to the outside world. This paper will present performance data on the latest generation of the SIDECAR ASIC operating the JWST H2RG detector arrays at cryogenic temperature. The test results demonstrate that an ASIC based FPA system will meet or exceed all performance requirements for the JWST mission. The SIDECAR ASIC has been selected by NASA to become the FPA drive electronics for all shortwave infrared instruments on JWST.
In this paper, an experimental and theoretical study is carried out of crosstalk between nearest-neighbor devices within a backside-illuminated linear HgCdTe photovoltaic infrared sensing array. The dominant form of crosstalk that occurs in high performance photovoltaic arrays is associated with photogenerated minority carriers that diffuse laterally between adjacent devices within the array. To measure crosstalk, a scanning laser microscope is used to obtain a spatial map of spot-scan photoresponse at a temperature of 80K for individual p-on-n photovoltaic devices within the linear array. These experimental results are compared to calculations performed on a commercial two-dimensional device simulation package. The crosstalk measurements and calculations presented in this paper include results on mid-wavelength infrared planar device structures, as well as long-wavelength infrared mesa-isolated devices, which give measured crosstalk values of 6.2 and 8.3%, respectively. The results indicate that the device simulations are in good agreement with experimental results. Further simulations are carried out to determine the sensitivity of crosstalk to various material and device parameters such as epitaxial layer thickness (7 to 25 µm), illumination wavelength (1.047 to 11.0 µm), minority carrier diffusion length (8 to 90 µm), and diode pitch. It is found that the dominant feature influencing the value of crosstalk is the distance between the region of photogeneration and the collecting p-n junction.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.