TY - JOUR AU - Galeazzi, Massimiliano PY - 2011 DA - 2011// TI - Fundamental noise processes in TES devices T2 - IEEE Trans. Appl. Supercond. JO - IEEE Trans. Appl. Supercond. SP - 267 EP - 271 VL - 21 IS - 3 KW - TES KW - Johnson noise KW - phonon noise KW - excess noise KW - flux-flow noise KW - thermal fluctuation noise AB - Microcalorimeters and bolometers are noise-limited devices, therefore, a proper understanding of all noise sources is essential to predict and interpret their performance. In this paper, I review the fundamental noise processes contributing to Transition Edge Sensor (TES) microcalorimeters and bolometers and their effect on device performance. In particular, I will start with a simple, monolithic device model, moving to a more complex one involving discrete components, to finally move to today's more realistic, comprehensive model. In addition to the basic noise contribution (equilibrium Johnson noise and phonon noise), TES are significantly affected by extra noise, which is commonly referred to as excess noise. Different fundamental processes have been proposed and investigated to explain the origin of this excess noise, in particular near equilibrium non-linear Johnson noise, flux-flow noise, and internal thermal fluctuation noise. Experimental evidence shows that all three processes are real and contribute, at different levels, to the TES noise, although different processes become important at different regimes. It is therefore time to discard the term "excess noise" and consider these terms part of the "fundamental noise processes" instead. N1 - Recommended by Klapwijk ID - Galeazzi2011 ER -