Niobium Nitride Thin Films for Very Low Temperature Resistive Thermometry

Abstract

We investigate thin film resistive thermometry based on metal-toinsulator-transition (niobium nitride) materials down to very low temperature. The variation of the NbN thermometer resistance have calibrated versus temperature and magnetic field. High sensitivity in tempertaure variation detection is demonstrated through efficient temperature coefficient of resistance. The nitrogen content of the niobium nitride thin films can be tuned to adjust the optimal working temperature range. In the present experiment, we show the versatility of the NbN thin film technology through applications in very different low temperature use-cases. We demonstrate that thin film resistive thermometry can be extended to temperatures below 30 mK with low electrical impedance.Keywords resistive thermometry · niobium nitride · thin film · nanoscale 1 Introduction For applications in cryogenics, it becomes more and more useful to cover large temperature ranges with a single thermometry. Most of the conventional ther-

Micrometer Sized Hexagonal Chromium Selenide Flakes for Cryogenic Temperature Sensors

“…The sensitivity of the presently reported Cr-Se sensor is compared with sensitivities of other state-of-the-art temperature sensors found in literature (see Table 2). The Cr-Se sensor has a higher sensitivity than other materials such as RuO 2 , CrN, ZrN, Ge-GaAs, NbN, and NiCr [30][31][32][33][34][35] and comparable sensitivity with the best performing materials, such as InSb and FIB C-Pt. Although the last two sensors present relatively better sensitivities below 1 K, the newly reported sensor shows better sensitivities in the more common experimentally achievable temperature range from 1 K to 10 K. In addition, in contrast to the Czochralsky method [36] used to obtain the InSb material or the FIB [37] utilized for the C-Pt material, the PVT method employed for Cr-Se offers a simpler way to produce cryogenic thermometers.…”

Measuring the Optical Absorption of Single Nanowires

“…With a temperature sensitivity of about 100 mK, and a beam conduction of the order of 50 nW/K, this leads to a minimum measurable absorbed power of about 5 nW, as also demonstrated by accurately measuring an absorbed power of 12 nW in GaP NWs with a diameter of 75 nm. This resolution is limited by the noise in the preamp, which is expected to be true even at very low temperatures [30]. Note that this sensitivity is also a factor-2 improvement with respect to previous work [23] thanks to the simplified geometry where only one platform is used.…”

“…Furthermore, the temperature range can be extended by using an appropriate choice of metal. The method currently uses platinum resistive thermometers, which function most accurately at temperatures above 50 K, the temperature range can be extended easily by using different materials for the thermometers such as NbN for temperatures down to mK [30].…”

“…As a proof of principle, we show measurements performed at 70 K and at room temperature (due to slight heating by the laser the actual temperature at the laser spot is estimated to be at most 70 K above the measurement temperature at room temperature, and at most 20 K for the 70-K measurement). By replacing the Pt in the resistive thermometers with, e.g., NbN, measurements can in principle be done even at a few mK [30]. A similar approach has previously been used to measure the absorption of carbon nanotube bundles [23], but in this work we simplify the geometry (which enhances sensitivity as well as simplifies fabrication), apply it to semiconductor nanowires, and demonstrate the versatility by extending the wavelength range.…”

Electron beam lithography on non-planar, suspended, 3D AFM cantilever for nanoscale thermal probing

“…Next, the targeted application of our fabrication process is to integrate a niobium nitride resistive thermometer close to the apex of the AFM tip for scanning thermal measurements. As a temperature sensitive material, NbN thin films have been widely used for high-resolution temperature and thermal measurements over a broad temperature range from sub-Kelvin temperature in a dilution refrigerator to room temperature especially 9 for suspended systems [5,[46][47][48][49][50]. Combined with its low electrical thermal conductivity and a high resistance variation with temperature at 300 K, NbN is a very good candidate for room temperature as well as low temperature applications [46,50].…”