RTS Noise Detection and Voltage Effect on RTS in HgCdTe Focal-Plane Arrays
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https://doi.org/10.1007/s11664-020-08271-y Ó 2020 The Minerals, Metals & Materials Society
TOPICAL COLLECTION: U.S. WORKSHOP ON PHYSICS AND CHEMISTRY OF II-VI MATERIALS 2019
RTS Noise Detection and Voltage Effect on RTS in HgCdTe Focal-Plane Arrays ´ NIN ,1,4 SOPHIE DERELLE,2 MARCEL CAES,2 MAXENCE GUE LAURENT RUBALDO,3 and ISABELLE RIBET-MOHAMED2 1.—ONERA, DOTA, Universite´ Paris-Saclay, 91123 Palaiseau, France. 2.—ONERA/DOTA – Chemin de la Vauve aux Granges, 91120 Palaiseau, France. 3.—LYNRED, Avenue de la Vauve CS20018, 91127 Palaiseau Cedex, France. 4.—e-mail: [email protected]
An automated random telegraph signal (RTS) detection and characterization method and a blinking noise and slow drift separation method adapted to focal-plane arrays have been developed and applied to study the evolution of the number of RTS pixels and the amplitude of the blinking signal as functions of the reverse bias voltage and temperature. The results show that the physical characteristics of the RTS follow Arrhenius laws and increase with bias. The origin of this increase in the amplitude as a function of the reverse bias is discussed. Key words: Random telegraph signal, 1/f noise, reverse bias, image quality, algorithm
INTRODUCTION Temporal noise is one of the main challenges in the quest for high operability and stable image quality over time in infrared (IR) focal-plane arrays (FPAs). This type of noise cannot be corrected by a classical nonuniformity correction, as the extra parasitic noise signal may vary in time. Among the sources of temporal noise, low-frequency or 1/fa noise, where f is the frequency and a is a coefficient lying between 1 and 2, is one of the main sources of noise limiting the trend towards higher operating temperatures for cooled infrared sensors. The random telegraph signal is one of these. It exhibits significant current variations with seemingly random occurrences in time. It can affect small-scale image quality when the jump amplitude exceeds the residual fixed pattern noise and the very long-term stability through its impact on gain/offset correction tables. Therefore, understanding the physics behind this phenomenon is critical to improve the temporal stability of imaging using cooled sensors.
(Received January 31, 2020; accepted June 10, 2020)
Also called ‘‘blinking pixels’’ in the frame of FPAs, RTS pixels exhibit a multistable signal, i.e., a fluctuation between multiple states. Figure 1 shows a bistable RTS signal recorded on our FPA. It presents two stable states, separated by a jump characterized by an amplitude A and with lifetimes of sup and sdown. The mean values of the lifetimes and are commonly used to characterize the blinking frequency. In the case of a bistable RTS, the relation between the blinking lifetimes and the blinking frequency is described by Eq. 1: fc ¼
1 1 þ : hsdown i sup
ð1Þ
RTS has been detected in many types of systems, such as nanowires,1 silicon transistors,2 and photodetectors,3 as well as IR FPAs such as type 2 superlattice (T2SL),4 InGaAs,5 and HgCdTe
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