5 may 2015 - LMGP Séminar : Grégoire COIFFARD - Development of kinetic inductance detectors for millimeter astronomy and related problems in material science and process technology

Grégoire Coiffard ; PhD student
LMGP & IRAM (Institut de RadioAstronomie Millimétrique)
Supervisor: Stéphane Pignard (LMGP) - Co-advisor: K-F. Schuster (IRAM)

 Abstract

We present the kinetic inductance detectors (KIDs) for the NIKA (New IRAM KIDs Array) camera installed in the 30-meter telescope of IRAM at Pico Veleta (Spain). Kinetic inductance detectors are planar detectors, easy to fabricate at a relatively low cost making them suitable for large millimeter detectors arrays.

These detectors consist of a thin aluminium film deposited onto a silicon substrate and photolithographed. To ameliorate the absorption of millimeter wave in our detectors, we proposed to partially etch the silicon substrate to decrease its dielectric constant. This creates an intermediate layer which minimizes mm-wave reflection. Another improvement is the use of larger array with a number of detectors up to 2000. This require the design of a new instrument, we will shortly present it.

Finally, we will present the development of titanium nitride (TiN) thin film at IRAM. Sub-stoichiometric TiN is known to have a high value of kinetic inductance making it promising for our application. Unfortunately, the deposition process of such a TiN is difficult to control and to reproduce. It is also challenging to have homogenous nitrogen content on a wafer and this parameter is critical to design kinetic inductance arrays. We present various characterization techniques to quantify the reproducibility and the homogeneity of our TiN thin films.